How to adjust idle speed on '87 300D? - PeachParts Mercedes-Benz Forum

Diesel Dan · #1 02-12-2008, 09:49 PM

I've searched the archives, but not found anything tangeable enough to help me. My idle speed varies from 500rpm - 650rpm, which is a bit low for my taste. I'd like to bump it up about 100rpm. Can someone tell me where I can find the idle adjustment for my car?

Thanks!

babymog · #2 02-12-2008, 10:34 PM

There is a round plug just inboard of the fusebox under the hood, looks like a knob with numbers on it. Unplug it and index it up one number.

Does the tachometer work?

#3 02-12-2008, 10:56 PM

Sounds like you have a loose connection. Make sure the plug on the injection pump is firmly plugged in.

Diesel Dan · #4 03-07-2008, 01:18 PM

Quote:

Originally Posted by babymog

There is a round plug just inboard of the fusebox under the hood, looks like a knob with numbers on it. Unplug it and index it up one number.

Does the tachometer work?

The tachometer has been intermittantly not working. This will occur upon startup and lasts for a couple minutes. I will start the car, and the idle will be extraordinarily low, with the tachometer not responding at all. At some point there will be a slight surge in the idle, with a corresponding reaction of the tachometer, and then the engine returns to normal idle, and the tachometer is working again.

Anyone have ideas of what is going on here?

babymog · #5 03-07-2008, 01:57 PM

If the ABS warning light works, and stays on while the tach in in-op, search Overvoltage Protection Relay. If not, sounds like the crank position sensor.

joro · #6 03-08-2008, 01:35 AM

Wont turning up the alda also adjust iddle on w124?

#7 03-08-2008, 04:03 AM

Quote:

Originally Posted by joro

Wont turning up the alda also adjust iddle on w124?

No, the idle computer will automatically compensate for it.