Idle Speed: Notes

Engine idle speed is controlled by ECM based on engine operating conditions and component/model application. ECM senses engine operating conditions and determines lowest speed engine will operate steadily. Basic idle speed is adjusted by changing amount of air by-passing throttle plate via Idle Air Control Valve-Auxiliary Air Control (IACV-AAC) Valve. More will flow through IACV-ACC valve the longer the ON duty signal is left on.

Fast idle required for cold starts is accomplished through use of an ECM-controlled Fast Idle Control Device (FICD) and air regulator (G20 and J30) or thermowax pellet Fast Idle Cam (FIC) (Q45).