Engine Controls - Basic Engine Testing - 3.1L: Other Oldsmobile Cutlass VI

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions. For compression specifications, see the SPECIFICATIONS article.

Exhaust System Backpressure

Before replacing any components, check exhaust system for restrictions. Use a vacuum gauge or a low-pressure (0-5 psi) gauge to check exhaust system.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Partially open throttle and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction. If using a low pressure gauge, connect gauge in one of the following manners

1. Check At AIR Check Valve Remove AIR check valve. Install backpressure tester in place of AIR check valve.
2. Check At Oxygen Sensor Remove oxygen sensor. Install backpressure tester in place of oxygen sensor. After test is completed, coat oxygen sensor threads with anti-seize compound before installation.

DEFINITION

No start is defined as engine cranks properly, but does not start. Engine may fire a few times.

NO START - ENGINE CRANKS OKAY

Note. Check battery, engine cranking speed and fuel supply before performing the following tests.

Ignition System

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . After performing OBD system check, go to next step.
2. Turn ignition on. Using scan tool, select FAILED SINCE CODE CLEAR function. If Diagnostic Trouble Code (DTC) P0101, P0123, P0601/P0602, P1200, P1374, P1626 or P1629 is present, diagnose applicable DTC. See the TESTS W/CODES article. If DTC is not present, go to next step.
3. Turn ignition on with engine off. Using scan tool, monitor Manifold Absolute Pressure (MAP) sensor. If MAP sensor value is less than 65 kPa, go to step 27). If MAP sensor value is more than 65 kPa, go to next step.
4. Turn ignition off. Disconnect MAP sensor connector. Attempt to start engine. If engine starts and continues to run, go to step 27). If engine does not start, go to next step.
5. Turn ignition off. Reconnect MAP sensor connector. Install fuel pressure gauge. Turn ignition on and observe fuel pressure. Fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ). If fuel pressure is as specified, go to step 7). If fuel pressure is not as specified, go to next step.
6. If fuel pressure is present, but not as specified, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(ref-20651-S13418260072001010200000) . If fuel pressure is not present, go to FUEL SYSTEM.
7. Turn ignition off. Disconnect 10-pin fuel injector/engine connector. Using a test light connected to battery voltage, probe each injector driver circuit while cranking engine. If test light flashes, go to next step. If test light does not flash, go to step 9).
8. Remove fuel injection fuse from underhood fuse block. Install Spark Tester (J-26792) to cylinder No. 2, 4 and 6 (one at a time). Connect the spark plug wire of companion cylinder to ground. Crank engine and observe spark tester. If spark is present, go to step 19). If spark is not present, go to step 11).
9. Check fuel injector feed circuit fuse. If fuse is faulty, check for a short to ground in injector feed circuit, or shorted injector. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If circuit and injector are okay, go to next step.
10. Check for open in fuel injector feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
11. Check fuse to Ignition Control Module (ICM) ignition feed circuit. If fuse is faulty, check for short to ground in ICM feed circuit or short to voltage in IC control circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If fuse is okay, go to next step.
12. Check for open in ICM feed and ground circuits. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If circuits are okay, go to next step.
13. Disconnect 7X Crankshaft Position (CKP) sensor connector from ICM. Connect DVOM between CKP sensor connector terminals. Set DVOM to 2-volt AC scale. Crank engine and observe DVOM. DVOM should read about 2-volts AC. If voltage is as specified, go to step 15). If voltage is not as specified, go to next step.
14. Turn ignition off. Check 7X CKP sensor circuit for open or short to voltage or ground. Check for poor 7X CKP sensor connection. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If circuit is okay, go to step 28).
15. Check for poor ICM connection. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If connection is okay, go to next step.
16. Remove and inspect coil that did not produce a spark. Check for cracks or carbon tracking. Replace as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If coil(s) are okay, go to next step.
17. Check secondary resistance of ignition coil that did not produce a spark. Resistance should be 5000-8000 ohms. If resistance is not as specified, replace ignition coil. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If coil resistance is as specified, go to next step.
18. Connect a test light across affected ICM primary terminals. Crank engine and observe test light. If test light flashes while cranking engine, go to step 29). If test light does not flash, go to step 30).
19. Check cylinders No. 2, 4 and 6 spark plug wires. Check for carbon tracking or damaged insulation. Replace as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If wire(s) are okay, go to next step.
20. Check spark plug wire resistance of cylinders No. 2, 4 and 6. Resistance should be 8000 ohms. If resistance is not as specified, replace wire(s). After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If wire(s) are okay, go to next step.
21. Remove spark plugs from cylinders No. 2, 4 and 6. Check spark plug electrodes for excessive fouling. If excessive fouling is present, go to step 26). If excessive fouling is not present, go to next step.
22. Check cylinders No. 1, 3 and 5 spark plug wires. Check for carbon tracking or damaged insulation. Replace as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If wire(s) are okay, go to next step.
23. Check spark plug wire resistance of cylinders No. 1, 3 and 5. Resistance should be 8000 ohms. If resistance is not as specified, replace wire(s). After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If wire(s) are okay, go to next step.
24. Remove spark plugs from cylinders No. 1, 3 and 5. Check spark plug electrodes for excessive fouling. If excessive fouling is present, go to step 26). If excessive fouling is not present, go to next step.
25. Test fuel for contamination. If fuel is contaminated, clean fuel system. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If fuel is not contaminated, check for poor or damaged PCM connector, for faulty engine coolant temperature sensor, or mass airflow miscalculated due to faulty throttle position sensor or manifold absolute pressure sensor. See the SYSTEM/COMPONENT TESTS article.
26. Check for engine mechanical problem. Check for bent push rods, faulty camshaft, leaking or sticky valves or rings, excessive valve deposits, loose or worn rocker arms, weak valve springs, incorrect valve timing or leaking head gasket. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
27. Replace MAP sensor. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
28. Replace 7X CKP sensor. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
29. Replace ignition coil(s) associated with cylinder that did not produce a spark. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
30. Replace ICM. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
31. Replace PCM. Perform PCM relearn procedures. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . Fuel System

