For 1990-2009 cars

Checks | Action
--- | ---
DEFINITION: Engine delivers less than expected power. Little or no increase in speed when the accelerator pedal is pushed down part way.
Preliminary Checks |

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

• | Refer to Visual/Physical Checks .

• | Search for bulletins.

Fuel System |

• | Check for incorrect fuel pressure.

- | Refer to Fuel System Pressure Test (VIN K) .

- | Refer to Fuel System Pressure Test (VIN 1) .

• | Check the fuel injectors.

- | Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) .

- | Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F) .

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

• | Check items which can cause an engine to run rich (long term fuel trim is significantly in the negative range). Refer to Diagnostic Aids for DTC P0172 Fuel Trim System Rich .

• | Check items that can cause an engine to run lean (long term fuel trim is significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 Fuel Trim System Lean .

Sensor/System |

• | Using a scan tool, monitor KS system for excessive spark retard activity.

• | Check the EGR valve for a stuck open pintle. Refer to Exhaust Gas Recirculation Valve Replacement .

• | Check for a restricted intake duct or a dirty air cleaner element. Refer to Air Cleaner Element Replacement .

• | (VIN 1 only) -- Check for proper supercharger boost control operation. Refer to Boost Control System Diagnosis .

Ignition System |

• | Check for proper ignition voltage output using the following steps:

- | Clip the spark tester J 26792 to engine ground.

- | Connect one end of a spark plug wire to the spark tester; leave the other end of the spark plug wire to the coil being tested.

- | Connect one end of another spark plug wire to the other coil tower; connect the other end of the spark plug wire to ground.

- | Crank the engine while observing the spark tester; a crisp blue spark should be observed.

- | Repeat the above steps for each coil.

• | If adequate spark is not present at the coils, check for the following conditions:

- | Coils - Cracks, carbon tracking/arcing, or a resistance value outside the specified range.

Coil Secondary Resistance
5000 - 8000 ohms (5K - 8K ohms)

- | Spark Plug wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, incorrect routing, or a resistance value greater than the specified value.

VIN 1 Spark Plug Wires Resistance
3280 - 4921 ohms per meter (1000 - 1500 ohms per foot).

VIN K Spark Plug Wires Resistance
3280 - 4921 ohms per meter (1000 - 1500 ohms per foot).

| Important: Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition components will arc to ground when a secondary component is malfunctioning.

- | Malfunctioning ignition control module.

- | Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.

• | Remove spark plugs and check for the following conditions:

- | Fouled plugs

- | Cracks

- | Wear

- | Incorrect gap

- | Burned or damaged electrodes

- | Incorrect heat range

• | If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

Engine Mechanical |

• | Excessive oil in combustion chamber - Leaking valve seals. Refer to Oil Consumption Diagnosis .

• | Low cylinder compression. Refer to Engine Compression Test .

• | For incorrect basic engine parts. Inspect the following:

- | Camshaft

- | Cylinder heads

- | Pistons, etc.

Additional Checks |

• | Check the exhaust system for a possible restriction.

• | Inspect the exhaust system for damaged or collapsed pipes.

• | Inspect the muffler for heat distress or possible internal failure.

• | Check for a plugged three-way catalytic converter. Refer to Restricted Exhaust System Check .

• | Check for proper TCC operation. Refer to Torque Converter Clutch Evaluation and Diagnosis .