Engine Controls - Trouble Shooting - No Codes - 3.4l Chevrolet Monte Carlo VI

INTRODUCTION

Before diagnosing symptoms or intermittent faults, follow proper workflow. Go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no Diagnostic Trouble Codes (DTCs) are present and a no start condition exists, proceed to NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. If no DTCs are present and a driveability condition exists, diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).

Use intermittent test procedures to locate driveability problems that do not occur when the vehicle is being tested. These test procedures should also be used if a soft (intermittent) trouble code was present but no problem was found during self-diagnostic testing.

Note. For specific testing procedures, go to SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. For specifications, go to appropriate ON-VEHICLE ADJUSTMENTS or appropriate SERVICE & ADJUSTMENT SPECIFICATIONS article.

PRELIMINARY INSPECTION

Note. Manufacturer does not provide testing procedures for many individual systems and components. For system testing not listed, perform related DTC testing procedure. See appropriate SELF-DIAGNOSTICS article.

Several of the symptom procedures call for a careful visual and physical inspection. This can lead to correcting a problem without further tests and can save valuable time. This inspection should include the following areas

1. Verify on-vehicle diagnostics are working by performing diagnostic system check - engine controls. Go to «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Search for Technical Service Bulletins (TSBs).
3. Ensure PCM grounds are clean, tight, and properly located.
4. Check vacuum hoses for splits, kinks, leaks, restrictions and proper connections. Ensure vacuum hoses are correctly routed as shown on vehicle emission control information label.
5. Remove the air filter element and check for dirt and for restrictions.
6. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking, especially between the Mass Airflow (MAF) sensor and the throttle body.
7. Check for air leaks at all intake manifold sealing surfaces.
8. Check ignition wires for cracking, hardness, proper routing and carbon tracking.
9. Check wiring for proper connections and routing, pinches, burns, cuts or other damage.
10. Ensure PCM and MIL are functioning properly.
11. Ensure there are no DTCs stored, or only intermittent DTCs are present.
12. Ensure fuel control system is operating properly. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
13. Perform a careful visual inspection of all systems.

After all checks have been performed, verify customer complaint and locate correct symptom. Check items indicated under that symptom. These procedures will normally recommend testing of a specific system or component, such as EGR, ignition, TCC, etc. Go to SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article for appropriate test procedures.

Note. If PCM displays data but engine fails to start, go to NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

SYMPTOMS

Note. Manufacturer does not provide testing procedures for many individual systems and components. For symptom testing not listed, perform related DTC testing procedure. See SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Before proceeding with any symptom diagnosis, perform all steps under PRELIMINARY INSPECTION .

SYMPTOM DIAGNOSIS - ENGINE CONTROLS

Note. For exhaust system symptoms, go to DIAGNOSTIC STARTING POINT - ENGINE EXHAUST .

Symptom checks should not be used unless symptom occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in appropriate BASIC DIAGNOSTIC PROCEDURES and SELF-DIAGNOSTICS articles were performed before diagnosing a symptom. Symptoms available for diagnosis include

Symptoms available for diagnosis include

1. «BACKFIRES»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
2. «CUTS OUT, MISSES»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
3. «DETONATION/SPARK KNOCK»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
4. «DIESELING/RUN-ON»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
5. ENGINE CRANKS BUT DOES NOT RUN. See «NO-START DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__no-start-diagnosis) in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
6. «HESITATION, SAG OR STUMBLE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
7. «LACK OF POWER, SLUGGISH OR SPONGY»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
8. «POOR FUEL ECONOMY»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
9. «POOR FUEL FILL QUALITY»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
10. «ROUGH, UNSTABLE OR INCORRECT IDLE & STALLING»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)
11. «VEHICLE SURGES OR CHUGGLES»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l)

DIAGNOSTIC STARTING POINT - ENGINE EXHAUST

Begin the system diagnosis by reviewing the system description under EXHAUST SYSTEM in THEORY & OPERATION - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Reviewing the information will help determine the correct symptom diagnostic procedure when a malfunction exists. It will also help you determine if the condition described by the customer is normal operation. Perform SYMPTOM DIAGNOSIS - ENGINE EXHAUST to identify the correct procedure for diagnosing the system.

Visual/Physical Inspection

1. Check for aftermarket or non-OEM devices such as, but not including; tailpipe extensions, headers, and exhaust cutouts. This could affect the operation and proper performance of the exhaust system. This could affect the operation and proper performance of the exhaust system.
2. Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, engine temperature, engine load, and frequency of concern.
3. Check the easily accessible or visible system components for obvious damage or conditions which could cause any symptom.

Intermittent

Check the vehicle under the same conditions that the customer reported to verify the system is operating as designed.

