Lack of Power/Sluggish/Spongy/Stumble

Definition: Engine delivers less than expected power. Little or no increase in speed when accelerator pedal is pushed down part way.



PRELIMINARY CHECKS

^ Perform the careful visual/physical checks as described in "Preliminary Checks."
^ Compare customer's vehicle to similar unit. Make sure the customer has an actual problem.
^ Remove air filter and check air filter for dirt, or for being plugged. Replace as necessary.

IGNITION SYSTEM

^ CHECK: Knock Sensor (KS) system for excessive spark retard activity. Refer to CHART C-5. Chart C-5 Knock Sensor (KS) System Check
^ CHECK: Secondary voltage using a spark tester J 26792 (ST-i 25) or equivalent to check for a weak coil.
^ CHECK: Spark advance for excessive retarded ignition timing. Refer to CHART C-5. Chart C-5 Knock Sensor (KS) System Check

ENGINE MECHANICAL

^ CHECK: Engine valve timing and compression.
^ CHECK: Engine for correct or worn camshaft.

FUEL SYSTEM

^ CHECK: Restricted fuel filter.
^ CHECK: Fuel pressure, use CHART A-7. Related Tests, Information and Procedures
^ CHECK: Contaminated fuel.

ADDITIONAL CHECKS

^ CHECK: PCM grounds for being clean, tight and in their proper locations. See PCM wiring diagrams.
^ CHECK: Torque Converter Clutch (TCC) for proper operation.
^ CHECK: Generator output voltage. Repair if less than 9 or more than 16 volts.
^ CHECK: A/C operation. A/C clutch should cut out at Wide Open Throttle (WOT). Refer to CHART C-10. Chart C-10 A/C Clutch Control Circuit Diagnosis
^ CHECK: Exhaust system for possible restriction. Refer to CHART B-1.
- Inspect exhaust system for damaged or collapsed pipes.
- Inspect muffler for heat distress.
- For possible plugged three-way converter.