Rough, Unstable, or Incorrect Idle, Stalling

Definition: The engine runs unevenly at idle. If bad enough, the car may shake. Also, the idle may vary in RPM (called "hunting"). Either condition may be bad enough to cause stalling. Engine idles at incorrect speed.

^ Perform careful visual check.

^ Check throttle linkage for sticking or binding.

^ Check ignition timing. See Emission Control Information label.

^ Check IAC system. See CHART C-2C. Chart C-2B Idle Air Control (IAC) Valve Check

^ Check generator output voltage Repair if less than 9 or more than 16 volts.

^ Check P/N switch circuit. See CHART C-1A. Chart C-1A Park/Neutral Switch Diagnosis

^ Check injector balance. See CHART C-2A. Chart C-2A Injector Balance Test

^ If ROUGH IDLE only occurs HOT, perform these additional checks:

^ Check PCV valve for proper operation by placing finger over inlet hole in valve end several times. Valve should snap back. If not, replace valve.

^ Check Evaporative Emission Control System. CHART C-3. Chart C-3 Canister Purge Check

^ Run a cylinder compression check.

^ Inspect Oxygen sensor for silicon contamination from fuel, or use of improper RTV sealant. The sensor will have a white, powdery coating, and will result in a high but false signal voltage (rich exhaust indication). The Engine Control Module (ECM) will then reduce the amount of fuel delivered to the engine, causing a severe driveability problem.

^ Check for fuel in pressure regulator hose. If present replace regulator assembly (port).

^ With Air Management Systems check for intermittent Air to Ports while in closed loop.