She starts up rough, but after about a minute she runs pretty good. The big problem is that most of the time she idles about 1800 rpms. A Mechanic recommedned replacing the idle box, but at over $200 for it, I was hoping I could fix it cheaper as it's my 16 yr old son's first car. Any ideas?

First check the connector thats underneath the box. They are known to wiggle loose. Several people have also said you can try to resolder the connections within the box.

Has the mechanic ruled out the idle valve itself, or other electrical problems?

__________________
1985 380SE Blue/Blue - 230,000 miles
2012 Subaru Forester 5-speed
2005 Toyota Sienna
2004 Chrysler Sebring convertible
1999 Toyota Tacoma

No, He hasn't. I was hoping to try the cheapest fix first and work my way up. I will take a look at the connections below the box and see if I can find anything needing repair. I also read that someone used 'electrowash' or something to that effect to clean the connections. I am still trying to identify that and try it also.

yup, I have idle problems also.


-First thing to check is the ICU. Pops right out, check for cold solder joints, clean contacts (I used caig deoxit, which you can get at radioshack) and put some die-electic grease on the contacts.

-This helped a little, but I still have problems. Next I pulled the "Air slide valve" and cleaned it (holding it with the contacts up, as to not get any cleaner on the coil inside) Cleaned with brake cleaner (Sprayed it until cleaner came out clear, not black) and lubed with ATF (atf wont ruin the coils) I also noticed that the tubing connecting the valve was loose on the valve, a couple of hose clamps took care of that.

..and I STILL have idle problems

__________________
-1983 VW Rabbit LS Diesel (5speed, VNT/Giles build)

Wow, it must be a common problem on these cars. I also have a 1985 380SE and it has a little problem.

When first started, it starts fine, but if it is cold out when you first start it and press the gas a little, when it idles back down- it idles low and goes back up until it warms up. I always let it warm up before taking off, but when I first accelerate on the road, it acts like it wants to stumble, then it clears out and does not do it again. It also always sounds like I have a slight miss (splutter from the exhaust) when idling, but the engine does not shake. Not sure about this. ???

Then, after it is warm and I restart and place in gear- I have that stalling out problem that sometimes occurs. Sometimes too when I am idling at a stoplight, it will have a sporadic stumble, as if it wants to stall. One time I made a quick stop at a light and it stalled when it geared back into first. As far as my idle goes, it seems OK, around 600 when in drive and about 750 in park, but there have been times I noticed it is near 1000 rpms when in park, but not always.

I am wondering if all of this may not be my problem too. I suppose I should take it to one of our local MB shops and have it checked.

Good luck to you!

Our W126 SEL has been in the family for 12 yrs now let me just tell you these idle problems come back every 2 yrs on average.

I had enough of the thing...nothing beats an MB from the 90s.

__________________
99 C43
98 S420
99 C230K
01 C240

I'm experiencing this same exact problem.


I've done a few searches on it, it looks as if the fuel injectors/injector seal maybe to blame.

__________________
-1983 VW Rabbit LS Diesel (5speed, VNT/Giles build)

I experienced the same problem years back on an 85 380 SE and was able to clean the idle control valve with WD40 to eliminate symptons. Shortly after, I had a valve job done and mentioned the symptoms to my A+ indie. He installed a very small piece of tubing between the two hoses on the ICV sort of like a jumper. A few years later I noticed this jumper was stock on an 87 SEL. Maybe one of resident guru's is up to snuff on this remedy?

__________________
65 190d sold
85 380SE sold
87 560 SL 180K
84 380SE 96K (mint)

can you provide pics?

__________________
-1983 VW Rabbit LS Diesel (5speed, VNT/Giles build)

Yeah, sounds like we have the same problem. I too would like to know the exact location of this idle control valve and how to remove. I have been told several different things....

MONOMER - does your car also stall out sometimes when you place it in gear after it is warmed up? Mine does.

Location on my 380SE is right next to distributor on left with part of it covered by the air cleaner. Its a silver tube like part, with two short hoses attached along with a plug connection. Look in Fastlane under Fuel injection and you will see Idle control valve..about a $200.00 part so cleaning it first would be my first step. Cold start valve could also be a culprit. To check disconnect it and have someone start the cold engine. Fuel should squirt out if it is working properly.

__________________
95 E420 ( 76K) SOLD
85 380SE(125k)
95 SL500(72k)

"cold start valve"?


-I didnt have to much roadtime with this car yet (mainly due to the brakes not working) so I dont know.

the ICV/airslidevalve is in the front of the engine, right ontop/near the thermostat housing. Hoses connected to mine seemed loose, which I fixed with a couple of hose-clamps.

__________________
-1983 VW Rabbit LS Diesel (5speed, VNT/Giles build)

Lint to ICV at fastlane with pic:
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1Q1172JL21Q216YDXW&year=1985&make=MB&model=380-SE-001&category=C&part=Idle+Control+Valve

The hoses on each end can be bought pretty cheap. Try:
http://www.mercedes-benz-parts-direct.com/

The jumper hose I referred to goes between the two hoses on each end of the ICV sort of like a bypass. Didn't have it on my 85 380SE. Indie added it by drilling into 2 hoses at each end of ICV. Improved idle. Last time I looked at a V8 (87 420 SEL) this bypass hose looked like it had become a factory stock item. If you look at the photos of the hoses for the ICV for an 87 420 SEL at:
http://www.mercedes-benz-parts-direct.com/
you can see the jumper (hose connector) and a photo of the two ICV hoses with a place for this jumper to plug in. I don't recall seeing this arranagement on pre-87 V8s. Its possible the 87 ICV hoses and jumper will give you the mod on earlier V8s. Was hoping one of our resident gurus would have popped in by now. I am not an expert on this. Just passing on what I have seen.

__________________
65 190d sold
85 380SE sold
87 560 SL 180K
84 380SE 96K (mint)

you think drilling the two hoses and putting a peice of (generic) tubing in will work?

__________________
-1983 VW Rabbit LS Diesel (5speed, VNT/Giles build)

to fill us in on this one. Seems like my indie (as good a mercedes tech I've ever met, spent many years as a master at the local dealer) used what looked like a HVAC vaccum line (small diamieter) for the mod and he knew right where to tap into the hoses for what looked like a small bypass for the ICV. Like I said if you look at a 87 or later V8 I think you will see this already done by the factory. What we need is a pic from someone who has the ICV with the small bypass tubing installed from the factory and one of our resident expert's take on the subject. Don't go drillin on no mercedes based on my say!

__________________
65 190d sold
85 380SE sold
87 560 SL 180K
84 380SE 96K (mint)