380 SEL idle high when warm

My car is 82 380 SEL. lately its been giving me a headache. The idle on the car is perfect, rock steady when the engine is cold (around 700-1000 rpm). On park and neutral.

When it gets warm the idle would stays on 1500-1800 rpm on park and neutral. but when I put on the gear (D or R) it goes down to a 1000 rpm.

I rewett the solder joint on the idle control unit and clean the idle valve but no LUCK ! the idle still stays at 1500-1800 rpm when warm park and neutral. Replace the OVR or OVP, same thing no luck , idle still high.

Please help me. This car is my daily driver and I could not afford another car to get around since my other car 86 SAAB 9000 turbo Carlsson edition needs a fuel pump and sitting in my garage.

Insurance is expensive here in NY

[JohninFla]

Try checking the throttle position switch. It is a switch at the base of the throttle that tells the car to idle. It "makes" when your foot is off the accelerator and the linkage returns to the home position. You will find a 2 wire connector coming up from the base of the throttle housing. Disconnect it and check for continuity when the throttle is released, then check for open when the throttle moves. You will find a procedure for setting the proper linkage position in the CD Rom manual.

Best of luck!

Thanks for your reply,

Where exactly the switch is located, please bare with me as I am new to mercedes.
Is this part fixable or I have to get a new one if it defected ? is it DIY stuff ?


thank you.

[JohninFla]

The switch is at the base of the throttle housing. Remove the air cleaner housing. Look where the plate is that opens when you step on the gas, and lets air into the intake. I am not sure which side it is on your car, but look on either side. There is a pivot rod sort of thing that moves when you step on the gas pedal, and on the end of it is a switch. Sort of like a neutral start switch, only lots smaller. It is not repairable. Check it with an ohm meter to see if it works before you decide to replace it. I don't know if it is DIY. It is a piece of work to get to.