E 320 Sedan (210.065) V6-3.2L (112.941) (1999)
Idle Speed: Description and Operation
ME-SFI Idle Speed Control Function
B11/4
Coolant temperature sensor
B37
Accelerator pedal sensor
M16/1
EA/CC/ISC [EFP/TPM/LLR] actuator (other designation: M16/6 throttle valve actuator)
N3/10
ME-SFI control unit
Task
Controlling idle speed in the case of
-
different engine loads, e.g. power steering turned to full lock, engaging drive mode, switching on AC compressor
-
different mixture, e.g. from activated charcoal canister if purging activated (depending on activated charcoal charge)
Function
The actuator EFP/TPM/LLR (additional designation: throttle valve actuator) regulates the idling speed by changing the throttle valve position. It is
actuated by the ME-SFI control unit.
The ME-SFI control unit actuates the throttle valve motor (M16/1m1) in line with the input signals received at the ME-SFI control unit (N3/10).
Heating speed of the catalytic converter
In order to warm up the catalytic converter more rapidly to operating temperature, engine speed is increased in the idle speed range to 1100 up to 1500
rpm for about 20 seconds after each starting procedure at coolant temperatures of < 40 °C. When a Drive position is engaged, engine speed is
immediately controlled to a lower value.
Automatic transmission
When a drive position is engaged, a lower engine speed is controlled in order to reduce the creeping tendency of the vehicle. The information "Drive
position engaged/not engaged" is transmitted by the ETC control unit (N15/3) over the CAN databus to the ME-SFI control unit.
Ignition angle
To assist the idle speed control, the ignition angle can be retarded by as much as 36° crank angle or advanced by as much as 20° crank angle from the
calculated specified value.
Note: The control in the idle speed range by altering the ignition angle reacts more rapidly than altering the position of the throttle valve.