[2000CAYukon]

This is out of a 90 FSM. Hope it helps:


SURGES AND/OR CHUGGLE
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.

Use a "Scan" tool to make sure reading of VSS matches vehicle speedometer. See Code 24 in SECTION 3.
CHECK:
- For intermittent EGR at idle. See SECTION 9.
- Ignition timing. See "Vehicle Emission Control Information" label.
- Inline fuel filter for dirt or restriction. See CHART A-6 in SECTION 3.
- Fuel pressure. See CHART A-6 in SECTION 3.
- Generator output voltage. Repair, if less than 9 volts or more than 16 volts.
- TCC Operation. See SECTION 10.
Inspect Oxygen sensor for silicon contamination 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 will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem.
Remove spark plugs. Check for cracks, wear, improper gap, burned electrodes, or heavy deposits. Also, check condition of distributor cap, rotor, and spark plug wires.

//2000CAYukon