Go to the symptom diagnostic procedure from the following list to diagnose the symptom

1. Exhaust hissing or exhaust popping noise. Go to «EXHAUST LEAKAGE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__exhaust-leakage) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Exhaust rattle, loud exhaust or exhaust buzz, groan, hum noises. Go to «EXHAUST NOISE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__exhaust-noise) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Loss of power, poor acceleration or poor fuel economy. Go to «RESTRICTED EXHAUST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Symptom Definition

Fuel ignites in intake manifold or in exhaust system, making a loud popping noise.

1. Go to «PRELIMINARY INSPECTION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__preliminary-inspection) before continuing.

Fuel System

1. Check for incorrect fuel pressure. Go to «FUEL PRESSURE TEST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__fuel-pressure-test) under FUEL SYSTEMS in BASIC DIAGNOSTICS PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check the fuel injectors. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for a contaminated fuel condition. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary.

Sensor/System

Inspect for the following intermittent ignition system conditions

1. Monitor the 24X crank sensor and the CMP sensor signal present parameters on the scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Check all CKP sensor "A" and CMP sensor circuits for intermittents.
2. Monitor the 3X parameter on the scan tool. If the 3X is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted, they may not set a Diagnostic Trouble Code (DTC) immediately, but are capable of causing driveability complaints.
3. Check the CKP sensor "B" for an internal short.

Inspect the Mass Airflow (MAF) sensor conditions. Ensure that the MAF sensor honeycomb is not damaged.

Ignition System

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the previous steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

Engine Mechanical

1. Check engine mechanical for the following conditions: Compression. See «COMPRESSION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__compression) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Sticking or leaking valves. Worn camshaft lobes. Valve timing. Worn rocker arms. Broken valve springs. Excessive oil in combustion chamber or leaking valve seals. For more information, go to appropriate article in ENGINES. Check for incorrect basic engine parts. Check the camshaft, cylinder heads, pistons, etc. in appropriate article in ENGINES. Go to appropriate article in ENGINES for diagnosis procedures.

Additional Inspections

1. Inspect intake and exhaust manifolds for casting flash.
2. Check the Torque Converter Clutch (TCC) operation.
3. Check the exhaust system for damaged or collapsed pipes. Check mufflers for heat distress or possible internal failure. Check the catalytic converter for plugged condition. Go to «EXHAUST SYSTEM»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases.

1. Check the fuel system circuits for proper operation. Go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (ALERO & GRAND AM)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-alero) or «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check for low fuel pressure. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for faulty fuel injectors. Go to «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) , «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) or «FUEL INJECTOR COIL TEST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-coil-test) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Inspect for fuel contamination. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Inspect any items which may cause an engine to run rich, long term fuel trim is significantly in the negative range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
6. Inspect any items which may cause an engine to run lean, long term fuel trim is significantly in the positive range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Go to PRELIMINARY INSPECTION before continuing.

1. Inspect for conditions which may cause an incorrect idle speed: Throttle body tampering, excessive deposits, or damage. Restricted air intake system. Large vacuum leak. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the Mass Airflow (MAF) sensor and the throttle body.
2. Inspect the Throttle Position (TP) sensor and related circuit wiring. Refer to «DTC P0123: THROTTLE POSITION SENSOR CIRCUIT - HIGH VOLTAGE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0123-throttle-position-sensor-circuit) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Monitor the 24X crank sensor and the CMP sensor signal parameters on the scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Check all CKP sensor "A" and CMP sensor circuits for intermittents.
4. Monitor the 3X crank sensor parameter on the scan tool. If the 3X crank sensor parameter is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted, they may not set a Diagnostic Trouble Code (DTC) immediately, but are capable of causing driveability complaints.
5. Check the CKP sensor "B" for an internal short. Go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
6. Check the Exhaust Gas Recirculation (EGR) system for proper operation.
7. Check the Positive Crankcase Ventilation (PCV) valve for proper operation.
8. Inspect the Transaxle Range Switch input with the vehicle in drive and the gear selector in drive or overdrive.
9. Inspect the following for damage: Bent balancer interrupter rings. Damaged Crankshaft Position (CKP) sensor.

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the previous steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

1. Inspect engine mechanical for the following conditions: Compression. See «COMPRESSION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__compression) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Sticking or leaking valves. Worn camshaft lobes. Valve timing. Bent push rods. Worn rocker arms. Broken valve springs. Excessive oil in combustion chamber or leaking valve seals. Low cylinder compression.
2. For incorrect basic engine parts. Check the camshaft, cylinder heads, pistons, etc. in appropriate article in ENGINES.
3. Go to appropriate article in ENGINES for diagnosis procedures.

1. Inspect the exhaust system for possible restrictions: Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. For possible plugged catalytic converter. Go to «RESTRICTED EXHAUST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. An engine miss condition can be caused by Electromagnetic Interference (EMI) on the reference circuit. EMI can usually be detected by monitoring engine RPM using a scan tool. A sudden increase in RPM with little change in actual engine RPM change, indicates EMI is present. If a problem exists, inspect routing of secondary ignition wires, high voltage components, near the ignition control circuits.

