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 [AJ] DIAGNOSTIC PROCEDURE

STEP	INSPECTION		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 rings are 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 Engine block cracks or porosity 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 okay?	Yes	Go to the next step.
4		No	Service as necessary. Repeat Step 4.
5	Connect WDS or equivalent to DLC-2. Turn ignition switch to ON position. Retrieve any DTC. Are there any DTCs displayed?	Yes	DTC displayed: Go to appropriate DTC test.
5		No	No DTC displayed: Go to the next step.
6	Install fuel pressure gauge between fuel filter and fuel distributor. Start engine and run it at idle. Measure fuel line pressure at idle. (See FUEL LINE PRESSURE INSPECTION .) Is fuel line pressure correct at idle?	Yes	Go to the next step.
6		No	Zero or low: Inspect fuel pump relay and fuel pump circuit. Inspect for clogged fuel line. If okay, replace fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .) High: Replace fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION .)
7	Perform spark test. (See SPARK TEST .) Is strong blue spark visible at each cylinder?	Yes	Inspect spark plugs and CMP sensor. (See CAMSHAFT POSITION (CMP) SENSOR INSPECTION .)
7		No	Repair or replace malfunctioning part according to results of spark test.
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.