Can someone please tell me where it's located on a 1991 300E and how difficult is it to change?

Thanks
Nick

Pull off the air assembly and it is held in by two bolts near the front. Before changing it, remove it and clean out the insides with some carb cleaner. You won't believe how much gunk will come out.

It has two air hoses attached to each side. So just pop them off (if they are hard/cracked replace them now!)

If you are having idle problems, just cleaning it may drastically help/resolve it completely.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

Thanks ps2cho!

Yes I am having idle problems, especially with the car in gear and the A/C on. Almost feels like it wants to stall but smooths right out if I shift into neutral or turn off the A/C.

I will clean it out ASAP

Nick

Purpose of "idle control valve" is to provide extra air during cold starts.

Think it never functions once motor is warm.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

Here's a foto. Engine is M103 2.6 but is the same.
The IACV is the sliver coloured metal cylinder with the electrical terminal on the left in the middle of the frame. Two bolts and a hard rubber holder fixing it to the manifold.

Correct, but there is a chance it could be stuck open.
You may also want to check out all the OVP threads on stalling if you have not already.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

The OVP solved a stalling issue that plagued my gf's car for a long time. If the ICV isnt the issue then I would check that next, hers had some corrosion around the bottom which to me says water got in there some how. Replaced it and idle is back to normal again.

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88 300E
03 911 C4S
2008 Triumph Speed Triple

My pics --> www.BrettAdamsDesign.com

what I did with my 1990 300TE to fix a a hard starting (when warm), stalling and erratic idling problem was change the coolant temp sensor and change the spark plugs, it was about $75 all together..car has run great ever since, and that was last June I did this....been like a brand new car from that point forward. good luck

The idle control valve operates all the time - at least when your foot is off the gas. It opens a bit when you put the auto trans in gear. It opens a bit when the AC compressor comes on.

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2012 E350
2006 Callaway SC560

Hello all... I'm new member to the boards here, but I have been lurking since I got my 1990 300ce. Love the car, but it had a few "issues". I've had it about two weeks. It has many of the same symptoms/gremlins that have been talked about in these forums (hard start, rough cold idle, hesitation on acceleration, abs light appeared, exterior light comes on sometimes, safety belt motor arms not going back in place).

I got the car from a friend that took very good care of it and had kept all the records of repairs. She had thrown a lot of parts at it (plugs & wires, rotor, cap, vacuum lines, etc. etc.). She told me her mechanic recommended trying to swap out the idle control valve next. I did some research and the rough idle and hesitation looked like it was being caused by the ICV and I was getting ready to plunk $500 down for her mechanic to fix it. I'm glad I didn't.

After exploring these boards and reading the posts on OVP problems, I figured what could it hurt. I looked through the car records and a OVP replacement was not listed anywhere. I pulled it and replaced it (it was the original). I am glad I did. You guys saved me a $500 bill from the mechanic.

Installed the new OVP last night and it cranked on the first try this morning. Smoothed out the cold idle and it seems to be behaving much nicer.

Thanks again... You guys rock! This site was a great resource for someone that has never worked on a Mercedes before.

chicken, recommend disabling the seat belt presenters by pulling the fuse that controls their motors. Be sure to set the passenger side outside mirror fist because that same fuse disables that control too. With the seat belt presenter disabled simply reach back with your hand just above the floor for the seat belt. I own two 300CE's and have disabled the seat belt presenters on both.

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Fred Hoelzle

Why, may I ask?

R

That's why.

Yes, sorry, I see the point.

Is there any way of fixing it? You can get at the mechanism behind the trim panel.

Just a thought.

R