Fuel System

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . After performing OBD system check, go to next step.
2. Turn ignition off. Install fuel pressure gauge to fuel pressure test port. Remove fuel pump relay. Using a fused jumper wire, jumper fuel pump feed circuit at fuel pump relay connector to battery voltage. See the WIRING DIAGRAMS article. Fuel pressure should be 41-47 psi (2.9-3.3 kg/cm 2 ). If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to step 10).
3. Disconnect jumper from fuel pump relay connector. Connect test light between fuel pump relay connector terminals for ignition feed circuit and ground circuit. See the WIRING DIAGRAMS article. Turn ignition on. If test light illuminates, go to next step. If test light does not illuminate, go to step 9).
4. Turn ignition off. Connect test light between fuel pump relay connector terminals for fuel pump relay driver circuit and ground circuit. See the WIRING DIAGRAMS article. Turn ignition on. Test light should illuminate for about 2 seconds. If test light illuminates, go to step 8). If test light does not illuminate, go to next step.
5. Turn ignition off. Disconnect PCM connector. Using a test light connected to battery voltage, probe fuel pump driver circuit at PCM connector. If test light illuminates, go to step 15). If test light does not illuminate, go to next step.
6. Check continuity between fuel pump relay driver circuit between PCM and fuel pump relay. See the WIRING DIAGRAMS article. If circuit is open, repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If circuit is okay, go to next step.
7. Check fuel pump relay driver circuit for poor terminal connection at PCM. If connection is faulty, repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If connection is okay, go to step 20).
8. Check for poor fuel pump relay terminal connection. If connection is faulty, repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If connection is okay, go to step 18).
9. Using a test light connected to ground, probe ignition feed circuit at fuel pump relay connection. See the WIRING DIAGRAMS article. If test light illuminates, go to step 17). If test light does not illuminate, go to step 16).
10. Remove fuel filler cap and listen for fuel pump operation. If fuel pump is running, diagnose fuel system. See «BASIC FUEL SYSTEM CHECKS»(ref-20651-S13418260072001010200000) . If fuel pump is not running, go to next step.
11. Using a fused jumper wire connected to battery voltage, jumper fuel pump feed circuit. See the WIRING DIAGRAMS article. Raise and support vehicle. Disconnect fuel sending unit connector at fuel tank. Using a test light, check circuit between fuel sending unit connector. If test light illuminates, go to step 19). If test light does not illuminate, go to next step.
12. Using a test light connected to ground, probe fuel pump feed circuit at fuel sending unit connector. See the WIRING DIAGRAMS article. If test light does not illuminate, go to next step. If test light illuminates, go to step 14).
13. Locate and repair open in fuel pump feed circuit. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
14. Locate and repair open in fuel pump ground circuit. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
15. Locate and repair short to ground in fuel pump relay driver circuit. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
16. Locate and repair open in ignition feed circuit to fuel pump relay. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
17. Locate and repair open in ground circuit to fuel pump relay. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
18. Replace fuel pump relay. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
19. Replace fuel pump. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
20. Replace PCM. Perform PCM relearn procedures. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .

