500SE HIGH IDLE

I have a 1983 500se euro spec 180 000 miles.
I use this car for business and drive regularly acroos Europe.It is wonderfull!!

However,recently in order to prevent the engine stalling when it is put into drive the idle has had to be adjusted to run at about 1100 RPM when in park or neutral.
In drive the car then idles (at correct running temp.)at about 550RPM.
If the Air-Con is switched on the engine will stall at standstill in drive.

I have replaced ignition leads,distributer cap,rotor arm,plugs,air filter and although the engine now runs much smoother this problem has NOT gone away.

Also since this problem arose the car does not idle well and will sometimes shake and judder slightly in gear particularly when warm.

There is no oil useage and oil pressure is good.

Any help would be appreciated as this is spoiling an otherwise wonderfull car.

Thanks in advance.

[Benzmac]

How did you adjust the idle to 1100? I thought this modle had the electronic idle speed control...If so, you probably need the actuator and or the control unit...We carry them in the rebuilt unit and new.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

quote:

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Originally posted by Benzmac:
How did you adjust the idle to 1100? I thought this modle had the electronic idle speed control...If so, you probably need the actuator and or the control unit...We carry them in the rebuilt unit and new.

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JUST IN FRONT OF THE AIR CLEANER CASING IS A CREAM SPRING LOADED PLASTIC SCREW ABOUT AS WIDE AS BOTTLE TOP IT IS SLOTTED.TURNING THIS IN INCREASES THE IDLE SPEED.IS THIS THE CORRECT WAY TO ADJUST IDLE SPEED??

[Benzmac]

The problem you are having is the idle thermostat. You have a thermostat located near the screw you are talking about. The thermostat allows the car to idle high when cold and normally when warm...Have it checked.

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Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

quote:

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Originally posted by Benzmac:
The problem you are having is the idle thermostat. You have a thermostat located near the screw you are talking about. The thermostat allows the car to idle high when cold and normally when warm...Have it checked.

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WILL CHANGING THIS IDLE THERMOSTAT THEN ALLOW ME TO REDUCE THE IDLE IN PARK TO WHAT IT WAS I.E. ABOUT 700RPM??