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Engine Controls Troubleshooting - No Codes - 3.8l Buick Park Avenue II рестайлинг

Testing & Diagnostics ~8466 words

INTRODUCTION

Before diagnosing symptoms or intermittent faults, perform DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Use this article to diagnose driveability problems when a current DTC is not present.

Symptom checks are intended to direct the technician to malfunctioning component(s) so that further diagnosis may be performed. A symptom should lead to further testing of specific components or systems, or verification of adjustment specifications.

Use intermittent test procedures to locate intermittent driveability problems that do not occur when the vehicle is being tested. These problems may cause a noticeable driveability problem or cause the Malfunction Indicator Light (MIL) to illuminate on some vehicles.

It is also possible that certain driveability concerns have been rectified by the manufacturer through reprogramming the PCM. Check with manufacturer for latest information on updated programs.

Note. For specific testing procedures, see SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. To verify specifications, see appropriate ON-VEHICLE ADJUSTMENTS article, or SERVICE & ADJUSTMENT SPECIFICATIONS article.

PRELIMINARY INSPECTION

CAUTIONTo prevent damage caused by the improper probing of connector terminals, use Connector Test Adapter Kit (J 35616-A) for any test that requires probing the PCM harness connectors, the electrical center fuse/relay cavities, component terminals or component harness connectors.
  1. Verify on-vehicle diagnostics are working by performing «DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Verify no DTCs are stored, scan tool data is within normal operating range. Verify customer complaint. Perform visual/physical check.
  2. Ensure PCM grounds are clean, tight, and properly located.
  3. 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.
  4. Check for air leaks at all intake manifold sealing surfaces.
  5. Check ignition wires for cracking, hardness, proper routing and carbon tracking.
  6. Check wiring for proper connections and routing, pinches, burns, cuts or other damage.
  7. Ensure PCM and MIL are functioning properly.
  8. Ensure there are no DTCs stored, or only intermittent DTCs are present.
  9. Ensure fuel control system is operating properly. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  10. Perform fuel system pressure test. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  11. 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. Not all items listed under each symptom apply to all models and systems. These procedures will normally recommend testing of a specific system or component, such as EGR, ignition, TCC, etc. See SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article for test procedures. If the condition cannot be duplicated, or is determined to be intermittent, see INTERMITTENTS .

Note. If PCM displays data but engine fails to start, see NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

SYMPTOMS

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

SYMPTOM DIAGNOSIS

Symptom checks should not be used unless symptom occurs while vehicle is being tested. To reduce diagnostic time, ensure steps in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL and SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL articles were performed before diagnosing a symptom. Symptoms available for diagnosis include

  1. «CUTS OUT, MISSES»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  2. «DETONATION/SPARK KNOCK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  3. «ENGINE BACKFIRES»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  4. «ENGINE DIESELING/RUN-ON»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  5. «HARD START»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  6. «HESITATION, SAG OR STUMBLE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  7. «LACK OF POWER, SLUGGISH OR SPONGY»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  8. «POOR FUEL ECONOMY»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  9. «POOR FUEL FILL QUALITY»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  10. «ROUGH, UNSTABLE OR INCORRECT IDLE & STALLING»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)
  11. «VEHICLE SURGES OR CHUGGLES»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l)

Symptom Definition

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

Preliminary

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs).

Fuel System

  1. Check system fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Check the fuel injectors. See «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) and «FUEL INJECTOR BALANCE TEST WITH TECH 2»(ref-157117-S18060335812003080500000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Check for contaminated fuel. See «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  4. Inspect items which can cause an engine to run rich (long term fuel trim significantly in the negative range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  5. Inspect items that can cause an engine to run lean (long term fuel trim significantly in the positive range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  6. Inspect for fuel in the fuel pressure regulator vacuum hose.