BASIC FUEL SYSTEM CHECKS

Fuel Pressure Relief

Fuel system is under pressure. Pressure must be relieved prior to servicing fuel system. Fuel pressure may be relieved by using one of the following methods

1. Disconnect negative battery terminal. Loosen fuel filler cap. Install Fuel Pressure Gauge (J-34730-1) on fuel pressure connector of fuel rail. Wrap shop towel around pressure connection when installing fuel pressure gauge to absorb fuel leakage. Install gauge bleed hose in container. Open bleed valve to bleed fuel pressure.

Fuel Pressure Check

1. Relieve fuel pressure. See FUEL PRESSURE RELIEF. Connect Fuel Pressure Gauge (J-34730-1) to fuel pressure fitting on fuel rail. Turn ignition on with engine off. Fuel pressure should be within specification. See «FUEL PRESSURE»(ref-20651-S27024007592001010200000) table. If no fuel pressure is present, go to step 5).
2. Start engine. Fuel pressure should drop 3-10 psi (.2-.7 kg/cm 2 ). Turn ignition off. Pressure should hold. If fuel pressure does not hold, check for leaking injectors or fittings. If injectors or fittings are not leaking, replace fuel pressure regulator.
3. If fuel pressure is less than specified, check for restricted fuel line or fuel filter. Repair as necessary. If no restriction is evident, apply battery voltage to fuel pump test connector using a 10-amp fused jumper wire. For location of fuel pump test connector, see COMPONENT LOCATIONS in the SYSTEM/COMPONENT TESTS article.
4. Gradually pinch off fuel return line between gauge and fuel tank. If fuel pressure increases to within specification, replace fuel pressure regulator. If fuel pressure does not increase with line pinched, check for faulty in-tank fuel pump or partially blocked fuel strainer.
5. Using a 10-amp fused jumper wire, apply battery voltage to fuel pump test connector. For location of fuel pump test connector, see COMPONENT LOCATIONS in the SYSTEM/COMPONENT TESTS article. Observe fuel pressure reading. If fuel pressure is still not present, check wiring between test connector and fuel pump. If wiring is okay, replace fuel pump.
6. If fuel pressure is present with voltage applied to test connector, test fuel pump relay and voltage supply to relay. See the SYSTEM/COMPONENT TESTS article.

FUEL PRESSURE

Fuel Pump Relay

See MOTORS, RELAYS & SOLENOIDS in the SYSTEM/COMPONENT TESTS article.

Fuel Pump Relay By-Pass Procedure

See FUEL DELIVERY in the SYSTEM/COMPONENT TESTS article.

Spark

1. If factory tachometer is connected to coil tachometer terminal, disconnect tachometer before performing tests. When removing spark plug wire from spark plug, twist and pull on boot. DO NOT pull on wire.
2. Using Spark Tester (J-26792), check for spark at each spark plug wire. Leave other wires connected while checking for spark. Check spark plug wire resistance on suspect wires. Resistance should be about 30,000 ohms.

