Surges/Chuggles

Definition
Engine power variation under throttle or cruise. Feels like the vehicle speeds up and slows down with no change in accelerator pedal position. Make sure the driver understands the operation of the Torque Converter Clutch (TCC).

Preliminary Checks
Perform visual checks as described in Visual/Physical Checks in this section.

Sensors
^ CHECK: Oxygen sensor (02S). The 02S should respond quickly to different throttle positions. If it does not, check the sensor for silicone or other contaminations from fuel, or use of improper RTV sealant. The sensor may have a white, powdery coating and result in a high but false signal voltage (rich exhaust indication). The ECM/PCM will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Also, watch for green glycol contamination or cracking.

Fuel System

Notice: To determine if the condition is caused by a rich or lean system, the vehicle should be driven at the speed of the complaint. Monitoring O2S voltage will help identify a problem.

Lean - Refer to "Diagnostic Aids" under Diagnostic Trouble Code 25.
Rich - Refer to "Diagnostic Aids" under Diagnostic Trouble Code 26.

^ CHECK: Fuel filter. Replace if dirty or plugged.
^ CHECK: Fuel pressure while condition exists.

Ignition System
^ CHECK:For proper ignition voltage output using J26792 or equivalent.
^ CHECK: Spark plugs. Remove spark plugs, check for wet plugs, cracks, wear, improper gap, burned electrodes, or heavy deposits. Repair or replace as necessary. Also, check condition of distributor cap, rotor and spark plug wires.
^ CHECK: Ignition timing. Refer to "Vehicle Emission Control Information" label.

Additional Checks
^ CHECK: ECM/PCM grounds for being clean, tight and in their proper location.
^ CHECK: Vacuum hoses for kinks or leaks.
^ CHECK: Generator output voltage. Repair if less than 12 or more than 16 volts.
^ CHECK:EGR - There should be no EGR at idle. (California Emissions only).