Sensor/System

  1. Inspect for conditions which cause an incorrect idle speed. Check for throttle body tampering, excessive deposits, or damage. Check for restricted air intake system. Check for large vacuum leaks.
  2. Check the Throttle Position (TP) sensor and related circuit wiring. See «DTC P0123: TP SENSOR CIRCUIT - HIGH VOLTAGE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__dtc-p0123-tp-sensor-circuit) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Check Exhaust Gas Recirculation (EGR) system for proper operation. See «EXHAUST GAS RECIRCULATION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-gas-recirculation) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  4. Check the Positive Crankcase Ventilation (PCV) valve for proper operation. See POSITIVE CRANKCASE VENTILATION under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  5. Check the transaxle range switch input with the vehicle in Drive and the gear selector in Drive or Overdrive.
  6. Check for bent harmonic balancer interrupter rings. See appropriate article in ENGINES. Check for damaged Crankshaft Position (CKP) sensor.

Ignition System

  1. Check for proper ignition voltage output using the following steps: Clip Spark Tester (J 26792) to engine ground. Connect one end of a spark plug wire to the spark tester. Connect the other end of the spark plug wire to the coil being tested. Connect another spark plug wire between the remaining tower of the coil being tested and ground. Crank the engine while observing the spark tester. A crisp Blue spark should be observed. Repeat procedure for each coil.
  2. If spark is not present at the coils, inspect for the following conditions: Coils - Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified coil resistance range of 5-8 k/ohms. Spark Plug Wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range of 3000 ohms per foot (9840 ohms per meter) or 600 ohms per foot (1968 ohms per meter) for Police models. Spraying the secondary ignition wires with a light mist of water may help locate an intermittent condition. Ignition components will arc to ground when a secondary component is faulty. Defective Module - See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.
  3. Remove spark plugs and inspect for fouling, cracks, wear, improper gap, burned or damaged electrodes and for improper heat range or reach.
  4. If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
  5. Check for the following intermittent ignition system conditions: Intermittent CKP 18X signal. Intermittent ignition feed circuit or sensor ground circuit to the crankshaft position sensor or the camshaft position sensor. Intermittent 3X reference signal. Intermittent camshaft position signal.

Engine Mechanical

  1. Check and inspect engine mechanical condition for the following: Check compression. See «COMPRESSION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__cylinder-compression-pressure) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, broken valve springs or excess oil in combustion chambers. See appropriate article in ENGINES.
  2. Inspect for incorrect basic engine parts, such as camshaft, cylinder heads, pistons, etc. See appropriate article in ENGINES.

Additional Checks

  1. Check exhaust system for possible restrictions. Inspect for the following: Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. For possible plugged 3-way catalytic converter. See «EXHAUST SYSTEM CHECK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-system-check) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL 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 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 routing of secondary ignition wires, high voltage components (near ignition control circuits).
  3. Inspect for intake and exhaust manifold passages for casting flash.
  4. Inspect for faulty motor mounts.

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

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs).

  1. Check for low fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Check for contaminated fuel. See «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Check fuel injectors. Perform injector balance test. See «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-special) or «FUEL INJECTOR BALANCE TEST WITH TECH 2»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-tech) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  4. Inspect items that can cause an engine to run lean (long term fuel trim significantly in the positive range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Inspect the spark plugs for proper heat range and reach.

Engine Cooling System

Inspect for obvious overheating conditions

  1. Low engine coolant. Fill as necessary.
  2. Restricted air flow to radiator, or restricted water flow through radiator.
  3. Inoperative electric cooling fan circuits. See appropriate ELECTRIC COOLING FANS article in ENGINE COOLING.
  4. Correct coolant solution.
  1. Check for excessive oil in combustion chamber. Check for leaking valve seals. See appropriate article in ENGINES.
  2. Check for low cylinder compression. See «COMPRESSION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__cylinder-compression-pressure) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Combustion chambers for excessive carbon buildup. Clean using top engine cleaner. Follow manufacturer's instructions on can.
  4. Inspect for incorrect basic engine parts, such as camshaft, cylinder heads, pistons, etc. See appropriate article in ENGINES.
  1. Check for proper Exhaust Gas Recirculation (EGR) system operation. See «DTC P0401: EGR SYSTEM INSUFFICIENT FLOW»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__dtc-p0401-egr-system-insufficient-flow) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Inspect the Transaxle Range Switch input with the vehicle in Drive and the gear selector in Drive or Overdrive.
  3. Check Torque Converter Clutch (TCC) operation. TCC applying too soon can cause the engine to spark knock. See appropriate DIAGNOSIS article in TRANSMISSIONS.
  4. If 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.