A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks which change with amount of acceleration.

Preliminary Inspections

Go to PRELIMINARY INSPECTION before continuing.

1. Check the fuel system circuits for proper operation. Go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check for a restricted fuel filter. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for faulty fuel injectors. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Check for a contaminated fuel condition. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Inspect any items which may cause an engine to run rich, long term fuel trim is significantly in the negative range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
6. Inspect any items which may cause an engine to run lean, long term fuel trim is significantly in the positive range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Inspect the spark plugs for proper heat range and reach. Go to SPARK PLUGS under IGNITION SYSTEMS in SERVICE & ADJUSTMENT SPECIFICATIONS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the above steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

Engine Cooling System

Check for obvious overheating conditions

1. Low engine coolant.
2. A faulty thermostat.
3. A restricted air flow to the radiator or restricted coolant flow through the radiator.
4. An inoperative electric cooling fan.
5. Proper tension on the drive belts.
6. Correct coolant solution should be a 50/50 mix.

Inspect for obvious overheating problems

1. Low engine coolant.
2. Restricted air flow to radiator, or restricted water flow through the radiator.
3. Inoperative electric cooling fan circuits.
4. Correct coolant solution should be a 50/50 mix.

Check for the following engine mechanical conditions

1. Excessive oil in combustion chamber or leaking valve seals.
2. Low cylinder compression. See «COMPRESSION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__compression) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for incorrect basic engine parts. Check the camshaft, cylinder heads, pistons, etc. See appropriate article in ENGINES.

1. Check the CKP sensor "B" for an internal short.
2. Check for proper Exhaust Gas Recirculation (EGR) system operation. Go to «DTC P0401: EGR SYSTEM»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0401-egr-system) .
3. Inspect the Transaxle Range Switch input with the vehicle in drive and the gear selector in drive or overdrive.
4. Check the Torque Converter Clutch (TCC) operation. TCC applying too soon can cause the engine to spark knock.
5. If the scan tool readings are normal and there are no engine mechanical faults, fill the fuel tank with a known quality gasoline that has a minimum octane reading of 87 and re-evaluate vehicle performance.

Engine continues to run after ignition is turned off but runs very rough. If engine runs smoothly, check ignition switch and adjustment.

1. Go to «PRELIMINARY INSPECTION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__preliminary-inspection) before continuing.
2. Refer to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) before starting.

1. Check the fuel system circuits for proper operation. Go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (ALERO & GRAND AM)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-alero) or «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO)»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check for low fuel pressure. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for faulty fuel injectors. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Inspect for fuel in the pressure regulator vacuum hose.
5. Ensure that each injector harness is connected to the correct injector/cylinder.

Check for short between battery positive voltage and any of the ignition feed circuits.

Engine cranks OK, but does not start for a long time. Does eventually run, or may start but immediately stalls.

Go to PRELIMINARY INSPECTION before continuing.

Refer to INTERMITTENTS before starting.

1. Check for an Engine Coolant Temperature (ECT) sensor that has shifted in value. Connect a scan tool and compare ECT with Intake Air Temperature (IAT) on a cold engine. The ECT and IAT should be within 5°F of each other. Check the resistance of the ECT sensor if the temperature is out of range with the IAT sensor. Go to «TEMPERATURE VS. RESISTANCE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l) table. If the ECT sensor resistance is not within the specification, go to «DTC P0117: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT - LOW VOLTAGE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0117-engine-coolant-temperature-sensor) or «DTC P0113: INTAKE AIR TEMPERATURE SENSOR CIRCUIT - HIGH VOLTAGE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0113-intake-air-temperature-sensor) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Monitor the 24X crank sensor and CMP sensor signal present parameters on a scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Check all CKP sensor A and CMP sensor circuits for intermittents.
3. Monitor the 3X crank sensor parameter on the scan tool. If the 3X crank sensor parameter is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted, they may not set a DTC immediately, but are capable of causing driveability complaints.
4. Inspect the Mass Airflow (MAF) sensor for proper installation and conditions. A MAF sensor with a damaged honeycomb may cause a hard start. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking, especially between the MAF sensor and the throttle body.
5. Using a scan tool, test the Idle Air Control (IAC) operation. Command the engine RPM to 1500 RPM and back to the starting RPM. If the engine RPM does not change when commanded refer to «DTC P0506: IDLE SPEED LOW»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0506-idle-speed-low) and «DTC P0507: IDLE SPEED HIGH»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0507-idle-speed-high) to diagnose the IAC system.
6. Inspect the Exhaust Gas Recirculation (EGR) system for proper sealing/connections and operation.

