Possible Cause & Correction

Using a "SCAN" tool, ensure vehicle speed matches VSS reading. If tool is not available, or if readings do not agree, check:

• Intermittent EGR operation during idle condition. See EGR SYSTEM CHECK chart in the TBI TESTS/CODES article in this section.
• Ignition timing.
• In-line fuel filter for obstruction.
• Fuel pressure. See CHART A6 - FUEL SYSTEM PRESSURE TEST chart in the TBI TESTS/CODES article in this section.
• Alternator output. Repair if less than 9 volts or more than 16 volts.
• TCC operation. See TORQUE CONVERTER CLUTCH chart in the TBI TESTS/CODES article in this section.
• Inspect oxygen sensor for silicon contamination from fuel, or use of improper RTV sealant (sensor will have White, powdery coating that will result in high, but false, signal voltage). In return, the ECM will reduce amount of fuel delivered, causing a severe driveability problem.
• Remove spark plugs and check for cracks, wear, improper gap, burned electrodes, or heavy deposits. Check condition of distributor cap, rotor, and plug wires.