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

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs).

  1. Check for the following intermittent ignition system conditions: Intermittent CKP 18X signal. Intermittent ignition feed circuit or sensor ground circuit to the crankshaft position sensor or the camshaft position sensor. Intermittent 3X reference signal. Intermittent camshaft position signal.
  2. Inspect the Mass Air Flow (MAF) sensor conditions. Ensure that the MAF sensor honeycomb is not damaged.
  1. Check for low fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Check for contaminated fuel. See «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Ensure each injector harness is connected to the correct injector/cylinder.
  1. Check for proper ignition voltage output using the following steps: Clip Spark Tester (J 26792) to engine ground. Connect one end of a spark plug wire to the spark tester. Connect the other end of the spark plug wire to the coil being tested. Connect another spark plug wire between the remaining tower of the coil being tested and ground. Crank the engine while observing the spark tester. A crisp Blue spark should be observed. Repeat procedure for each coil.
  2. If spark is not present at the coils, inspect for the following conditions: Coils - Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified coil resistance range of 5-8 k/ohms. Spark Plug Wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range of 3000 ohms per foot (9840 ohms per meter) or 600 ohms per foot (1968 ohms per meter) for Police models. Spraying the secondary ignition wires with a light mist of water may help locate an intermittent condition. Ignition components will arc to ground when a secondary component is faulty. Defective Module - See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.
  3. Remove spark plugs and inspect for fouling, cracks, wear, improper gap, burned or damaged electrodes and for improper heat range or reach.
  4. If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
  1. Check and inspect engine mechanical for the following: Check compression. See «COMPRESSION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__cylinder-compression-pressure) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, broken valve springs or excess oil in combustion chambers. See appropriate article in ENGINES.
  2. Inspect for incorrect basic engine parts, such as camshaft, cylinder heads, pistons, etc. See appropriate article in ENGINES.
  1. Inspect Intake and exhaust manifolds for casting flash.
  2. Check Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in TRANSMISSIONS.
  3. Check exhaust system for possible restrictions. Inspect for the following: Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. For possible plugged 3-way catalytic converter. See «EXHAUST SYSTEM CHECK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-system-check) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Engine continues to run after key is turned OFF, but runs very rough. If engine runs smooth, inspect the ignition switch and adjustment.

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs).

  1. Check the fuel injectors. See «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) AND «FUEL INJECTOR BALANCE TEST WITH TECH 2»(ref-157117-S18060335812003080500000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

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

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

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs).

A variety of sensor or physical conditions may result in a hard start condition without setting a Diagnostic Trouble Code (DTC). To determine if any of these conditions exist, perform the following

  1. Compare scan tool data to a known good vehicle or refer to Scan Tool Data List.
  2. Check 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 3-way catalytic converter. See «EXHAUST SYSTEM CHECK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-system-check) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

A variety of sensor or physical conditions may result in a hard start condition without setting a Diagnostic Trouble Code (DTC). To determine if any of these conditions exist, perform the following

  1. Check for contaminated fuel. See «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

A variety of ignition system conditions may result in a hard start condition without setting a DTC. To determine if any of these conditions exist. See ELECTRONIC IGNITION SYSTEM DIAGNOSIS under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

A variety of engine mechanical conditions may result in a hard start condition without setting a DTC. To determine if any of these conditions exist. See COMPRESSION under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

If incorrect compression is detected, check for carbon build-up, cam timing, oil fouling, incorrect parts, bent pushrods, rocker arms, valve springs, cam lobes, intake/exhaust manifold flashing and faulty head gaskets.

