Diagnosis Procedure

Check the following.

• Connection condition of the ground F59 and F60
• Connection condition of the ground harness between engine assembly and vehicle body (If equipped)

Is the inspection result normal?

YES

GO TO 2

NO

Repair or replace error-detected parts.

1. Start engine and run it at idle speed.
2. Listen for the sound of the intake air leak.
3. Check PCV hose connection.

Is intake air leak detected?

YES

Discover air leak location and repair.

NO

GO TO 3.

Stop engine and visually check exhaust tube, three way catalyst and muffler for dents.

Is the inspection result normal?

YES

With CONSULT: GO TO 4.

YES

Without CONSULT: GO TO 5.

NO

Repair or replace it.

With CONSULT

1. Start engine.
2. Perform "POWER BALANCE" in "Active Test" mode of "ENGINE".
3. Make sure that each circuit produces a momentary engine speed drop.

Is the inspection result normal?

YES

GO TO 10.

NO

GO TO 5.

1. Start engine and let it idle.
2. Listen to each fuel injector operation sound.

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   Clicking sound should be heard.

Is the inspection result normal?

YES

GO TO 6.

NO

Perform trouble diagnosis for FUEL INJECTOR, refer to Diagnosis Procedure .

1. Turn ignition switch OFF.
2. Pull out 15A fuse (No. 47) from IPDM E/R to release fuel pressure. Refer to IPDM E/R Terminal Arrangement .
   NOTE: Do not use CONSULT to release fuel pressure, or fuel pressure applies again during the following procedure.
3. Start engine.
4. After engine stalls, crank it two or three times to release all fuel pressure.
5. Turn ignition switch OFF.
6. Remove all ignition coil harness connectors to avoid the electrical discharge from the ignition coils.
7. Remove ignition coil and spark plug of the cylinder to be checked.
8. Crank engine for 5 seconds or more to remove combustion gas in the cylinder.
9. Connect spark plug and harness connector to ignition coil.
10. Fix ignition coil using a rope etc. with gap of 13 - 17 mm (0.52 - 0.66 in) between the edge of the spark plug and grounded metal portion as shown in the figure.

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11. Crank engine for about 3 seconds, and check whether spark is generated between the spark plug and the grounded metal portion.

    Spark should be generated.

    CAUTION:

    • Never place the spark plug and the ignition coil within 50 cm (19.7 in) each other. Be careful not to get an electrical shock while checking, because the electrical discharge voltage becomes 20 kV or more.
    • It might damage the ignition coil if the gap of more than 17 mm (0.66 in) is made.
    NOTE: When the gap is less than 13 mm (0.52 in), a spark might be generated even if the coil is malfunctioning.

Is the inspection result normal?

YES

GO TO 10.

NO

GO TO 7.

1. Turn ignition switch OFF.
2. Disconnect spark plug and connect a non-malfunctioning spark plug.
3. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and the grounded metal portion.

   Spark should be generated.

Is the inspection result normal?

YES

GO TO 8.

NO

Check ignition coil, power transistor and their circuits. Refer to Diagnosis Procedure .

Check the initial spark plug for fouling, etc.

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Is the inspection result normal?

YES

Replace spark plug(s) with standard type one(s). For spark plug type, refer to SPARK PLUG .

NO

Repair or clean spark plug. Then GO TO 9.

1. Reconnect the initial spark plugs.
2. Crank engine for about 3 seconds, and recheck whether spark is generated between the spark plug and the grounded portion.

   Spark should be generated.

Is the inspection result normal?

YES

INSPECTION END

NO

Replace spark plug(s) with standard type one(s). For spark plug type, refer to SPARK PLUG .

Check compression pressure. Refer to COMPRESSION PRESSURE .

Is the inspection result normal?

YES

GO TO 11.

NO

Check pistons, piston rings, valves, valve seats and cylinder head gaskets.

1. Install all removed parts.
2. Release fuel pressure to zero. Refer to Work Procedure .
3. Install fuel pressure gauge and check fuel pressure. Refer to Work Procedure .

Is the inspection result normal?

YES

GO TO 13.

NO

GO TO 12.

Check fuel hoses and fuel tubes for clogging.

Is the inspection result normal?

YES

Replace "fuel filter and fuel pump assembly".

NO

Repair or replace.

For procedure, refer to Work Procedure .

For specification, refer to Idle Speed and Ignition Timing .

Is the inspection result normal?

YES

GO TO 14.

NO

Follow the Work Procedure .

1. Turn ignition switch OFF.
2. Disconnect corresponding A/F sensor 1 harness connector.
3. Disconnect ECM harness connector.
4. Check the continuity between A/F sensor 1 harness connector and ECM harness connector.

   Bank	A/F sensor 1		ECM		Continuity
   	Connector	Terminal	Connector	Terminal
   1	F72	3	F79	102	Existed
   		4		101
   2	F73	3		111
   		4		107

5. Check the continuity between A/F sensor 1 harness connector and ground, or ECM harness connector and ground.

   Bank	A/F sensor 1		--	Continuity
   	Connector	Terminal
   1	F72	3	Ground	Existed
   		4
   2	F73	3
   		4

   Bank	ECM		--	Continuity
   	Connector	Terminal
   1	F79	101	Ground	Existed
   		102
   2		107
   		111

6. Also check harness for short to power.

Is the inspection result normal?

YES

GO TO 15.

NO

Repair open circuit, short to ground or short to power in harness or connectors.

Refer to Component Inspection (A/F Sensor 1 Heater) .

Is the inspection result normal?

YES

GO TO 16.

NO

Replace (malfunctioning) A/F sensor 1. Refer to EXHAUST MANIFOLD AND THREE WAY CATALYST .

With CONSULT

Check "MASS AIR FLOW SENSOR (Hz)" in "Data Monitor" mode of "ENGINE".

For specification, refer to Mass Air Flow Sensor .

With GST

Check mass air flow sensor signal in Service $01 with GST.

For specification, refer to Mass Air Flow Sensor .

Is the measurement value within the specification?

YES

GO TO 17.

NO

Check connectors for rusted terminals or loose connections in the mass air flow sensor circuit or ground. Refer to Diagnosis Procedure .

Check items on the rough idle symptom in Symptom Table .

Is the inspection result normal?

YES

GO TO 18.

NO

Repair or replace.

Some tests may cause a 1st trip DTC to be set.

Erase the 1st trip DTC from the ECM memory after performing the tests. Refer to CONSULT Function (With CONSULT).

INSPECTION END