Engine Controls - Tests W/o Codes: Other Infiniti J30 I

Preliminary Checks

Check battery connections and condition. Check for vacuum and intake air leaks. Check fuel pressure and ensure fuel is of good quality.

Engine Cold

Perform the following in order

1. Check IACV-air regulator, IACV-AAC valve. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
2. Check injector operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
3. Check ignition spark and spark plugs.
4. Inspect harness connector for damaged pins or poor connection.
5. Check ECM power supply and ground.
6. Replace ECM with known good unit.

Engine At Operating Temperature

Perform the following in order

1. Check fuel injectors for leakage. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
2. Check fuel injector operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
3. Check ignition spark and spark plugs.
4. Check EGR valve for stuck open condition.
5. Inspect ECM harness connector for damaged pins or poor connection.
6. Check ECM power supply and ground.
7. Replace ECM with known good unit.

Engine Hot

Perform the following in order

1. Check for fuel vapor lock. Disconnect pressure regulator hose and attempt to start engine.
2. Check fuel injector operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
3. Check ignition spark and spark plugs.
4. Inspect ECM harness connector for damaged pins or poor connection.
5. Check ECM power supply and ground.
6. Replace ECM with known good unit.

Check condition of spark plugs. Check for vacuum and intake air leaks.

Perform the following in order

1. Replace mass airflow sensor with known good unit.
2. Check for excessive carbon on intake valves.

Perform the following in order

1. Check oxygen sensor. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
2. Disconnect and plug canister purge hose and recheck symptom.

Perform the following in order

1. Check for fuel vapor lock. Disconnect pressure regulator hose and attempt to start engine.
2. Disconnect and plug canister purge hose and recheck symptom.

Check for vacuum and intake air leaks.

1. Check IACV-air regulator. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
2. Check throttle linkage for sticking or binding.

FLUCTUATING IDLE SPEED (HUNTING)

1. Check heated oxygen sensor(s). See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
2. Perform power balance test.
3. Check spark plugs.
4. Check for intake air leak.
5. Check EGR valve for sticking.

UNSTABLE IDLE

1. Check EGR valve for sticking.
2. Perform power balance test.
3. Check ignition spark.
4. Check condition of spark plugs.
5. Check fuel pressure. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
6. Check heated oxygen sensor(s). See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
7. Check for intake air leak.
8. Check idle speed adjuster screw for clogging. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
9. Check compression of engine.
10. Inspect ECM harness connector for damaged pins or poor connection.
11. Replace ECM with known good unit.

Perform the following in order

1. Check IACV-AAC valve and IACV-air regulator. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
2. Perform power balance test.
3. Check fuel injector operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
4. Check ignition spark.
5. Check condition of spark plugs.
6. Check fuel pressure. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
7. Inspect ECM harness connector for damaged pins or poor connection.
8. Check ECM power supply and ground.
9. Replace ECM with known good unit.

Perform the following in order

1. Check for fuel vapor lock. Disconnect pressure regulator hose and recheck symptom.
2. Perform power balance test.
3. Check fuel injector operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
4. Check ignition spark.
5. Check fuel pressure. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
6. Inspect ECM harness connector for damaged pins or poor connection.
7. Check ECM power supply and ground.
8. Replace ECM with known good unit.

On Deceleration

Perform the following in order

1. Check IACV-AAC valve and IACV-air regulator. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
2. Perform power balance test.
3. Check fuel injector operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
4. Check ignition spark.
5. Check fuel pressure. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
6. Check oxygen sensor. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
7. Inspect ECM harness connector for damaged pins or poor connection.
8. Check ECM power supply and ground.
9. Replace ECM with known good unit.

LACK OF POWER

1. Check fuel pressure. See BASIC TESTING article in the ENGINE PERFORMANCE Section.
2. Check for intake air leak.
3. Check timing belt installation.

Check for intake air leaks. Check ignition timing. See BASIC TESTING article in the ENGINE PERFORMANCE Section.

1. Check EGR operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
2. Check EGR control solenoid valve. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
3. Check vacuum hoses for leakage or misrouting. See VACUUM DIAGRAMS article in the ENGINE PERFORMANCE Section.
4. Check spark plugs for evidence of excessive oil consumption.

SURGING

1. Check oxygen sensor(s).
2. Check EGR operation. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.
3. Replace ECM with known good unit.

BACKFIRE THROUGH INTAKE

1. Check condition of spark plugs.
2. Check for intake air leaks.
3. Check intake valves for excessive carbon deposits.

BACKFIRE THROUGH EXHAUST

1. Check coolant temperature sensor. See I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section.

Intermittent Simulation

To reproduce conditions creating an intermittent fault, use the following methods

1. Lightly vibrate component.
2. Heat component. (Use light bulb or heat gun, DO NOT use open flame).
3. Wiggle or bend wiring harness.
4. Spray component with water.
5. Remove/apply vacuum source.

Monitor circuit/component voltage or resistance while simulating intermittent. If engine is running, monitor for self-diagnostic codes. Use test results to identify a faulty component or circuit.