Momentary lack of response as the accelerator is pushed down. Can occur at any vehicle speed. Usually more pronounced when first trying to make the vehicle move, as from a stop sign. May cause the engine to stall if severe enough.

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs).

Check the following items

  1. Check the Heated Oxygen Sensors (HO2S). A HO2S 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 Powertrain Control Module (PCM) will reduce the amount of fuel delivered to the engine, causing a severe driveability condition.
  2. Check the Throttle Position (TP) sensor and related wiring.
  3. Check the Mass Air Flow (MAF) sensor and related wiring.
  4. Check the Exhaust Gas Recirculation (EGR) system for proper operation. See «EXHAUST GAS RECIRCULATION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-gas-recirculation) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  1. Check the fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Check for contaminated fuel. See «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Inspect items which can cause an engine to run rich (long term fuel trim significantly in the negative range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  4. Inspect items that can cause an engine to run lean (long term fuel trim significantly in the positive range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  1. Check for proper ignition voltage output using the following steps: Clip Spark Tester (J 26792) to engine ground. Connect one end of a spark plug wire to the spark tester. Connect the other end of the spark plug wire to the coil being tested. Connect another spark plug wire between the remaining tower of the coil being tested and ground. Crank the engine while observing the spark tester. A crisp Blue spark should be observed. Repeat procedure for each coil.
  2. If spark is not present at the coils, inspect for the following conditions: Coils - Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified coil resistance range of 5-8 k/ohms. Spark plug wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range of 3000 ohms per foot (9840 ohms per meter) or 600 ohms per foot (1968 ohms per meter) for Police models. Spraying the secondary ignition wires with a light mist of water may help locate an intermittent condition. Ignition components will arc to ground when a secondary component is faulty. Defective Module - See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.
  3. Remove spark plugs and inspect for fouling, cracks, wear, improper gap, burned or damaged electrodes and for improper heat range or reach.
  4. 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.

Preliminary Checks

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs).

Fuel System Checks

  1. Check system fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Check the fuel injectors. See «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) , «FUEL INJECTOR BALANCE TEST WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-balance-test-with-special) AND «FUEL INJECTOR BALANCE TEST WITH TECH 2»(ref-157117-S18060335812003080500000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Check for contaminated fuel. See «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  4. Inspect items which can cause an engine to run rich (long term fuel trim significantly in the negative range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  5. Inspect items that can cause an engine to run lean (long term fuel trim significantly in the positive range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  1. Inspect for excessive spark retard activity using a scan tool. See «KNOCK SENSOR»(ref-158560-S33829340052003100700000) under INPUT DEVICES in THEORY & OPERATION - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article for Knock Sensor (KS) system description.
  2. Inspect the Exhaust Gas Recirculation (EGR) system for proper operation. See «EXHAUST GAS RECIRCULATION»(ref-158560-S06784180682003100700000) for EGR system description.
  3. Inspect for a restricted air intake system. See «AIR INDUCTION SYSTEMS»(ref-158560-S01852089662003100700000) in THEORY & OPERATION - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article for air intake system description.
  1. Check for proper ignition voltage output using the following steps: Clip Spark Tester (J 26792) to engine ground. Connect one end of a spark plug wire to the spark tester. Connect the other end of the spark plug wire to the coil being tested. Connect another spark plug wire between the remaining tower of the coil being tested and ground. Crank the engine while observing the spark tester. A crisp Blue spark should be observed. Repeat procedure for each coil.
  2. If spark is not present at the coils, inspect for the following conditions: Coils - Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified coil resistance range of 5-8 k/ohms. Spark Plug Wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range of 3000 ohms per foot (9840 ohms per meter) or 600 ohms per foot (1968 ohms per meter) for Police models. Spraying the secondary ignition wires with a light mist of water may help locate an intermittent condition. Ignition components will arc to ground when a secondary component is faulty. Defective Module - See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.
  3. Remove spark plugs and inspect for fouling, cracks, wear, improper gap, burned or damaged electrodes and for improper heat range or reach.
  4. If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
  1. Excess oil in combustion chamber. Inspect for leaking valve seals. Inspect for incorrect engine parts, such as the camshaft, cylinder heads, pistons etc. See appropriate article in ENGINES.
  2. Check for low cylinder compression. See «COMPRESSION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__cylinder-compression-pressure) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  1. Check exhaust system for possible restrictions. Inspect for the following: Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. For possible plugged 3-way catalytic converter. See «EXHAUST SYSTEM CHECK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-system-check) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Inspect for proper Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in TRANSMISSIONS.

