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 CHECKS
- Knock Sensor (KS) system for excessive spark retard activity. Refer to Chart C-5. Testing and Inspection
- Secondary voltage using a spark tester J 26792 (ST 125), or equivalent, to check for a weak coil.
- Spark advance for excessive retarded ignition timing. Refer to Chart C-5. Testing and Inspection

ENGINE MECHANICAL CHECKS
- Engine valve timing and compression.
- Engine for correct or worn camshaft.

FUEL SYSTEM CHECKS
- Restricted fuel filter.
- Fuel pressure, Use Chart A-7. Testing and Inspection
- Contaminated fuel.

ADDITIONAL CHECKS
- Powertrain Control Module (PCM) grounds for being clean, tight and in their proper locations.
- Torque Converter Clutch for proper operation. Transmission Control Systems
- Generator output voltage. Repair if less than 9 or more than 16 volts.
- 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 three-way converter.