For 1990-2009 cars

#### Surges/Chuggles

Checks | Action
--- | ---
DEFINITION: Engine power variation under steady throttle or cruise. Feels like the vehicle speeds up and slows down with no change in the accelerator pedal.
Preliminary |

• | Refer to Diagnostic System Check - Engine Controls .

• | Refer to Symptoms - Engine Controls .

• | Search for service bulletins.

• | Be sure the driver understands the transmission torque converter clutch (TCC), and the A/C compressor operation as explained in the owners manual. Inform the customer how the TCC and the A/C clutch operates.

• | Check the powertrain control module (PCM) grounds for the following conditions:

- | Clean connection

- | Tight connection

- | Proper location

Sensor/System |

• | Check the oxygen sensor (O2S 1). The O2S 1 should respond quickly to different throttle positions. If not, check the O2S 1 for silicon or other contaminants from fuel or the use of improper RTV sealant. The sensor may have a white powdery coating. Silicon contamination causes a high but false O2S 1 signal voltage, rich exhaust indication. The powertrain control module (PCM) will reduce the amount of fuel delivered to the engine, causing a severe driveability problem.

• | Check for proper operation of the manifold absolute pressure (MAP) sensor. Refer to DTC P0105 .

• | Check for proper operation of the throttle position (TP) sensor. Refer to DTC P0105 .

• | Check for proper operation of the engine coolant temperature (ECT) sensor. Refer to DTC P0117 and DTC P0118 .

Fuel System |

• | Check the fuel pressure. Refer to Fuel System Diagnosis .

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

• | Check the fuel filter for being plugged or restricted.

• | Ensure each fuel injector harness is connected to the correct fuel injector/cylinder. Refer to Engine Controls Schematics .

• | Check items which can cause an engine to run rich, long term FT is significantly in the negative range. Refer to Diagnostic Aids for DTC P0172 .

• | Check items that can cause an engine to run lean, long term FT is significantly in the positive range. Refer to Diagnostic Aids for DTC P0171 .

Ignition System |

• | Check for proper ignition voltage output with the J 36012-A Ignition System Diagnostic Harness and J 26792 Spark Tester or equivalent.

• | Check the spark plugs for the following conditions:

- | Check for wet or fuel fouled spark plugs.

- | Check for cracks on the spark plugs.

- | Check for wear.

- | Check for improper spark plug gap.

- | Check for burned electrodes or heavy deposits.

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

• | Check the ignition control module (ICM) for proper ground connection.

• | Check the ignition coils for cracks or carbon tracking.

Additional Checks |

• | Check for proper operation of the TCC. Refer to Road Test in Automatic Transmission 4T40-E/4T45-E .

• | Check the exhaust system for a possible restriction:

- | Inspect the exhaust system for damaged or for possible collapsed pipes.

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

- | Check for possible plugged three-way catalytic converter. Refer to Restricted Exhaust in Engine Exhaust.

• | Check the vacuum lines for kinks or leaks.

• | Check the generator output voltage. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical.

• | If all procedures have been completed and no malfunctions have not been found, review and inspect the following items:

- | Visually and physically inspect all electrical connections within the suspected circuit and/or systems.

- | Check scan tool data. Refer to Scan Tool Data List .