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

  1. Perform preliminary inspection. See «PRELIMINARY INSPECTION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-troubleshooting-no-codes-38l__preliminary-inspection) . Check for Technical Service Bulletins (TSBs).
  2. Review the owner's driving habits. Is A/C ON full time (Defroster mode ON)? Are tires at correct pressure? Are tires and wheels the correct size? Are excessively heavy loads being carried? Is acceleration too much, too often?
  1. Check system fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Check the fuel injectors. See «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) and «FUEL INJECTOR BALANCE TEST WITH TECH 2»(ref-157117-S18060335812003080500000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Ensure each injector harness is connected to the correct injector/cylinder.
  4. Inspect for fuel in the pressure regulator vacuum hose.
  1. Inspect the air intake system and crankcase for air leaks.
  2. Check for proper calibration of the speedometer. Connect the Signal Generator and Instrument Panel Tester (J 33431-C) to the Vehicle Speed Sensor (VSS) electrical connector. Turn ignition switch to RUN position. With the tester ON, monitor the speedometer.
  1. Check for proper ignition voltage output using the following steps: Clip Spark Tester (J 26792) to engine ground. Connect one end of a spark plug wire to the spark tester. Connect the other end of the spark plug wire to the coil being tested. Connect another spark plug wire between the remaining tower of the coil being tested and ground. Crank the engine while observing the spark tester. A crisp Blue spark should be observed. Repeat procedure for each coil.
  2. If spark is not present at the coils, inspect for the following conditions: Coils - Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified coil resistance range of 5-8 k/ohms. Spark Plug Wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range of 3000 ohms per foot (9840 ohms per meter) or 600 ohms per foot (1968 ohms per meter) for Police models. Spraying the secondary ignition wires with a light mist of water may help locate an intermittent condition. Ignition components will arc to ground when a secondary component is faulty. Defective Module - See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.
  3. Remove spark plugs and inspect for fouling, cracks, wear, improper gap, burned or damaged electrodes and for improper heat range or reach.
  4. If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
  1. Check for low coolant level. Fill as necessary.
  2. Inspect and check for an incorrect or faulty engine thermostat.
  1. Check and inspect engine mechanical for the following: Check compression. See «COMPRESSION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__cylinder-compression-pressure) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, broken valve springs or excess oil in combustion chambers. See appropriate article in ENGINES.
  2. Inspect for incorrect basic engine parts, such as camshaft, cylinder heads, pistons, etc. See appropriate article in ENGINES.
  1. Inspect for proper Torque Converter Clutch (TCC) operation. See appropriate DIAGNOSIS article in TRANSMISSIONS.
  2. Check exhaust system for possible restrictions. Inspect for the following: Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. For possible plugged 3-way catalytic converter. See «EXHAUST SYSTEM CHECK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-system-check) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

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

Difficult To Fill

Check the following items

  1. Fill limiter vent valve stuck closed.
  2. EVAP canister restricted.
  3. EVAP vent valve stuck closed.
  4. Restricted vapor lines.
  5. High Reid vapor pressure or high fuel temperature.
  6. Fuel filler hose is pinched or kinked.
  7. Ignition switch in RUN position (EVAP vent valve closed).

Over Fill

Check the following items

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

Pre-Mature Shut-Off Of The Fuel Dispensing Nozzle

Check the following items

  1. Fill limiter vent valve stuck closed.
  2. EVAP canister restricted.
  3. EVAP vent valve stuck closed.
  4. Restricted vapor lines.
  5. High Reid vapor pressure or high fuel temperature.
  6. Ignition switch in RUN position (EVAP vent valve closed).

