I took a trip to Nashville this past weekend, and whenever I would slow down, my car would idle fast. About 1100rpm in gear and 1500 in Park. It normally idles at around 450-475rpm. If I shut it off, it goes back to normal when I start it back up.

I am a little worried because it did it a couple of times in the city since I got back, instead of after a 300mi stretch of highway.

Any ideas?

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I am happy to report that I have had the same experience. High idle that was intermittent. I could rev the engine in N and it would settle back down. Shut the car off and it would settle back down most times.

I resoldered the Idle Speed Control module and all has been well for 5 years and counting.

Its not the same as this part here, is it?

PART

That thing is expensive.


I did a search, and could not find instructions on how to resolder it. I am almost afraid to.

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Yup Idle control unit or valve??
I have 380sel too, but I believe this problem has been experienced by a few not only with the 116 engine. I had this problem about 5-6 months ago, disconnected the ICV thouroughly cleaned it out. Disconnected Idle control Unit, everything looked fine on it. So I think in my case the high idle 1100 to 1500 was the ICV.

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**A few Hondas etc... etc... Not Worth Mentioning**
83 Euro W126 380 sel Money Pit (Sold)
91 W124 300e 2.6. (Sold) 3.0 Motor is Much better!!
93 BMW E34 Touring Wagon (Sold) Sweet Car!!
91 300e (Just 200k with Ease.)Best car ever ???(Sold)
90 420sel (Black with Tan Interior) Best car ever!!!!!!!

For me, the ICV was causing it to die at stoplights and during downshifts. Died like I killed the ignition.


You dont suppose it could have a dual effect?

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I need help with this.

Where is the ICM located? How do I solder it? What parts do I solder? Where can I pick one of these up if I screw it up for less than $230?

I am almost afraid to drive it. I was backing into a parking space, and every time I put it in Reverse it would jar the whole car and chirp the tires. Its getting pretty scary.

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The Idle speed control unit is located in the middle of
the car behind the firewall. Black box just beneath the
windshield, held in place by 10mm

The idea is to open up the black box and resolder the
joints, I believe. It's popular solution for the climiate
control unit, seems to work for these also.

Q described this in one of his idle posts, you should be
able to find that with the search.

Q, you have a PM.


For everyone else, I took the ICM out and looked at it. All I found out of the ordinary was some weird brown crusty stuff around a few of the solder joints. Any ideas?

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Here is a pic of the board. I hope it helps, I had to resize it for the small limits of this board.

Attached Thumbnails

 

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My 380 is on its 3rd unit. Happens every 5 yrs or so.

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99 C43
98 S420
99 C230K
01 C240

At $230US that is not cheap!

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I know but you have no choice. I got a used unit once only for it to happen 2 weeks later so you have to go with a new one.

it sucks

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99 C43
98 S420
99 C230K
01 C240

Hey benz inline and mb82! I have a ques now that you two have the same car. I also did the resolder trick on the idle control. Worked good. Also did the climate control unit w/ same sucess; just tricky getting the buttons back on. My ques is the cruise control: I took the accuator apart and cleaned it and resoldered too. Never took the amplifier out though. I can feel it trying to hold so I know it is getting voltage but not enough to advance the throttle to set speed. In other words, it slowly slows down till I tab the brake and I can feel the gas peddle hit my foot. Being that the car is so heavy and that actuator really has worked in the past to keep set speed, can I assume that it is toast and have to shell-out 230$ for a new one? 82 380 sel w/ 125k. Thanks les!!

If you are getting a straight 1100/1500, then you have probably lost power to the ICU. Power comes from the OVP relay, which is a red "ice cube," then via a silver "ice cube" that feeds both the ICU and the lambda unit. A quick test is to see if you have 12V between Pins 2 and 4 of the ICU's socket. If not, work your way back to the OVP.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

How do work my way back? The pins aren't numbered on the ICU.

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