(1) TEMPERATURE VS. RESISTANCE

1. Verify there is adequate fuel.
2. Check the fuel system circuits for proper operation. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for low fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Check for faulty fuel injectors. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Check for a contaminated fuel condition. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the above steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

1. Excessive oil in combustion chamber or leaking valve seals.
2. Low cylinder compression. See «COMPRESSION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__compression) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Improper valve timing.
4. Combustion chambers for excessive carbon buildup. Clean the chambers using top engine cleaner. Follow manufacturers instructions on the can.
5. Check for incorrect basic engine parts. Check the camshaft, cylinder heads, pistons, etc. Go to appropriate article in ENGINES.

Momentary lack of response when accelerator is pushed down. Condition occurs at all vehicle speeds or usually occurs when taking off from a stop. If severe enough, may cause engine to stall.

Go to PRELIMINARY INSPECTION before continuing.

Refer to INTERMITTENTS before starting.

Note. Contamination of the oxygen sensor can result from the use of an inappropriate RTV sealant (not oxygen sensor safe) or excessive engine coolant or oil consumption. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream to check for contamination. If contaminated, the portion of the sensor exposed to the exhaust stream will have a White powdery coating. Silicone contamination causes a high but false HO2S signal voltage (rich exhaust indication). The Powertrain Control Module (PCM) will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Eliminate the source of contamination before replacing the oxygen sensor.

1. Monitor the Heated Oxygen Sensors (HO2S). The HO2Ss should respond quickly to different throttle positions. If not, inspect the HO2S for silicone or other contaminants from fuel or use of improper RTV sealant. The sensors may have a White powdery coating. Silicone contamination causes a high but false HO2S signal voltage, rich exhaust indication. The PCM will reduce the amount of fuel delivered to the engine, causing a severe driveability problem.
2. Monitor the 24X crank sensor and the CMP sensor signal present parameters on the scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Check all CKP A and CMP sensor circuits for intermittents. Go to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) .
3. Monitor the 3X crank sensor parameter on the scan tool. If the 3X crank sensor parameter is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the 3X low reference circuit for intermittents. Go to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) . If these circuits become open or shorted they may not set a Diagnostic Trouble Code (DTC) immediately, but are capable of causing driveability complaints.
4. Check the CKP sensor "B" for an internal short. Go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Inspect the Throttle Position (TP) sensor and related wiring.
6. Inspect the Mass Airflow (MAF) sensor and related wiring. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the MAF sensor and the throttle body.
7. Check the Exhaust Gas Recirculation (EGR) system for proper operation.

1. Check the fuel system circuits for proper operation. Go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check for low fuel pressure. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for faulty fuel injectors. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Check for a contaminated fuel condition. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Inspect any items which may cause an engine to run rich, long term fuel trim is significantly in the negative range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
6. Inspect any items which may cause an engine to run lean, long term fuel trim is significantly in the positive range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the above steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

Engine delivers less than expected power. Little or no increase in speed when the accelerator pedal is pushed down part way.

Go to PRELIMINARY INSPECTION before continuing.

Refer to INTERMITTENTS before starting.

1. Check the fuel system circuits for proper operation. Go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check for low fuel pressure. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for faulty fuel injectors. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Check for a contaminated fuel condition. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Inspect any items which may cause an engine to run rich, long term fuel trim is significantly in the negative range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
6. Inspect any items which may cause an engine to run lean, long term fuel trim is significantly in the positive range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

1. Check the CKP sensor "B" for an internal short. Go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Using a scan tool, monitor Knock Sensor (KS) system for excessive spark retard activity.
3. Use a scan tool to monitor the Knock Sensor (KS) system for excessive spark retard activity.
4. If knock retard is above 10-12 degrees , disconnect the KS harness connector, and ground the sensor harness connector. Monitor knock retard on the scan tool. There should be no knock retard present. If knock retard is still present, replace the PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See «POWERTRAIN CONTROL MODULE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) under PROGRAMMING in SELF-DIAGNOSTICS 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Inspect the Exhaust Gas Recirculation (EGR) system for proper operation.
6. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the Mass Airflow (MAF) sensor and the throttle body.

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the above steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

1. Check for excessive oil in the combustion chambers and leaking valve seals. See appropriate article in ENGINES.
2. Check for low cylinder compression. See «COMPRESSION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__compression) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for incorrect basic engine parts. Check the camshaft, cylinder heads, pistons, etc. Go to appropriate article in ENGINES.

1. Check the exhaust system for the following possible restrictions: The exhaust system for damaged or collapsed pipes. The mufflers for heat distress or internal failure. Go to «RESTRICTED EXHAUST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check the Transmission Torque Converter Clutch (TCC) operation. The TCC applying too soon can cause the engine to spark knock. Go to appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, fuel economy is noticeably lower than the economy was on this vehicle at one time, as previously shown by an actual road test.

