Lack of Power/Sluggish/Spongy/Stumble

DEFINITION
The engine delivers less than expected power. Little or no increase in speed when the accelerator pedal is pushed down part way.

PRELIMINARY INSPECTION
^ Perform the careful "Visual And Physical Checks" in Preliminary Checks. Testing and Inspection
^ Compare customer's vehicle to similar vehicle. Verify symptom.
^ Remove air filter and check air filter for dirt, or for being plugged. Replace as necessary.

FUEL SYSTEM
^ CHECK: Fuel pressure. Refer to Fuel System Pressure Test.
^ CHECK: Restricted fuel filter.
^ CHECK: Contaminated fuel.

IGNITION SYSTEM
^ CHECK: Ignition timing. Refer to Ignition Timing Adjustment. Ignition Timing
^ CHECK: Secondary voltage using J26792 or equivalent, to check for a faulty ignition coil.

ADDITIONAL CHECKS
^ CHECK: ECM grounds for being clean, tight and in their proper locations. See ECM wiring diagrams.
^ CHECK: Generator output voltage. Repair if less than 12 or more than 16 volts.
^ CHECK: A/C operation. A/C compressor clutch should cut out at Wide Open Throttle (WOT).
^ CHECK: Exhaust system for possible restriction.
- Inspect exhaust system for damaged or collapsed pipes.
- Inspect muffler for heat distress or possible internal failure.
- For possible plugged catalytic converter.
^ CHECK: Torque Converter Clutch (TCC) for proper operation.
^ CHECK: EGR operation for being open or partly open all the time (If equipped).

ENGINE MECHANICAL
^ CHECK: Engine valve timing and compression.