Engine and Emission Control System Description - Idle Speed Control
EF & EC-21prose procedureIdle Speed Control
INPUT/OUTPUT SIGNAL LINE
Crank angle sensor
SignalEngine speed
Engine temperature sensor
SignalEngine coolant temperature
Ignition switch
SignalStart signal
Throttle sensor
SignalThrottle valve position / Throttle valve idle position
Neutral switch
SignalNeutral position
Air conditioner switch
SignalAir conditioner operation
Power steering oil pressure switch
SignalPower steering load signal
Battery
SignalBattery voltage
Vehicle speed sensor
SignalVehicle speed
Load switch (N-CVT)
SignalClutch signal
A.B.S.
SignalN.C.V.T. vehicles
SYSTEM DESCRIPTION
NOTE
This system automatically controls engine idle speed to a specified level. Idle speed is controlled through fine adjustment of the amount of air which by-passes the throttle valve via A.A.C. valve. The A.A.C. valve repeats ON/OFF operation according to the signal sent from the E.C.U. The crank angle sensor detects the actual engine speed and sends a signal to the E.C.U. The E.C.U. then controls the ON/OFF time of the A.A.C. valve so that engine speed coincides with the target value memorized in ROM. The target engine speed is the lowest speed at which the engine can operate steadily. The optimum value stored in the ROM is determined by taking into consideration various engine conditions, such as warming up and during deceleration, fuel consumption, and engine load (air conditioner, electrical load).