Go to PRELIMINARY INSPECTION before continuing.

Refer to INTERMITTENTS before starting.

Discuss driving habits with the owner. Is the A/C or the Defroster mode ON full time? Are the tires at the correct pressure? Are the wheels and tires the correct size? Are there excessively heavy loads being carried? Is the acceleration rate too much, too often?

1. Check the fuel system circuits for proper operation. Go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check for low fuel pressure. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for faulty fuel injectors. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Check for a contaminated fuel condition. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Check that each fuel injector harness is connected to the correct injector and cylinder. Relocate the injector harnesses as necessary.
6. Check for fuel in the pressure regulator vacuum hose. If there is fuel in the hose replace the regulator.

1. Observe the 24X crank sensor and the CMP sensor signal present parameters on the scan tool. If both are not responding, inspect the sensor feed circuit. Both sensors use a common feed circuit.
2. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking, especially between the Mass Airflow (MAF) sensor and the throttle body.
3. Inspect for proper operation of the speedometer. Go to appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the above steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

1. Ensure engine coolant level is full.
2. Check the engine thermostat for proper operation and for correct heat range. Go to «TEMPERATURE VS. RESISTANCE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l) table.

1. Check engine mechanical for the following conditions: Check compression. See «COMPRESSION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__compression) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Sticking or leaking valves. Worn camshaft lobes. Valve timing. Worn rocker arms. Broken valve springs. Excessive oil in combustion chamber or leaking valve seals. Go to appropriate article in ENGINES.
2. Check for incorrect basic engine parts. Check the camshaft, cylinder heads, pistons, etc. Go to appropriate article in ENGINES.

1. Check the transmission Torque Converter Clutch (TCC) operation. The scan tool should indicate a RPM drop, when the system commands the TCC ON. Go to appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
2. Check the exhaust system for a possible restriction. Check for damaged or collapsed pipes, mufflers for heat distress or possible internal failure and catalytic converters for a plugged condition. Go to «RESTRICTED EXHAUST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

During the fueling process a continual, occasional or no fuel nozzle shut-off condition has occurred.

Preliminary

Go to PRELIMINARY INSPECTION before continuing.

Occasional Shut-Off Of Fuel Dispensing Nozzle

1. Fill limiter vent valve stuck closed.
2. Evaporative Emission (EVAP) canister restricted.
3. EVAP vent valve stuck closed.
4. High Reid vapor pressure or high fuel temperature.
5. Fuel filler hose is pinched or kinked.

No Nozzle Shut-Off/Overfill

1. Pressure relief valve is stuck open or leaking.
2. Fill limiter vent valve stuck open or leaking.

Continual Shut-Off Of Fuel Dispensing Nozzle

1. Fill limiter vent valve stuck closed.
2. EVAP canister restricted.
3. EVAP vent valve stuck closed.
4. Restricted or pinched vapor lines.
5. High Reid vapor pressure or high fuel temperature.
6. Blocked fuel filler hose/pipe or fuel fill check valve.

Engine runs unevenly at idle. If severe, the engine or vehicle may shake. Engine idle speed may vary in RPM. Either condition may be severe enough to stall the engine.

1. Go to «PRELIMINARY INSPECTION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__preliminary-inspection) before continuing.
2. Discuss driving habits with the owner.

1. Check the fuel system circuits for proper operation. Go to «FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-pump-electrical-circuit-diagnosis-impala) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check for low fuel pressure. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Check for faulty fuel injectors. Go to «FUEL INJECTOR CIRCUIT DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-circuit-diagnosis) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
4. Check for a contaminated fuel condition. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Inspect any items which may cause an engine to run rich, long term fuel trim is significantly in the negative range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
6. Inspect any items which may cause an engine to run lean, long term fuel trim is significantly in the positive range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

1. Check for conditions which cause an incorrect idle speed: Throttle body tampering, excessive deposits, or damage. Restricted air intake system. Large vacuum leak.
2. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the Mass Airflow (MAF) sensor and the throttle body.
3. Inspect crankcase ventilation valve for proper operation.
4. Check the Throttle Position (TP) sensor and related wiring. Go to «DTC P0123: THROTTLE POSITION SENSOR CIRCUIT - LOW VOLTAGE»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l__dtc-p0123-throttle-position-sensor-circuit) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Monitor the 24X crank sensor and the CMP sensor present parameters on the scan tool. If both are not responding, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Check all CKP sensor "A" and CMP sensor circuits for intermittents. See «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) .
6. Monitor the 3X parameter on the scan tool. If the 3X is not responding, inspect the CKP sensor "B" and circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted may not set a DTC immediately, but are capable of causing driveability complaints
7. Check the Exhaust Gas Recirculation (EGR) system for proper operation.
8. Inspect the transaxle range switch input with the vehicle in drive and the gear selector in drive or overdrive. See appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the above steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

1. Inspect Engine Mechanical for the following conditions: Check compression. See «COMPRESSION»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-34l__compression) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article. Sticking or leaking valves. Worn camshaft lobes. Valve timing. Worn rocker arms. Broken valve springs. Excessive oil in combustion chamber or leaking valve seals.
2. Check for incorrect basic engine parts. Check the camshaft, cylinder heads, pistons, etc. Go to appropriate article in ENGINES.

