For 1990-2009 cars

Checks | Action
--- | ---
DEFINITION: The engine delivers less than expected power. There is little or no increase in speed when partially applying the accelerator pedal.
Preliminary Checks |

• | Refer to Powertrain On Board Diagnostic (OBD) System Check .

• | Refer to Symptoms .

• | Compare the customer vehicle with a similar vehicle in order to determine the severity of the customer concern.

• | Remove the air filter element and check for dirt or restrictions.

• | Check the transmission shift pattern and down shift operation.

Fuel System Checks |

• | Check for a restriction in the fuel supply system. Check for the correct fuel pressure. Refer to Fuel System Diagnosis .

• | Check the fuel injectors. Perform the Fuel Injector Coil Test Procedure and the Fuel Injector Balance Test Procedure. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) and to Fuel Injector Balance Test .

• | Check for contaminated fuel or inferior quality fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System Checks |

• | Check for adequate secondary ignition voltage with a J 26792 spark tester or an equivalent.

• | Check for the correct ignition timing. Refer to Ignition Timing Adjustment .

• | Check for the proper operation of the ignition control system.

• | Check the camshaft position (CMP) sensor engine reference signal with a scan tool. Observe the Engine Speed parameter while operating the engine at the speed of the concern. The scan tool should indicate steady and linear RPM readings while running. If the erratic values, such as sudden spikes or drops in engine speed are displayed, the engine reference signal is not stable enough for the engine to run properly. Inspect the CMP sensor signal rotor and housing for worn bushings or drive coupling. Inspect for electromagnetic interference (EMI) of the reference signal.

Exhaust System Checks |

• | Check the exhaust system for a possible restriction. Refer to Restricted Exhaust System Check .

• | Inspect the exhaust system for damaged or collapsed pipes. Inspect the muffler for heat distress or an internal failure.

Additional Checks |

• | Verify the PCM grounds are clean, tight, and in the proper locations.

• | Check the generator output voltage.

Engine Mechanical Check | Check for any of the following engine mechanical problems:

• | A low compression

• | An incorrect valve timing

• | An incorrect or worn camshaft

Refer to Engine Compression Test in Engine Mechanical.