[W126 Coupe] Fast Idle Issue 1983 380SEC

[Mike R.]

I've seen a couple of IC Valves that are intermittent. There is a pair of wires that travel from the two pins on the ICV that go about 1/2" inside the ICV to the relay coil. They break. Mine was intermittent because the ends of the wire would touch, the ICV would work, then a bump would move them just far enough apart so that ICV would not work and the idle jumps to 1500. 
 
With the engine running, tap the ICV with a plastic hammer (screwdriver handle). If that makes the idle jump to/from 1500, there's your problem. If that happens let us know and I'll tell you how to fix it for no cost.
 
Mike R.
 
 
From: mbcoupes-bounces at mbcoupes.com [mailto:mbcoupes-bounces at mbcoupes.com] On Behalf Of Markus Meyer
Sent: Monday, September 14, 2009 6:59 PM
To: Mercedes Coupes Mailing Lists
Subject: Re: [W126 Coupe] Fast Idle Issue 1983 380SEC
 
Greg,
 
As inconsistent as you describe it, it certainly does sound electronic.  I'd think that a vacuum leak would be more steady and consistent.  Not sure where on the 83 model year the module is.  On my gen2 models it is in the pass footwell with the other stuff like the O2 sensor, etc.  Yours may be in between the firewalls?  Anyhow, once you find it, with the car running and idling high, see if you can open the box so you have just the computer board in your hands (still attached to the wires), and twist it to see if anything changes.  The solder joints at this age could certainly be suspect/bad.
 
Good luck!
 
Markus Meyer
mfm at meyerprobateproperties.com
www.meyerprobateproperties.com
Meyer Probate & Properties, LLC
484-919-9762 
 
 
-------- Original Message --------
Subject: [W126 Coupe] Fast Idle Issue 1983 380SEC
From: kashella at comcast.net
Date: Mon, September 14, 2009 9:45 pm
To: MB Coupes <mbcoupes at mbcoupes.com>
I have been having a fast idle issue for about 3 weels now.  I think the problem is the idle control module, but please let me know if there is also something else to check.
 
The car will sometimes idle at the normal 750rpm.  But many times it idles about 1200 to sometimes 1500 rpm.  There is no pattern.  I can start the car and it idles at 1200, then it may settle down to 750.  Or it will idle at 1200 all the time.  Or it may start out at 750 then speed up to 1200.  There are a few times it went as high as 1500 and once around 1800.
 
I do not think it is the idle control valve.  I cleaned the idle control valve.  If the care is idling at 750 and I disconnect the idle control valve the car will speed up.  If the car is idling fast  and I disconnect the idle control valve the car will not speed up.  If I apply a 9V battery to the idle control valve, the car will slow down stumble or stall.  For this reason I belive it is the module.  Evidently the module is not sendng any juice to the control valve.
 
Also does anyone have experiene with BBA-Reman  at www.bba-reman.com in having MB electronics rebuilt?
 
Thanks,
 
Greg Kashella
kashella at comcast.net

 

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