Fuel Spitback

Check the following items

  1. Restricted EVAP canister.
  2. High Reid vapor pressure or high fuel temperature.
  3. Ignition switch in RUN position (EVAP vent valve closed).

Liquid To EVAP Canister

Check the following items

  1. Fill limiter vent valve stuck open or leaking.
  2. Over filled fuel tank (cramming during fueling).

Liquid Leak To Ground

Check the following items

  1. The pressure relief valve in the fill limiter vent valve is stuck open or leaking.
  2. Fuel filler pipe loose or ruptured.
  3. Leaking fuel tank.

Fuel Odor

Check the following items

  1. The pressure relief valve in the fuel limiter vent valve is stuck open or leaking.
  2. The EVAP canister is saturated.
  3. Seepage from fuel lank.

Engine runs unevenly at idle. If severe enough, vehicle will shake. Idle may vary in RPM. Either problem may cause stalling. Engine idles at incorrect RPM.

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs).

  1. Check system fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Check the fuel injectors. See «FUEL INJECTOR COIL TEST»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__fuel-injector-coil-test) and «FUEL INJECTOR BALANCE TEST WITH TECH 2»(ref-157117-S18060335812003080500000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Check for contaminated fuel. See «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  4. Inspect items which can cause an engine to run rich (long term fuel trim significantly in the negative range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  5. Inspect items that can cause an engine to run lean (long term fuel trim significantly in the positive range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  6. Inspect for fuel in the fuel pressure regulator vacuum hose.
  7. Check for proper operation of EGR system.
  8. Ensure each injector harness is connected to the correct injector/cylinder.
  1. Inspect for conditions which cause an incorrect idle speed. Check for throttle body tampering, excessive deposits, or damage. Check for restricted air intake system. Check for large vacuum leaks.
  2. Check the Positive Crankcase Ventilation (PCV) valve for proper operation. See «POSITIVE CRANKCASE VENTILATION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Check the Throttle Position (TP) sensor and related circuit wiring. See «DTC P0123: TP SENSOR CIRCUIT - HIGH VOLTAGE»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l__dtc-p0123-tp-sensor-circuit) under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  4. Check the Exhaust Gas Recirculation (EGR) system for proper operation. See . «EXHAUST GAS RECIRCULATION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-gas-recirculation) under EMISSION SYSTEMS & SUB-SYSTEMS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  5. Check the transaxle range switch input with the vehicle in Drive and the gear selector in Drive or Overdrive.
  1. Check for proper ignition voltage output using the following steps: Clip Spark Tester (J 26792) to engine ground. Connect one end of a spark plug wire to the spark tester. Connect the other end of the spark plug wire to the coil being tested. Connect another spark plug wire between the remaining tower of the coil being tested and ground. Crank the engine while observing the spark tester. A crisp Blue spark should be observed. Repeat procedure for each coil.
  2. If spark is not present at the coils, inspect for the following conditions: Coils - Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified coil resistance range of 5-8 k/ohms. Spark Plug Wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range of 3000 ohms per foot (9840 ohms per meter) or 600 ohms per foot (1968 ohms per meter) for Police models. Spraying the secondary ignition wires with a light mist of water may help locate an intermittent condition. Ignition components will arc to ground when a secondary component is faulty. Defective Module - See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.
  3. Remove spark plugs and inspect for fouling, cracks, wear, improper gap, burned or damaged electrodes and for improper heat range or reach.
  4. If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
  1. Check and inspect engine mechanical condition for the following: Check compression. See «COMPRESSION»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__cylinder-compression-pressure) under MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Sticking or leaking valves, worn camshaft lobes, valve timing, bent push rods, worn rocker arms, broken valve springs or excess oil in combustion chambers. See appropriate article in ENGINES.
  2. Inspect for incorrect basic engine parts, such as camshaft, cylinder heads, pistons, etc. See appropriate article in ENGINES.
  1. Check exhaust system for possible restrictions. Inspect for the following: Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. For possible plugged 3-way catalytic converter. See «EXHAUST SYSTEM CHECK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-system-check) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Inspect for faulty motor mounts.
  3. 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 routing of secondary ignition wires, high voltage components (near ignition control circuits).
  4. 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.