1. Check the exhaust system for possible restrictions. Go to «RESTRICTED EXHAUST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Inspect the exhaust system for damaged or collapsed pipes.
3. Inspect the mufflers for heat distress or possible internal failure.
4. Check for possible catalytic converter restrictions by testing the exhaust system back pressure.
5. An engine miss condition can be caused by Electromagnetic Interference (EMI) on the reference circuit. EMI can usually be detected by monitoring engine RPM with a scan tool. A sudden increase in RPM with little change in actual engine RPM change, indicates EMI is present. If a condition exists, inspect the routing of secondary ignition wires, high voltage components (e.g. near ignition control circuits).
6. Inspect for intake and exhaust manifold passages for casting flash.

Engine power variation under steady throttle or cruise. Feels like the vehicle speeds up and slows down with no change in the accelerator pedal position.

Go to PRELIMINARY INSPECTION before continuing.

Refer to INTERMITTENTS before starting.

Verify the driver understands transmission Torque Converter Clutch (TCC), and A/C compressor operation as explained in the owners manual. Inform customer how TCC and the A/C clutch operates.

1. Monitor the Heated Oxygen Sensors (HO2S). The HO2Ss should respond quickly to different throttle positions. If not, inspect the HO2S for silicon or other contaminants from fuel or use of improper RTV sealant. Remove the HO2S and visually inspect the portion of the sensor exposed to the exhaust stream to check for contamination. The sensors may have a White powdery coating. Silicone contamination causes a high but false HO2S signal voltage which is a rich exhaust indication. The Powertrain Control Module (PCM) will reduce the amount of fuel delivered to the engine, causing a severe driveability problem.
2. Inspect the Mass Airflow (MAF) sensor and related wiring.
3. Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the MAF sensor and the throttle body.
4. Monitor the 24X crank sensor and the CMP sensor signal present parameters on the scan tool. If both sensors are not responding, test each sensor feed circuit. Each sensor uses a separate supply circuit but are internally connected to power. Check all CKP sensor A and CMP sensor circuits for intermittents. Go to «INTERMITTENTS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__intermittents) .
5. Monitor the 3X crank sensor parameter on the scan tool. If the 3X crank sensor parameter is not responding, inspect the CKP sensor "B" and related circuits for intermittents. Inspect the Ignition Control (IC) circuit, IC timing control circuit, low resolution engine speed signal circuit and the low reference circuit for intermittents. If these circuits become open, or shorted may not set a DTC immediately, but are capable of causing driveability complaints.
6. Check the CKP sensor "B" for an internal short. Go to «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
7. Check the Exhaust Gas Recirculation (EGR) system for proper operation.

1. Check fuel pressure. Go to «FUEL SYSTEM DIAGNOSIS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l__fuel-system-diagnosis) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
2. Check for a contaminated fuel condition. Go to «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
3. Ensure each fuel injector harness is connected to the correct fuel injector/cylinder.
4. Inspect any items which may cause an engine to run rich, long term fuel trim is significantly in the negative range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.
5. Inspect any items which may cause an engine to run lean, long term fuel trim is significantly in the positive range. Go to «DIAGNOSTIC AIDS»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-self-diagnostics-34l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Inspect for proper ignition voltage output using the following steps

1. Attach the Spark Tester (J 26792) to engine ground.
2. Connect the spark plug end of the spark plug wire to the spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
3. Connect the spark plug end of the companion spark plug wire to ground. The companion spark plug wire is the wire attached to the corresponding coil tower.
4. Crank the engine while observing the spark tester. A spark should be observed.
5. Repeat the above steps for each coil.

If spark is not present at the coils, inspect for the following conditions

1. Coils - Cracks, carbon tracking/arcing, or a resistance value outside 5-8 k/ohms.
2. Spark Plug Wires - Signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside 3000 ohms per foot.
3. Defective Ignition Module
4. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring

Remove spark plugs and inspect for the following conditions

1. Fouled plugs
2. Cracks
3. Wear
4. Improper gap
5. Burned or damaged electrodes
6. Improper heat range or reach

If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

1. Check the transmission Torque Converter Clutch (TCC) operation. A TCC applying too soon can cause the engine to spark knock. Go to appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS.
2. Check the A/C clutch for proper operation. Go to appropriate MANUAL A/C-HEATER SYSTEMS article in HVAC.
3. Check the exhaust system for possible restrictions. Go to «RESTRICTED EXHAUST»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-system-component-testing-34l) under EXHAUST SYSTEMS in SYSTEM & COMPONENT TESTS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

INTERMITTENTS

PROBLEM DIAGNOSIS

Intermittent fault testing requires duplicating circuit or component failure to identify problem. These procedures may lead to computer setting a fault code (on some systems) which may help in diagnosis.

