Idle control valve
 

Does anyone have an idle control valve that they know is good that I can test with. I will pay shipping and handle each way. Just want to test if my wierd idle is that or a bad injector. I have a 91 560sel
Thanks
m

What's weird about your idle?

idle
 

Lumpy, worse in p then in d which makes sense, as the least amount of fuel enters the system in Park. Not electrical as far as I can tell scope looks excellent, plus I have new plugs, cap, rotor and wires. I am down to my idle control valve or a bad injector I think. I wanted to test the idle control valve before I blue print the injectors to determine the bad one or ones.
m

anyone out there with a loaner please?

If it is a rotary idle control valve, it is easy to check for smooth operation. The angle of the shaft and thus the size of the port opening should vary smoothly and consistently as you vary the current to the terminals. Any stickiness in action, and you should clean it in solvent, using wood-stemmed cotton swabs to work off any tougher deposits. I used rubbing alcohol.

Not much else can go wrong with it, but lots of opportunities for air-path leaks elsewhere in the rubber plumbing.

Steve

I will try that thanks
m

I have replaced all the rubber by the way and it is not a bad idle just enough to be annoying. I can hardly notice iy anything but P. I think is a bad injector but wanted to make sure with a tester.
I will let you know if cleaning helps.
m

I'm not exactly sure what you mean by "lumpy". If the idle is slightly rough, then I think checking the injectors should be considered. Most idle air valve problems will result in an incorrect/fluctuating idle speed. Check the "Llambda" before you go any further. This is a good way to determine if you have a rich or lean condition. I've seen a few 116/117 engines that develop vacuum leaks at the rubber boots that seal the upper and lower sections of the intake manifold. Keep in mind that there are many vacuum leaks possible, so check the easy stuff first. As you said , the ignition system is good to go, so look carefully for vacuum leaks. Other things worth checking if all else fails: 1. Carbon build-up on intake valves(you can check for this if you remove the injectors). 2. Cylinder compression(It's free if you do it yourself, and it's conclusive). 3. Timing chain stretch. Good luck

check the lamda and it is on the money, did check for vacuum leaks have not found one yet. Did the direct injector blowout with 3 cans of cleaner and the engine is clean as a whistle. So I hope it is the injectors been avoiding that as much as possible but looks like it is all I have left.
m

Did you solve your problem? I had the same problem before my idle went high. It would come and go and fuel injector cleaner and running on the road seemed to help.

not yet, it really is not to bad in D, I am still not sure if it is the injectors or the idle valve. I am going to soak the idle valve next week and see if that helps.
m

How did you go about checking for leaks? Visually or with starter spray?

If former, buy some starter spray and spray all around the hoses and listen for increase idle. Some cracks are so small in those rubber hoses that you can't see them.

I had an idle surge problem that was cured by cleaning the idle valve with laquer thinner (fill it up and shake it well) and then lubricated with WD-40.

G'luck :p

A word to the wise about looking for vacuum leaks by spraying anything at potential problem areas. The propellant in the spray can will find it's way into the air intake and cause a momentary change in idle speed/quality! Don't ask me how I know this!!! You can waste a lot of time chasing ghosts unless you eliminate this possibility. I've used a rolled up piece of cardboard to act as a snorkel over the air intake. Depending on what engine you're dealing with this takes a bit of imagination, but it's worth the effort.

idle valve clean out
 

Okay cleaned the idle valve this weekend after I did the oil and transmission fluid and filters. My Idle in Drive or reverse is marginally better. However, my idle in park is worse. First, the idle rpms picked up to about 850 rpms and it fluctuates around 750 to 950, very strange. I am begining to believe my idle problem is the idle valve. Anyone think I am barking up the wrong tree.

Check the throttle valve switch. The connector is on the intake manifold at the front, slightly to the left, and has three pins. This switch tells the control unit when the throttle plate is at idle, or at full load. I don't remember the color of the wires, but it's easy to test with an ohmmeter. A quick way to check this is to determine which pins are for the idle signal. Just bridge the appropriate wires and see if it makes a difference in idle speed/quality. What you're essentially doing is fooling the control unit. Make sure you determine the correct wires before you do this. The great thing about this test is that it's quick, free, and CONCLUSIVE.

I have an extra idle control valve but it's for a 85 190E 2.3, I don't know if that's the same thing as on yours. I got it for free from my mech as a replacement, but the original was working as well, so I cleaned up both of them and they are like new :)

xp

xp190,
I have no idea if yours will work on mine. I will know for sure when my parts catalog arrives and I can compare parts numbers. I will let you know.
thanks
In response to iluvmils, this would be esay but I have a question my idle in D or R is pretty much perfect would i not see a problem here if it was the throttle valve switch.
m

Martin, probably true, but the switch is so easy to test,why not?

iluvmils,
True actually, I am going to try checking that and also air leaks around the injector.

By the way anyone got a good tester idle control valve I can borrow aswell. I promise to return it!
m

xp190, What part number is yours According to my parts manual mine is 0001411625 i believe yours is 0001411725 so they are not the same but thanks for the offer.
m

I got 0001411725

close but no match :)

sorry

xp

idle control valve
 

Had similar problems with my 85 380 SE, but solved them by:

1. starting warm car which idled at 1600 rpm, spraying brake cleaner around manifold, injectors, etc. to see if idle would change. It did not, so good chance there are no air leaks.

