Last month I decided to tackle the high idle issue on my 89 560 SEC by removing the Idle Control Valve and cleaning it with carb cleaner and lubricated it with WD 40. When I removed it I inspected both elbow hoses and noticed one was cracked so I replaced it. After I got it back together I noticed the car was running rich (occasional smoke at idle more significant at startup).
I adjusted the fuel mixture a little leaner but it didn't help. I adjusted a few more times 1/4 turn each before I was at full lean. It still smelled real rich. I took it out for a highway run and noticed when I decellerated the engine speed seemed to surge between 2000 and 1500 rpm. When I got home and put it in park the idle speed jumped up to 1500 rpm. I got out of the car removed the electrical connection to the ICV and idle speed increased to 2000. So I replaced the connector and looked at every vacuum line under the hood, with no luck at finding other cracked vaccuum lines. I drove the car once more and the idle speed has increased to 2000 rpm. I'm stumped...whats causing this idle and unnecessary richness?

D

There are lots of posts on this problem.

It is a very bad idea to crank away on the mixture. The mixture is controlled electronically, and turning the screw causes the system to try to get it back to where it thinks it should be.

To get you started, search on:

on-off ratio
coolant temperature sensor
OVP relay
oxygen sensor

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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

there is a relay that runs the idle valve.on your car it is under the angled plate in front of pass's feet[pull up carpets] if you replace this and idle still at about 1000rpm you will need the valve as well.very common i often have to replace both.you will never get mixture correct until you fix this problem.seen lots of people try to sell cars with this problem and they just lean mixture down to control idle,which works for a while.

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David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg

On that chassis , classic OVP fault.
Check the fuse on top.
ABS ligfht ON ??????????

Thanks for the feedback. I beleive I found the OVP fuse (clear cover, red 10 amp fuse). I pulled and inspected and it looks perfect. No ABS light

I understand the idle valve solve but don't understand why the idle speed was at 750 after I cleaned the valve but the car started runnning rich. Now it's rich and idling really fast. Could this control unit under the carpet cause the engine to run rich as well?

Did you knock a vacuuum hose off when you pulled the valve? Are all the wires re-connected correctly? Are any broken, which happens when you move old brittle wires? Is anything interfering with the throttle linkage?

If you want to fix this yourself, I suggest that you do the following:

- go to Sears and buy a digital multi-meter with a Duty Cycle setting.
- do a search on this forum, or buy a CD or manual, or otherwise get some information about troubleshooting KE-Jet injection.

Then use the new meter and your new-found knowledge to determine what is going on:

- duty cycle reading
- coolant temp sensor reading
- oxygen sensor voltage
- voltage at the idle valve
- current going to the EHA

I think your car has more than one problem. Until you get an understanding of how the pieces of your injectio system work together, and some real data, all of us are chasing our tails trying to help you.

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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

On my opinion, you mixed up the air fuel mixture. It is because before you clean up the ICV. It is no problem, running normal, right? The idle was running funny because the cleaner or WD40 still not completely dry, then you drove your car.

Now, you need to set up the right air fuel mixture, then your car should be no problem. Good luck

Could be a simple vacuum leak but something more in depth. Send me your vin and I can give you some documents.

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Problem solved. Long story short the ICV failed after cleaning. As I mentioned in the earlier post I had a higher than normal idle 950-1100 since I bought the car and after I cleaned the valve and reinstalled the idle was high and car was smoking black smoke. I took the car to my local indi he pulled the ICU looked at it under a magnifying glass and every thing looked good. He replaced mine with a known working unit and the idle speed was still at 1500-1800. He tested the OVF with his DMM and it was fine. After all these steps he stated "Looks like you have a bad ICV" I ordered the part online and replaced it tonight. One turn of the key and the engine fired right up idled at about 1k rpms for a minute or so and then settled down to 650-700. I took it out for a test drive and each and everytime I came to a stop it had a perfect idle.

Lesson learned, after cleaning the ICV and the idle speed got worse I should have just replaced it..

D

nice man, good work

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)