If problem vehicle does not produce fault codes, monitor voltage or resistance values using a DVOM while attempting to reproduce conditions causing intermittent fault. A status change on DVOM indicates a fault has been located.

Use a DVOM to pinpoint faults. When monitoring voltage, ensure ignition switch is in ON position or engine is running. Ensure ignition switch is in OFF position or negative battery cable is disconnected when monitoring circuit resistance. Status changes on DVOM during test procedures indicate area of fault.

Note. The condition may or may not illuminate the Malfunction Indicator Light (MIL) or store a Diagnostic Trouble Code (DTC). The fault must be present to be diagnosed.

Perform the Diagnostic System Check - Engine Controls before starting. Go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Definition

The condition is not currently present but is indicated in DTC History or there is a customer complaint, but the symptom can not currently be duplicated, if the condition is not DTC related.

Harness/Connector

Many intermittent open or shorted circuits come and go with harness/connector movement caused by vibration, engine torque, bumps/rough pavement, etc. Check for this type of condition by performing the applicable procedure from the following list

1. Move related connectors and wiring while monitoring the appropriate scan tool data.
2. Move related connectors and wiring with the component commanded ON, and OFF, with the scan tool. Observe the component operation.
3. With the engine running, move related connectors and wiring while monitoring engine operation.

If harness or connector movement affects the data displayed, component/system operation, or engine operation, inspect and repair the harness/connections as necessary. Go to ELECTRICAL CONNECTIONS OR WIRING .

Electrical Connections Or Wiring

1. Poor electrical connections/terminal tension or wiring conditions cause most intermittents. Perform a careful inspection of the suspected circuit for the following: Inspect for poor mating of the connector halves, or terminals not fully seated in the connector body (backed-out). Inspect for improperly formed or damaged terminals. Check for poor terminal tension. Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body. Inspect for corrosion/water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation, with little visible evidence. Look for swollen and stiff sections of wire in the suspect circuits. Inspect for wires that are broken inside the insulation. Inspect the harness for pinched, cut or rubbed through wiring. Ensure wiring does not come in contact with hot exhaust components.

Control Module/Component Power & Grounds

Poor power or ground connections can cause widely varying symptoms.

1. Check all Powertrain Control Module (PCM) power circuits. Many vehicles have multiple circuits supplying power to the PCM. Other components in the system may have separate power circuits that may also need to be tested. Inspect connections at the module/component connectors, fuses, and any intermediate connections between the power source and the module/component. A test light or a DMM may indicate that voltage is present, but neither tests a circuit ability to carry sufficient current. Ensure that the circuit can carry the current necessary to operate the component.
2. Check all control module ground and system ground circuits. The PCM may have multiple ground circuits. Other components in the system may have separate grounds that may also need to be tested. Inspect grounds for clean and tight connections at the grounding point. Inspect the connections at the component and in splice packs, where applicable. Ensure that the circuit can carry the current necessary to operate the component.

Temperature Sensitivity

1. An intermittent condition may occur when a component/connection reaches normal operating temperature. The condition may occur only when the component/connection is cold, or only when the component/connection is hot.
2. Freeze Frame, Failure Records, Snapshot or Vehicle Data Recorder data may help with this type of intermittent condition, where applicable.
3. If the intermittent is related to heat, review the data for a relationship with the following: High ambient temperatures. Underhood/engine generated heat. Circuit generated heat due to a poor connection, or high electrical load. Higher than normal load conditions (towing, etc.).
4. If the intermittent is related to cold, review the data for the following: Low ambient temperatures. In extremely low temperatures, ice may form in a connection or component. Check for water intrusion. The condition only occurs on a cold start. The condition goes away when the vehicle warms up.
5. Information from the customer may help to determine if the trouble follows a pattern that is temperature related.