Ignition Coil Power Source

Turn ignition on. Check ignition positive voltage circuit of ignition control module for battery voltage. See the WIRING DIAGRAMS article. If battery voltage is not present, check ignition or PCM fuse. If fuse is not blown, check for open between fuse and ignition control module.

Ignition Coil Resistance

If ignition coil is suspected of causing misfire or no-spark condition, switch coil locations on ignition control module. If problem follows questionable coil, check ignition coil resistance or replace original coil. For ignition coil resistance, see IGNITION COIL RESISTANCE table.

IGNITION COIL RESISTANCE

Crankshaft Position (CKP) Sensor Pick-Up Coil Short & Resistance Checks

1. Set DVOM on 2000-ohm scale position. Connect DVOM leads to CKP sensor connector located on side of engine block. Turn ignition off. Disconnect ignition control module connectors. Check resistance between CKP sensor terminals at ignition control module connector.
2. CKP sensor resistance should be within specification range. See CRANKSHAFT POSITION (CKP) SENSOR RESISTANCE table. If resistance is not as specified, replace CKP sensor. If sensor is within specification, go to next step.
3. With CKP sensor installed in block, connect one ohmmeter lead to either sensor terminal at ignition control module. Touch other lead of ohmmeter to engine block. No continuity should exist. If continuity exists, CKP sensor is shorted to ground and must be repaired or replaced.

CRANKSHAFT POSITION (CKP) SENSOR RESISTANCE (1)

Crankshaft Position (CKP) Sensor Output Signal

Set DVOM on 2-volt AC scale. Connect DVOM leads to CKP sensor located on side of engine block. Crank engine and observe voltmeter reading. CKP sensor should generate a voltage signal of about 2 volts.

Tach Pulse (RPM) Signal

Connect scan tool to DLC. RPM should be indicated on scan tool when engine is cranked or running. Tach pulse (RPM reference) will be indicated as a voltage signal when a DVOM (with a minimum 10-megohm input impedance connected to ground) is used to backprobe RPM high reference circuit. For circuit and terminal identification, See the WIRING DIAGRAMS article.

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see the ADJUSTMENTS article.

MIL INOPERATIVE

1. Perform On-Board Diagnostic (OBD) System Check. See «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . After performing OBD system check, go to next step.
2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 6).
3. Check instrument cluster ignition feed fuse. If fuse is okay, go to next step. If fuses are blown, go to step 15).
4. Turn ignition on. Using a test light connected to ground, probe instrument cluster connector ignition feed circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 12).
5. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using a jumper wire connected to ground, jumper PCM connector MIL driver circuit. See the WIRING DIAGRAMS article. If MIL illuminates, go to step 10). If MIL does not illuminate, go to step 11).
6. Check PCM ignition feed and battery feed fuses. If fuses are okay, go to next step. If fuses are blown, go to step 14).
7. Turn ignition off. Disconnect PCM connector. Turn ignition on. Using a test light connected to ground, probe PCM connector ignition feed circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
8. Using a test light connected to ground, probe PCM connector battery feed circuit. See the WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 13).
9. Check for poor PCM ground or PCM ground connection. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If ground and ground connection are okay, go to next step.
10. Check for poor PCM connection. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If connection is okay, go to step 16).
11. Check for open in MIL driver circuit. See the WIRING DIAGRAMS article. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If circuit is okay, go to step 17).
12. Repair open in instrument cluster ignition feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
13. Locate and repair open in PCM battery feed circuit or PCM ignition feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
14. Locate and repair short to ground in PCM battery feed circuit or PCM ignition feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
15. Locate and repair short to ground in instrument cluster ignition feed circuit. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
16. Replace PCM. Perform PCM relearn procedures. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) .
17. Check for poor instrument cluster MIL driver circuit connection. Repair as necessary. After repairs, perform «ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK»(ref-20651-S05911687882001010200000) . If connection is okay, diagnose instrument cluster.

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, no trouble codes (or only intermittent ones) were found while performing ON-BOARD DIAGNOSTIC SYSTEM CHECK and driveability problems exist, proceed to the TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO-START, etc.) or intermittent diagnostic procedures.