Rough, Unstable, or Incorrect Idle, Stalling
ROUGH, UNSTABLE OR INCORRECT IDLE, STALLINGDefinition:
The engine runs unevenly at idle. If bad enough, the vehicle 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.
Check:
^ Throttle linkage for sticking or binding
^ Throttle position sensor should read zero percent at idle on Scan tool.
^ IAC System.
^ Generator output voltage. Repair if less than 9 volts or more than 16 volts.
^ Injector Balance.
^ EVAP canister purge system
^ Minimum air rate
^ Catalytic converter blockage
^ Check Terminals and wires at Electronic Ignition (EI) module
^ Check Terminals and wires to crank position sensor
^ PCM power and grounds
^ Fuel pressure
^ Ignition system with Saturn Basic Engine Analyser (SBEA) tester.
^ Spark plugs and wires
^ Cylinder compression.
Monitor long term fuel trim values on scan tool if system is running lean (block learn near 190) (refer to Diagnostic Aids of DTC 45.) Testing and Inspection