Perform preliminary inspection. See PRELIMINARY INSPECTION . Check for Technical Service Bulletins (TSBs). Ensure the driver understands the transmission Torque Converter Clutch (TCC), and A/C compressor operation as explained in the owners manual. Inform the customer how the TCC and the A/C clutch operates.

  1. Check the Heated Oxygen Sensors (HO2S). A HO2S should respond quickly to different throttle positions. If not, inspect the suspect 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 Powertrain Control Module (PCM) will reduce the amount of fuel delivered to the engine, causing a severe driveability condition.
  2. Inspect the Mass Air Flow (MAF) sensor and related wiring.
  3. Check the Exhaust Gas Recirculation (EGR) system for proper operation.
  4. Check EGR system for proper operation.
  1. Check the fuel pressure. See «FUEL SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__fuel-system-diagnosis) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  2. Check for contaminated fuel. See «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITHOUT SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) or «ALCOHOL/CONTAMINANTS-IN-FUEL DIAGNOSIS WITH SPECIAL TOOL»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  3. Ensure each injector harness is connected to the correct injector/cylinder.
  4. Inspect items which can cause an engine to run rich (long term fuel trim significantly in the negative range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0172: FUEL TRIM SYSTEM RICH under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  5. Inspect items that can cause an engine to run lean (long term fuel trim significantly in the positive range). See «DIAGNOSTIC AIDS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-control-system-self-diagnostics-38l) for DTC P0171: FUEL TRIM SYSTEM LEAN under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
  1. Check for proper ignition voltage output using the following steps: Clip Spark Tester (J 26792) to engine ground. Connect one end of a spark plug wire to the spark tester. Connect the other end of the spark plug wire to the coil being tested. Connect another spark plug wire between the remaining tower of the coil being tested and ground. Crank the engine while observing the spark tester. A crisp Blue spark should be observed. Repeat procedure for each coil.
  2. If spark is not present at the coils, inspect for the following conditions: Coils - Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified coil resistance range of 5-8 k/ohms. Spark plug wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range of 3000 ohms per foot (9840 ohms per meter) or 600 ohms per foot (1968 ohms per meter) for Police models. Spraying the secondary ignition wires with a light mist of water may help locate an intermittent condition. Ignition components will arc to ground when a secondary component is faulty. Defective Module - See «ELECTRONIC IGNITION SYSTEM DIAGNOSIS»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-basic-diagnostic-procedures-38l__electronic-ignition-system-diagnosis) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.
  3. Remove spark plugs and inspect for fouling, cracks, wear, improper gap, burned or damaged electrodes and for improper heat range or reach.
  4. If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
  1. Check TCC operation. See appropriate DIAGNOSIS article in TRANSMISSIONS.
  2. Check exhaust system for possible restrictions. Inspect for the following: Inspect exhaust system for damaged or collapsed pipes. Inspect mufflers for heat distress or possible internal failure. For possible plugged 3-way catalytic converter. See «EXHAUST SYSTEM CHECK»(/buick/park-avenue/ii-2002-2005/remont/testing-diagnostics/#engine-controls-system-component-testing-38l__exhaust-system-check) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

INTERMITTENTS

CAUTIONWhen battery is disconnected, vehicle computer and memory systems may lose memory data. Driveability problems may exist until computer systems have completed a relearn cycle. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION before disconnecting battery.

Perform the Diagnostic System Check - Engine Controls before starting. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Definition

The condition is not currently present but may be 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 Or Connector Intermittents

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, check and repair the harness/connections as necessary. See 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: Check for poor mating of the connector halves, or terminals not fully seated in the connector body (backed-out). Check for improperly formed or damaged terminals. Check for poor terminal tension. Check for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body. Check 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. Check for wires that are broken inside the insulation. Check the harness for pinched, cut or rubbed through wiring. Ensure that the wiring does not come in contact with hot exhaust components.
  2. Repair the condition as necessary.