Electromagnetic Interference & Electrical Noise

Some electrical components/circuits are sensitive to Electromagnetic Interference (EMI) or other types of electrical noise. Inspect for the following conditions

1. A misrouted harness that is too close to high voltage/high current devices such as secondary ignition components, motors, generator, etc. These components may induce electrical noise on a circuit that could interfere with normal circuit operation.
2. Electrical system interference caused by a malfunctioning relay, Powertrain Control Module (PCM) driven solenoid or switch. These conditions can cause a sharp electrical surge. Normally, the condition occurs when the malfunctioning component is operating.
3. Improper installation of non-factory or aftermarket add on accessories such as lights, 2-way radios, amplifiers, electric motors, remote starters, alarm systems, cell phones, etc. These accessories may lead to an emission related OBD II failure while in use, but do not fail when the accessories are not in use. If a DTC is determined to be intermittent, and the tests in this section do not reveal a condition, go to «VEHICLE DATA RECORDER»(/chevrolet/monte-carlo/vi-1999-2007/remont/testing-diagnostics/#engine-controls-trouble-shooting-no-codes-34l__vehicle-data-recorder) later in this table.
4. Check for an open diode across the A/C compressor clutch and for other open diodes. Some relays may contain a clamping diode.
5. Check the generator for a bad rectifier bridge that may be allowing AC noise into the electrical system.

Incorrect PCM Programming

Note. DO NOT re-program the PCM with the SAME software/calibration files that are already present in the PCM. This is not an effective repair for any type of driveability condition.

1. There are only a few situations where reprogramming a PCM is appropriate: A new service PCM is installed. A PCM from another vehicle is installed. Revised software/calibration files have been released for this vehicle.

Verify that the PCM contains the correct software/calibration. If incorrect programming is found, reprogram the PCM with the most current software/calibration. Go to POWERTRAIN CONTROL MODULE under PROGRAMMING in SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO article.

Duplicating Failure Conditions

If none of the previous tests are successful, attempt to duplicate and/or capture the failure conditions.

Freeze Frame/Failure Records, where applicable, contains the conditions that were present when the DTC set.

1. Review and record Freeze Frame/Failure Records data.
2. Clear the DTCs using the scan tool.
3. Turn the key to OFF and wait 15 seconds.
4. Operate the vehicle under the same conditions that were noted in Freeze Frame/Failure Records data, as closely as possible. The vehicle must also be operating within the conditions for running the DTC. Refer to conditions for running the DTC in the supporting text of the DTC being diagnosed.
5. Monitor DTC Status for the DTC being tested. The scan tool indicates RAN, when the enabling conditions have been satisfied long enough for the DTC to run. The scan tool also indicates whether the DTC passed or failed.

An alternate method is to drive the vehicle with the DMM connected to a suspected circuit. An abnormal reading on the DMM when the condition occurs, may help you locate the condition.

Scan Tool Snapshot

The scan tool can be set up to take a Snapshot of the parameters available via serial data. The Snapshot function records live data over a period of time. The recorded data can be played back and analyzed. The scan tool can also graph parameters singly or in combinations of parameters for comparison. The Snapshot can be triggered manually at the time the symptom is noticed, or set up in advance to trigger when a DTC sets.

An abnormal value captured in the recorded data may point to a system or component that needs to be investigated further. Refer to the scan tool user instructions for more information on the Snapshot function.

Vehicle Data Recorder

The Vehicle Data Recorder (J 42598) is connected to the Data Link Connector (DLC) and sent with the customer. The vehicle data recorder captures data for later retrieval and analysis by the technician. Refer to the vehicle data recorder user instructions for more information.

ALERO

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

GRAND AM

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

IMPALA

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

MONTE CARLO

See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

See also:
• DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS
• NO-START DIAGNOSIS
• SYSTEM & COMPONENT TESTING - 3.4L ALERO, GRAND AM, IMPALA & MONTE CARLO
• FUEL SYSTEM DIAGNOSIS
• EXHAUST SYSTEM
• EXHAUST LEAKAGE
• EXHAUST NOISE
• FUEL PRESSURE TEST
• FUEL INJECTOR CIRCUIT DIAGNOSIS
• FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL
• FUEL INJECTOR BALANCE TEST WITH TECH 2
• COMPRESSION
• FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (ALERO & GRAND AM)
• FUEL PUMP ELECTRICAL CIRCUIT DIAGNOSIS (IMPALA & MONTE CARLO)
• FUEL INJECTOR COIL TEST
• DTC P0123: THROTTLE POSITION SENSOR CIRCUIT - HIGH VOLTAGE
• ELECTRONIC IGNITION SYSTEM DIAGNOSIS
• SPARK PLUGS
• DTC P0401: EGR SYSTEM
• DTC P0117: ENGINE COOLANT TEMPERATURE SENSOR CIRCUIT - LOW VOLTAGE
• DTC P0113: INTAKE AIR TEMPERATURE SENSOR CIRCUIT - HIGH VOLTAGE
• DTC P0506: IDLE SPEED LOW
• DTC P0507: IDLE SPEED HIGH
• COMPUTER RELEARN PROCEDURES - GENERAL MOTORS
• PRELIMINARY INSPECTION
• DIAGNOSTIC STARTING POINT - ENGINE EXHAUST
• BACKFIRES
• INTERMITTENTS
• ELECTRICAL CONNECTIONS OR WIRING
• VEHICLE DATA RECORDER