Diagnostic procedure

WARNING: This page is about a different car, the 2005 Mazda 6. However, it is still accessible from the selected car via links, so may be relevant.

NO. 19 EXHAUST SMOKE DIAGNOSTIC PROCEDURE

STEP	INSPECTION	RESULTS	ACTION
1	What color is smoke coming from exhaust system?	Blue	Burning oil is indicated. Go to the next step.
		White	Water in combustion is indicated. Go to Step 3.
		Black	Rich fuel mixture is indicated. Go to Step 4.
2	Remove and shake PCV valve. Does PCV valve rattle	Yes	Inspect for the following: Damaged valve guide, stems or valve seals Blocked oil drain passage in cylinder head Piston ring is not seated, seized or worn. Damaged cylinder bore If other driveability symptoms are present, return to diagnostic index to service any additional symptoms.
2	Remove and shake PCV valve. Does PCV valve rattle	No	Replace PCV valve.
3	Does cooling system hold pressure?	Yes	Inspect for the following: Cylinder head gasket leakage Intake manifold gasket leakage Cracked or porous engine block If other driveability symptoms are present, return to diagnostic index to service any additional symptoms.
3	Does cooling system hold pressure?	No	Inspect for cause.
4	Inspect for the following: Air cleaner restriction Collapsed or restricted intake-air system Restricted fuel return line Are all items normal?	Yes	Go to the next step.
4		No	Service if necessary.
5	Connect WDS or equivalent to DLC-2. Turn ignition switch to ON position (Engine off). Retrieve any DTCs. Are there any DTCs displayed?	Yes	DTC is displayed: Go to appropriate DTC test. Repeat Step 4.
5		No	No DTC is displayed: Go to the next step.
6	Install fuel pressure gauge between fuel pipe and fuel distributor. Start engine and idle it. Measure fuel line pressure during idle. Is fuel line pressure correct during idle? (See FUEL LINE PRESSURE INSPECTION .)	Yes	Go to the next step.
6		No	Zero or low: Inspect for clogged fuel line. If okay, replace fuel pump unit. High: Replace fuel pump unit.
7	Perform Spark Test. (See SPARK TEST (CALIFORNIA EMISSION REGULATION APPLICABLE ATX MODEL) .) (See SPARK TEST (EXCEPT FOR CALIFORNIA EMISSION REGULATION APPLICABLE ATX MODEL) .) Is the strong blue spark visible at each cylinder?	Yes	Inspect spark plugs and CMP sensor.
7		No	Repair or replace malfunctioning part according to spark test results.
8	Verify test results. If okay, return to diagnostic index to service any additional symptoms. If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis. If vehicle is repaired, troubleshooting completed. If vehicle is not repaired or additional diagnostic information is not available, reprogram PCM if later calibration is available. Retest.