Symptom Definition

Engine delivers less power than expected. Little or no increase in speed when accelerator is pushed down.

Possible Cause & Correction Check the following:

• Check air filter and fuel filter. Replace if necessary. Check for incorrect fuel pressure.
• Check injector wires for short to ground at air cleaner.
• Check for proper operation of thermostatic air cleaner damper door.
• Ensure initial ignition timing is properly set.
• Check for proper operation of TCC system.
• Check ECM grounds.
• Check ESC system for excessive retard.
• Check EST system for proper operation.
• Ensure EGR valve is not always open.
• Check exhaust system for restrictions, such as a damaged or collapsed pipe, muffler or catalytic converter. See BASIC TESTING article.
• Check charging system output. Repair charging system if voltage is less than 9 volts or more than 16 volts.
• Check MAP sensor output.
• Using Spark Tester (ST-125), check for available secondary voltage.
• Check engine valve timing and compression.
• Check engine for a worn camshaft.