Rough, Unstable Idle
- Check throttle linkage for sticking. Check idle speed. Check IAC system. See IDLE AIR CONTROL TEST chart in the appropriate PFI TESTS W/ CODES article. Check alternator output voltage. Voltage should range from 9-16 volts. If voltage is outside range, repair as necessary.
- Check injector balance. See INJECTOR BALANCE TEST chart. Check EGR system. There should be no EGR at idle. Check fuel pressure regulator operation. See FUEL SYSTEM DIAGNOSIS in the appropriate PFI TESTS W/ CODES article. Check ignition system.
- Disconnect MAF sensor. If condition persists, replace sensor. Check park or neutral and power steering pressure switches for proper operation. On all engines, inspect O2 sensor for silicon contamination from fuel or improper use of RTV sealant. Sensor is defective if it is coated with a White, powdery coating.