ushawk1

My 1984 380 SE is idling crazy. I am having trouble pinning down a cause. Here is what is happening:
engine cold: ~800-1000 RPM in P/N and ~600 in gear.
engine at normal temp (around 80 degrees): ~2000 RPM in P/N, and ~1200 in gear.
engine really hot, (water temp 100+ degrees): ~800 RPM in P/N, and ~600 in gear.
It only gets really hot in heavy traffic with AC on, which is rare where I live. I can't stop anywhere, because putting your car in gear at 2000 RPM is like a clutch drop. You hear everything go CLUNK. I know it is not good for the trans. So if I stop, I am there til the car cools down. Even then, when the engine is cool, and it is warm outside, the engine will might idle high. I have done the tests per Chilton manual, and nothing changes. I suspect one of the temp switches, but am not sure. The tests didn't point in any direction, so probably have multiple things broke. Chilton's sucks for my car, and I have ordered the Mercedes maintenance CD's. Anybody else ever have this idle problem? What about an O2 sensor issue? I am almost going to cry because this is making me insane.

Somebody fabricate me an intake manifold so I can put a carb on this thing. Damn Bosch K systems are all or nothing.

w123_w126

The idle control valve may be stuck open. Remove it and soak in brake cleaner for a day or two. If that does not help it will need to be replaced.

ushawk1

I will try that. I hate having to replace it, because I could spend that few hundred bucks on something else like tires. There is no telling, because this car sat for a year before I got it. It was hardly ran during that time.

w123_w126

All the more reason to assume the valve is bad – I hope the soaking works; I had to replace mine – I don’t remember how much I paid for the valve – but the idle stayed at 550 after that.

bcmbcmbcm

where is this valve? Is it hard to replace? I have replaced this valve on other cars but never a MBZ

Thanks!

w123_w126

In the yellow:

ushawk1

I cleaned it out with some brake clean, and the inside looked like varnished gas. It idles better, still a little high, but not as erratic. I think replacement is going to be the next step. I thought about taking it apart. I have seen some on eBay for $230, and think MB dealer said $370.

w123_w126

Try some of the online parts stores like Autohaus AZ, Fastlane, and Rusty’s.

bcmbcmbcm

and no sales tax

bcmbcmbcm

I replaced this valve on my Mustang and it worked wonders.....cost $100 for that car though

Chi500

Do you guys know how I can take out this valve?

bcmbcmbcm

You will have to remove the air cleaner for better access, but look around at how it is held down and unbolt the old, replace the new.

It turns out that replacing this valve cured my Mustang of its idle woes, and replacing the ignition control box cured the Mercedes.

Chi500

Thanks. Is info on how to do this available anywhere online? I checked http://mb.braingears.com/ but it doesn't tell you how to do this. Where can I find the ignition control box?

bcmbcmbcm

under the hood, you are looking right at it. The factory box is a silvery color and rather big. Aftermarket boxes are smaller and usually black. I have been told that if you change the ignition box you should change the coil as well for good measure since a failing box can damage the coil.

Chi500

After I remove the bolt and the latch that holds the idle control valve down, do I just pull it out? thanks.

cruiser

An older post with good advice and photos. I recently replaced the ICB and it seemed to help but got the high idle problem again yesterday. I will try the ICV next. Thanks.

cruiser

FYI I replaced the valve and this did not help. Yesterday I replaced the idle control unit and that fixed the problem. I have my old car back. Now if we can just get to the source of those other little nuisances....