Surges and/or Chugs

DEFINITION:
Engine power variation under steady throttle or cruise. Feels like the car 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.

CHECK:

- For intermittent EGR at idle.
- Ignition timing. See Emission Control Information Label.
- Inline fuel filter for dirt or restriction.
- Fuel pressure.
- Generator output voltage. Repair, if less than 9 or more than 16 volts.

Inspect Oxygen sensor for silicone 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 ECU 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 the condition of the rest of the ignition system.