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

    • Refer to Symptoms .
    • Make sure the customer has an actual problem.
    • Check the fuel quality.

Fuel System Checks

    • Check the injection pump.
    • Check the injection pump timing. Refer to Fuel Injection Pump Timing Adjustment .
    • Check the injection nozzles. Refer to Injection Nozzle(s) Diagnosis .

Sensor Check

    • Check the engine coolant temperature (ECT) sensor. Use 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.
    • Check the glow plug system operation. Refer to Glow Plug System Check .

Air Intake System Check

    • Check the air cleaner and the air intake ducts for restriction.
    • Check for a restriction in the turbocharger inlet duct.
    • Check for a restriction in the intake manifold.

Engine Mechanical Check

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