High Idle speed

[merc380sel]

My 1985 380sel idle speed when gear is on N or P is around the 1400 rpm. It sometimes reach 2000rpm in between gear shift,
giving the car a hard jerk when gear is engaged.
My mechanic yesterday clean the idle controller, replaced the leads and rotor and plugs.
The problems still persist and the engine misfire occationally and the idle was rough too. Could there be other problem that he might missed, like injectors, fuel dividers etc. I'm not a mechanic, so could any one help!

[Mervyn]

Try checking the ignition control module. You could try swapping your ignition control module for another one which is in good working condition, and if the problem is gone, then you know where the fault lies. My module has given me problems of intermittent stalls, and before I changed it, my idle RPM at N or P was around 1200-1300. My new module gives me 900.

And of course get your mechanic to adjust the timing too. Lastly, make sure your plugs are copper ones, not platinums. The latter gives some hesitation and stumbling especially during idle.

Good Luck!

Mervyn

[ymsin]

This may be of help:

From http://www.w126.com -

"Engine

The engines are known for their durability. If an engine is properly maintained, it can easily run for 300.000 - 400.000 kilometers without a rebuild. The V8 engines are alloy engines and the walls of the cylinder housings are coated with a silicium-based layer. Expect to change a distribution chain every 250.000 kilometers. The early Bosch K-jetronic continuous fuel injection systems can develop a rough idle over time. Typically, a V8 should run about 650 - 700 rpm at idle when hot. If the car will develop a jumpy idle (jumping from about 1500 rpm to 500 and up again), the electronic control module is likely to be at fault. Post-1985 models were equipped with Bosch KE-jetronic pulsed fuel injection systems with a completely electronic engine management system. "

Hope this will help you.

I had the same problem..my I replaced the idle control valve and the problem got worse..then I replaced the idle control relay and it has run like a new car.

the valve I got from e bay for 125 and the relay was about 250.00

good luck

benzat
1982 380 sec

[ymsin]

Benzat - where is the idle control relay located, and the part number if possible?

[Mervyn]

Yeah, I would also like to know about the idle control relay, although I got this feeling that W126's do not have it, or at least my 280SEL does not have it. After replacing my idle control valve 2 weeks ago, it has helped stabilise the low idle speed a little, although there're still little vibrations at idle, which I hope to eradicate somehow.

Anyone knows anything on this idle control relay on W126s?
Part number is greatly appreciated!
Mervyn

Repaired the electronic idle speed control unit on my w126 500se two weeks ago. For a helpful picture of the unit look at the parts catalogue in Fastlane.

The location of the unit varies from model to model but in the RHD 500se the unit is situated above the steering shaft and behind the instrument cluster. It is held in place by a self tapping screw which is well nigh impossible to remove without a flexible screwdriver. Once removed it is best to replace with a suitable cable tie.

Faults on the electronic unit are generally dry joints which can be easily picked out using a magnifying glass or other magnifying viewer. Simple repair with a soldering iron.

mine is located on the firewall about in the middle

the part number I have is 002 545 01 32.for the idle control relay.

mine is located on the firewall about in the middle

the part number I have is 002 545 01 32.for the idle control relay


benzat 1982 380 SEC

[geoellis]

Just a thought. I'm not a mechanic either, but I had a high idle problem once on a non-Benz car that was caused by a vacuum leak in the fuel injection system.

Good luck.