Engine Controls - Basic Testing 3.0: Other Infiniti I30 I

Compression

Check engine compression at normal operating temperature at specified cranking speed. Release fuel pressure. See FUEL SYSTEM. Disconnect crankshaft position sensor harness connector. Remove all spark plugs. Depress accelerator pedal fully to hold throttle valve wide open. See COMPRESSION SPECIFICATIONS table.

Note. If cylinder compression in one or more cylinders is low, repeat inspection using a small amount of oil poured into each cylinder. If compression pressure increases, piston rings may be worn or damaged. If compression pressure does not increase, a valve may be sticking or seating improperly. If compression in any 2 adjacent cylinders is low and does not change after oil is added, there is a leak past head gasket. Make repairs as needed and reinspect.

COMPRESSION SPECIFICATIONS (1)

Exhaust System Backpressure

Exhaust system can be checked with a vacuum gauge or a pressure gauge. Remove HO2S sensor. Connect a 1-5 psi pressure gauge, and run engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.

If a vacuum gauge is used, connect it to intake manifold vacuum. Observe vacuum gauge reading at idle. Open throttle part way (about 2500 RPM) and hold steady. If vacuum gauge slowly drops after stabilizing, exhaust system should be checked for a restriction.

FUEL PRESSURE

Basic diagnosis of fuel system should begin with determining fuel system pressure.

Relieving Fuel Pressure

To relieve pressure, remove fuel pump fuse, start engine and allow to run until engine stalls due to lack of fuel. Crank engine 2-3 more times to verify all pressure has dissipated.

Checking Fuel Pressure

1. Disconnect fuel hose on fuel filter outlet side and install fuel pressure gauge. Replace pump fuse. Start engine and check fuel line connections for leakage. Check fuel pressure with engine idling. Record fuel pressure gauge reading.
2. Disconnect and plug vacuum hose from pressure regulator and immediately note fuel pressure. Record fuel pressure gauge reading. See FUEL PRESSURE table.
3. Connect a hand-held vacuum pump to fuel pressure regulator. Start engine and watch fuel pressure gauge as vacuum is changed. Fuel pressure should decrease as vacuum increases. If result is not as specified, replace fuel pressure regulator.

FUEL PRESSURE (At Idle)

DISTRIBUTORLESS IGNITION SYSTEM CHECKS

To determine cause of a no-spark condition, following steps must be performed in order given. Deviation from this procedure may cause false diagnosis and replacement of non-defective components.

Ignition Coil Power Source

1. Turn ignition off. Disconnect ignition coil harness connector. Turn ignition on. Connect negative voltmeter lead to ground and individually connect positive lead to each Red wire. Battery voltage should be present on each circuit.
2. If battery voltage is not present, turn ignition off and check harness continuity between ignition coil and fuse block. If continuity is present, check continuity of Black/Red wire between fuse block and ignition switch.

Ground Circuit

Disconnect ignition coil harness connector. Check continuity between Black wire on harness connectors and ground. Continuity should be present. If continuity is not present, check harness connector between ignition coil and ground.

Output Signal Circuit

See DTC P1320 - IGNITION SIGNAL in appropriate TESTS W/CODES article and go to step 2).

ECCS Relay

1. Remove ECCS relay. (Scheme 74) Connect a 12-volt power source and ground to terminals No. 1 and 2 of relay. (Scheme 73) Using ohmmeter, check continuity between terminals No. 3 and 5. Continuity should exist while relay is energized.
2. Disconnect power source and repeat continuity check. No continuity should exist. If continuity is not as specified, replace ECCS relay.

Scheme 73

Scheme 74

Ignition Coil Resistance

Disconnect ignition coil harness connector. Using ohmmeter, check for continuity between coil terminals No. 1 and 2. If continuity is not present, replace ignition coil. (Scheme 75)

Scheme 75

Power Transistor

Disconnect power transistor harness connector. Using ohmmeter, check power transistor continuity. Replace power transistor if results are not as specified.

Note. Power transistor is integrated with the ignition coil.

Camshaft Position (CMP) Sensor

See DTC P0340 - CAMSHAFT POSITION (CMP) SENSOR in appropriate TESTS W/CODES article and go to step 3).

Crankshaft Position (CKP) Sensor

See step 4) of DTC PO335 & P1336 - CRANKSHAFT POSITION (CKP) SENSOR in appropriate TESTS W/CODES article.

IDLE SPEED

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

IDLE SPEED & CO LEVEL

IGNITION TIMING (Degrees BTDC @ Idle)

SUMMARY

If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to TESTS W/CODES article. If no hard codes are found in self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.