Engine Controls - Basic Testing: Other Infiniti Q45 II

RETRIEVE & RECORD CODES

Prior to conducting a physical mechanical inspection, retrieve and record any Diagnostic Trouble Codes (DTCs) that are currently set in Powertrain Control Module (PCM) memory. See RETRIEVING CODES in SELF-DIAGNOSTICS - INTRODUCTION article. Record any DTCs that are present at this time. Review recovered DTCs, if set, or if battery is disconnected or other DTCs are set during mechanical inspection portion of basic diagnostic procedures.

Compression (I30)

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.

Compression (Q45)

Check engine compression at normal operating temperature at specified cranking speed. Release fuel pressure. See FUEL SYSTEM . Remove left air duct and disconnect power transistor connectors. Remove left harness connector bracket and ornamental rocker covers. Disconnect harness connector between ignition coil and power transistor. Remove ignition coil bracket and bracket with ignition coils. 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.

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»(ref-18054-S24639867382000122900000) 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 DVOM negative lead to ground and proceed as follows: On I30, individually connect positive lead to each Red wire. On Q45, individually connect positive lead to each Black/White wire. On all models, battery voltage should be present on each circuit.
2. If battery voltage is not present, turn ignition off and proceed as follows: On I30, 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. On Q45, check 30-amp fuse in fuse box. If fuse is okay, check harness continuity between ignition coil and ignition switch, and harness continuity of White/Black wire between ignition switch and battery.

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 articles below

1. For I30, see «TESTS W/CODES»(ref-18055) article.
2. For Q45, see «TESTS W/CODES»(ref-18053) article.

ECCS Relay (I30 & Q45)

1. Remove ECCS relay. (Scheme 2)or (Scheme 3). Connect a 12-volt power source and ground to terminals No. 1 and 2 of relay. (Scheme 1) 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 1

Scheme 2

Scheme 3

Ignition Coil Resistance

1. On I30, 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 4)
2. On Q45, disconnect ignition coil harness connector. Using ohmmeter, check resistance between coil terminals No. 1 and 2 (cylinders No. 1 and 2) and terminals No. 2 and 3 (cylinders No. 3 and 8). (Scheme 5) Resistance should be approximately.7 ohm. If resistance is not as specified, replace ignition coil.

Scheme 4

Scheme 5

Camshaft Position (CMP) Sensor

See DTC P0340: CAMSHAFT POSITION (CMP) SENSOR in appropriate TESTS W/CODES articles below

1. For I30, see «TESTS W/CODES»(ref-18055) article.
2. For Q45, see «TESTS W/CODES»(ref-18053) article.

Crankshaft Position (CKP) Sensor

See DTC P0335 & P1336: CRANKSHAFT POSITION (CKP) SENSOR in appropriate TESTS W/CODES articles belo

1. For I30, see «TESTS W/CODES»(ref-18055) article.
2. For Q45, see «TESTS W/CODES»(ref-18053) 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 articles below. If no DTC is found performing self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

1. For I30, see «TESTS W/CODES»(ref-18055) article.
2. For Q45, see «G - TESTS W/CODES»(ref-18053) article.