GM Service Manual Online
For 1990-2009 cars only

Checks

Action

Definition: White, black, gray or blue smoke under load, idle or start up hot or cold.

Preliminary Check

    â€¢ Refer to Symptoms .
    â€¢ Make sure the vehicle has an actual problem.
    â€¢ Check the fuel quality. Refer to Contamination Testing .

Fuel System Checks

    â€¢ Check the injection pump. Refer to Fuel Supply System Check .
    â€¢ Check the injection pump timing. Refer to Fuel Injection Pump Timing Adjustment .
    â€¢ Check the injection nozzles. Refer to Injection Nozzle(s) Diagnosis .

Sensor Check

    â€¢ Check the Engine Coolant Temperature (ECT) sensor by using the Scan Tool in order to compare the engine coolant temperature with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 5° greater or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit or the sensor itself.
    â€¢ Check the glow plug system operation.

Air Intake System Check

    â€¢ Check the air cleaner and the air intake ducts for a restriction.
    â€¢ Check for a restriction in the turbo charger inlet duct.
    â€¢ Check for a restriction in the intake manifold.

Engine Mechanical Check

    â€¢ Check for incorrect basic engine parts such as the cam, the heads, the pistons, etc.
    â€¢ Check for any excessive oil entering the combustion chamber.