Control Module Power & Grounds & Component Power & Grounds

Poor power or ground connections can cause widely varying symptoms.

  1. Check all control module power circuits. Many vehicles have multiple circuits supplying power to the control module. Other components in the system may have separate power circuits that may also need to be tested. Check connections at the module or component connectors, fuses, and any intermediate connections between the power source and the module or component. A test light or a Digital Multimeter (DMM) may indicate that voltage is present, but neither tests the ability of a circuit to carry sufficient current. Ensure that the circuit can carry the current necessary to operate the component. See POWER DISTRIBUTION in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
  2. Check all control module ground and system ground circuits. The control module may have multiple ground circuits. Other components in the system may have separate grounds that may also need to be tested. Check grounds for clean and tight connections at the grounding point. Check the connections at the component and in splice packs, where applicable. Ensure that the circuit can carry the current necessary to operate the component. See GROUND DISTRIBUTION in appropriate SYSTEM WIRING DIAGRAMS article in ELECTRICAL.

Temperature Sensitivity

  1. An intermittent condition may occur when a component or connection reaches normal operating temperature. The condition may occur only when the component or connection is cold, or only when the connection is hot.
  2. The following data may help to diagnose this type of intermittent condition: Freeze Frame/Failure Records. Scan tool snapshot. Vehicle data recorder.
  3. If the intermittent is related to heat, review the following data: High ambient temperatures. Underhood or engine generated heat. Circuit generated heat due to a poor connection, or high electrical load. Higher than normal load conditions, such as towing.
  4. If the intermittent is related to cold, review the following data: 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 is not present after 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 (EMI) & Electrical Noise

Some electrical components or circuits are sensitive to Electromagnetic Interference (EMI) or other types of electrical noise. Perform the following procedures

  1. Check for a misrouted harness that is too close to a high voltage or high current device. This condition may induce electrical noise on a circuit that could interfere with normal circuit operation. Check for wires that are too close to the following devices: Secondary ignition components. Motors. The generator.
  2. Determine whether the electrical system interference is caused by a malfunctioning relay, PCM driven solenoid or switch. These components may cause a sharp electrical surge. Normally, the problem will occur when the malfunctioning component is operating.
  3. Determine whether non-factory or aftermarket add-on accessories are installed in the vehicle. These accessories may lead to an emission related OBD-II failure. Determine if any of the following non-factory or aftermarket add-on accessories is causing the intermittent: Lights. 2-way radios. Amplifiers. Electric motors. Remote starters. Alarm systems. Cell phones.
  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. See ON-VEHICLE TESTING in appropriate GENERATORS & REGULATORS article in ELECTRICAL.

Incorrect PCM Programming

  1. There are only a few situations when reprogramming a PCM is appropriate, such as the following: A new service PCM is installed. A PCM from another vehicle is installed. Revised software or calibration files have been released for this vehicle.
  2. Verify that the PCM contains the correct software or calibration. If incorrect programming is found, reprogram the PCM with the most current software or calibration. See «POWERTRAIN CONTROL MODULE»(ref-156775-S37360666392003072900000) under PROGRAMMING in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.

Duplicating Failure Conditions

  1. If none of the previous tests are successful, attempt to duplicate or capture the failure conditions.
  2. Freeze Frame/Failure Records data, where applicable, contains the conditions that were present when the DTC set. Perform the following procedure: Review and record Freeze Frame/Failure Records data. Clear the DTCs using the scan tool. Turn the key to OFF and wait 15 seconds. 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 DTC in the supporting text of the DTC being diagnosed. Monitor DTC Status for the DTC being tested. The scan tool will indicate RAN, when the enabling conditions have been satisfied long enough for the DTC to run. The scan tool will also indicate whether the DTC passed or failed.
  3. An alternate method is to drive the vehicle with the Digital Multimeter (DMM) connected to a suspected circuit. An abnormal reading on the DMM when the problem occurs, may help you locate the problem.

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.

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