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many thanks 281lxm

it seems to have settled down to 600-650 in gear and 750-800 in park. this is probably the lowest its been in the 20 plus years I have owned the car. still has a slight shake at that rpm. will have to tweak a bit further. Cheers
 

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I'd be happy enough with that. I see about 500rpm in gear, but pretty sure yours is just about within spec. Mines almost a bit low but I like it.
 

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@Stewpot , do you happen to know (or know how to find out) whether there was much variation between ICUs for different variations of the V8 Gen2 models? For example, I have a '91 560 SEL, California edition. When it comes to emissions and electronics, I've found a couple of differences with the CA cars. I'm a bit at a loss as to how to figure out what the car *should* have.

Background: I've been slowly eliminating other possible causes for my car's combo of high and somewhat rough idle when warm, and the ICU is about all that's left. :) I've completely refreshed the intake, refreshed the air guide, replaced the intake gaskets, and replaced all the vacuum hardware. This has solved some other problems I was facing (yay!) but the idle is still problematic. I think the ICU is next. I want to make sure I get the right one for the car.
 

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Hello Robert D.
First of all, many thanks for assuming I know what I am talking about....a great leap of faith. Its a seattle day here in sunny Florida, so I have some time before looking for my "brolly."

My first instinct when the idle goes up is to check the two vacuum hoses that run along the fuel injectors. They have a habit of splitting on me. Then I check the idle air control valve. this time, both issues were good and before checking sensors and electrics, I changed the ICU and voila, it worked. Then I did a tune up and things got even better (six years since previous one, my bad).

I know nothing about California cars other than the obvious. My new (rebuilt) ICU came from Programa in Boca Raton, Florida. They enjoy a five star reputation. Their web site (programainc.com) shows that the replace for your ICU is 006 545 85 32. Its a bit pricier than some of their other ICUs. You might want to talk to them, very friendly and the chief technician to ask for is Joe. He might be able to clarify the California aspect.

Perhaps others will chime in if they think the issue might be other than ICU. Hope this helps and good luck.
 

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and to cap this thread on a happy note, when I first got this car my gas mileage was about what the sticker said at 13 mpg city and 15 hiway, which is why the original owner paid the gas guzzler tax on it. When I switched to non-ethanol gas (a bit more expensive than premium) my mixed mileage went up to about 20. Hooray. Then letting a tune up go for so long, it drifted down to 15 again. Now with new ICU and tune up we are back to 20 and smiles.
 

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Well, my brush with "high idle hell" was not as difficult as I had expected. Issue was not bad sensors, electrical short, or stuck Idle Air Control Valve (IACV) as I had suspected. It turned out to be a bad Idle Control Unit which brought the rpms down and then a tune up (cap, rotor, coil, plugs, wires) and its starts much easier, is much smoother and idles at 650 in gear and 950 in park. I have my car back.

Now on to refreshing the EZL thermal paste.
HI You may be my Idle hell savior. So I replaced plugs, wires, cap , rotor and Coil. Went through all sorts of diagnostic with vacuum, sealsc leaks, ICV all to no avail. Next step is to be what you did, Idle control module. Mine is behind the glovebox. Was yours there?
Or was it above the fuse panel. If it was behind the glovebox.

PLEASE Please give me some assistance on how to get to it. Jack in Los Angeles. email me if you can [email protected] Thanks.
 

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Hi Jack R, Ian
I have a 500sel 1985 and its up against the firewall. good luck, hope its that simple. This is a good example of why car model and location are a good thing to have below the avatar and the "joined" date. Ian, can you advocate this example with the Crickets of our new world
 

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Hi Jack R, Ian
I have a 500sel 1985 and its up against the firewall. good luck, hope its that simple. This is a good example of why car model and location are a good thing to have below the avatar and the "joined" date. Ian, can you advocate this example with the Crickets of our new world
HI all. If you can not reach it directly what would I need to remove to get to it.
 

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Hi James. Well it seems that your fuel distributor and mine are the same. So No one in months of research, and diagnosis came up with this sugestion. I did the voltage test and got .3 it was not what you said it should be. However my idle is like this.

On start up it is about 1050 rpm and goes up to about 1150 rpm. it stays at this no mater how long the car warms up. When I drive it it is normal. Runs good, no stumble on acceleration. When I put it into gear D or R the idle drops to about 900rpm. That is where I am at. Jack
 

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What car do you have Jack? If its a 560 it'll just be in the passenger footwell and easy to get to.

It is a 1986 560SL The Module is behind the Glove box. I can see it but not touch it,
The Question I put to the forum is there a proper way to remove it without damagind other components, Jack
 

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Ah it's an SL? I'm sure we do have some members with this car, but why not post in the R107 section. Those guys know their cars inside out.
 
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