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 (M16/1 m1) 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 o
f
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.
The control in the idle speed range by altering the ignition angle reacts more rapidly than altering the position o
f
the throttle valve.
The idling speed can be influenced with HHT or the STAR DIAGNOSIS.
AC compressor
In order to avoid engine speed dropping in the idle speed range when the AC compressor is engaged, the AC
push-button control unit (N19) or automatic air conditioning push-button control unit (N22) supplies a signal to
the ME-SFI control unit (as of approx. 6/96 over CAN) and the opening cross-section of the throttle valve is
enlarged.
When the air conditionin
g unit is switched on and the external temperature exceeds 35° C the idling speed on
2001 Mercedes-Benz ML320
1998-2005 ACCESSORIES & BODY CAB Throttle Control, Speed Control Systems - 163 Chassis
me
Saturday, October 02, 2010 3:36:27 PMPage 17 © 2006 Mitchell Repair Information Company, LLC.
