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
1. Perform careful visual and physical checks as described in preliminary checks. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnosis by Symptom / Preliminary Checks. Testing and Inspection
2. Compare customer's vehicle to similar unit. Make sure the customer has an actual problem.
3. Remove air filter and check air filter for dirt, or for being plugged. Replace as necessary.

ADDITIONAL CHECKS
1. Check the Powertrain Control Module (PCM) grounds for being clean, tight and in their proper locations. Refer to PCM wiring diagrams.
2. Check the Exhaust Gas Recirculation (EGR) operation. The EGR valve may be open or partly open all the time. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart C-7. Chart C-7 EGR System Check
3. Check the generator output voltage. Repair if less than 9 volts or more than 16 volts.
4. Check the exhaust system for possible restriction. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart B-1. B Charts
^ Inspect exhaust system for damaged or collapsed pipes.
^ Inspect muffler for heat distress or possible internal failure.
5. Check the [1][2]Torque Converter Clutch (TCC) for proper operation.

ENGINE MECHANICAL
1. Check the engine valve timing and compression.
2. Check the engine for correct or worn camshaft.

IGNITION SYSTEM
1. Check the Knock Sensor (KS) system for excessive spark retard activity. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart C-5. Chart C-5 Knock Sensor (KS) System Check
2. Check Secondary voltage using a shop oscilloscope or a spark tester J 26792 (ST-125), or equivalent.

FUEL SYSTEM
1. Check for a restricted fuel filter.
2. Check the fuel pressure. Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart A-7. Related Tests, Information and Procedures
3. Check for contaminated fuel.
4. Perform the "Injector Coil / Balance Test." Refer to Computers and Controls / System Diagnosis / Procedures / Diagnostic Charts / Chart C2-A. Chart C-2A Fuel Injector Balance Test