2. Checked tiny bypass hose on idle control valve, the pulled valve and cleaned it with contact cleaner (amazing what black goop came out).

3. Reassembled it, but still no change in high idle.

4. Stopped car, checked voltage with ignition switched on (but car not running) at plug to idle control valve, 11.47 volts, but no "click" when I snapped connector onto valve. hmmm, is valve no good?

5. Yanked idle control computer box, jumped contacts 1 and as well as 4 and 5 at same time (as per MB troubleshooting instructions) with ignition on but car not running. Voila - an audible click from the valve. I guessed it was the computer, pulled the cover with the idle control computer installed (w/o cover - don't touch any metal with it) and twisted it the board. Presto! - smooth idle at 500 rpm.

6. Bought remanufactured board for CDN$350 with warranty.

7. Car is now good.

The valve is simple, but I guess anything can fail (usually the computer though). My tech also suggested checking the TPS sensor on the throttle, it has "stops" for idle and full throttle, if it does not read, the idle control computer will not function properly.

Good luck.

john

Excellent troubleshooting technique John! However, your car is equipped with a separate control unit for idle speed control. The 560SEL in question relies on the CIS-E control unit for idle speed control(as well as several other functions). mhingram, keep at it, don't give up!

Same holds true for M103 engine?
 

My car also idles too high (just sits around 1500 rpm) and when calling my mechanic yesterday, the long distance diagnosis was a faulty idle control valve.

Reading through this post I might not need to install a new
valve - providing the scenario described in this post would also
apply to my M103 engine ('89 300CE).

Any potion this forum can mix up to combat my newly gained headache'?

If a new valve is indeed required, would any of you have the
corresponding part number and an idea what this may cost me
to fix?

Thanks!

To Made in Germany- I don't know the solution so I don't know if it relates to your engine. I also don't know about the cost of the idle control valve. I am guessing very expensive as someone is trying to borrow one to test their car at another string in this forum.
Did your idle go high over a short period of time? Someone suggested a lot of little vacuum leaks around the injectors which would be common over different engines, but I would think that would take quite a while to develop.
I have been busy doing brakes, shocks, and trans fluid and filter but plan to get a scope and check waveforms among the three computers. I suspect something is giving it too much air and fuel. I find it interesting that three of us have the same problem in the same vintage cars. Our cars have had plenty of time for connectors to oxidize, that would be a cheap fix if we could find the right connector. Please let me know what happens with your car.

made in germany
 

Idle valves are @$180 give or take $30
m

m,
Thanks for your response. Gives me an opportunity to budget
for this repair!

Steve,
The idle went up just recently. Not a slow development, but rather from one day to another. I'll take the car in on Monday
and let the mechanic run some tests. Hope I do not need
to replace the valve. Let you know anyhow.

My father had a lumpy idle early on in his '86 560SEL. The dealer replace the main ground cable with a very, very big one. They said the Computer was getting lumpy current, which was causing the lumpy idle. It fixed the problem.

Made in Germany - did you take your car in and what happened?
Steve

Steve,

Took the car in just recently. All it needed was a good cleaning,
adjustment and lubrication of the throttle linkage and Viola, she
runs like new.

Stefan

okay here is the update:
just finished replacing the injectors and the rubber breather hoses. Still lumpy the idle control valve is working fine as is the idle relay. Still have to check the idle switch, will try that next week.

idle surge
 

Okay new update- replaced the main breather hoses and idle control module. My rough idle is actually gone in drive or is almost invisible. However the idle at P is still weird it is not lumpy any more but surges starts at 600 then slowly increases to about 800 then drops to 600. AC switch works as it should, rechecked for vacuum leaks none showed up. I am at a loss. My next step is the OVP relay. Anyone got ideas?

So far changed:
All the engine rubber (needed to anyway all brittle)
new plugs, wires, rotors and distrubutor. (needed to original)
new injectors with seals (original injectors)
new idle control module. (not sure if I needed it but got one cheap on ebay in original sealed package $25 thought it was worth a try unfortunately no effect.)

hey guys very nice discussion i took my car for the lumpy idle too and the dealer said that the supressor switch was bad picked up the car on friday no problem fri and sunday but just before today i felt it again it doesnt do it all the time after the car runs for approx. 30 miles it does it will contact the dealer tomorrow they cant fugure out the problem either this is the third time it went in for the same problem any idea what it could be other than a bad supressor switch just changed the spark plugs last week and teh dealer said the wires are still in a good shape no need to replace it
by the way i have a 93 400 e
thank

new update
 

Okay almost perfect, I used this http://www.landiss.com/mixture.htm document. It is an awesome piece of work (I might add) and adjusted my mixture. I am near perfect, my rough idle in drive is gone and my fluctuationin park in is much better, although it does idle high 850 in P. Idle in D is a perfect 565 so i think I am as close as I can get it. I have a feeling the 6200 feet of altitude played a trick with the computer and adjusting the fuel mixture helped a little. I guess now I need to decide if the high P idle is something to worry about as she is a little richer. I will check my mileage and see if i need to really be concern. Drive idle is sublime again. Happy days!

how do you identify the correct pins?

They are numbered 2 and 3 are the one you use.