Can someone please explain to me the difference between the Euro idle control valve (000 141 14 25) and the U.S. (000 141 12 25). What differentiates one from the other besides $190.00? I ask because I am in possesion of a new valve (U.S.) and would like to know if it is can serve duty in the Euro without harming the Idle Control Unit (which is decidedly different from the U.S. version of the Idle Control Unit). Thank you in advance for any help in this matter.

w.g. canon,

for all of us : what car are we talking about ( Wxxx.xxx? ) ?
I'll try my EPC but I am not shure American carparts are in there...
It's an European version.

Danny

The car is a 1984 European model 500 sec.

w.g.canon,
I am very sorry but my PC had a major crash so I can't view my EPC right now. And if your car is not a W 124, I wouldn't find it anyway.
If you want, I'll ask my mechanic. He is an independant MB specialist and has access to the WIS.

Danny

The electrical characteristics are different (resistance etc). I wouldn´t risk my idle control unit with improper valve.

I would check this out carefully before you install the valve. I have a euro motor in my US 380SL with US injection and idle control. I have a lumpy "hunting" idle. Everything seems to be working correctly. It just won't idle at 500 RPM.

I am beginning to think that the euro engines had either a different valve or controller to compensate for the "hotter" and increased compression.

Do you guys know the idle speed spec for the euro engine?

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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

Chuck,

I know this is a reply to an old post, but I'm going through the archives looking for a solution to a surging idle speed on my 500SL and came across this thread. First, the idle speed for the Euro 500SL is 475rpm...according to my mechanic.

Problem I'm having is I can be sitting at idle (475-500rpm) and the engine will surge anywhere from 100-300rpm. The idle never gets up to 1500rpm, which seems to be typical with the idle speed control unit. The idle speed control valve and unit were both replaced a couple years ago, so I'm hoping this isn't the problem so soon.

It doesn't appear to be an OVP problem either. The OVP was replaced about three years ago as well.

I'm leaning (hoping) toward the ignition control module, which I happen to have a spare in the trunk. However, I'm open for suggestions if anyone has something to offer.

Thanks,

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Don
'85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000
'95 C280 - 174,000

Maybe the tach signal from the ignition control unit is shakey, causing the idle relay to think the idle speed has fallen. Can't hurt to try it if you have a spare. I would also look for a sporadic vacuum leak, or maybe the coolant sensor is getting flakey.

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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

Chuck,

I checked the engine control unit after I drove to work this morning (about 18 miles) and it was barely warm. Checked it again after I got home this afternoon and it was quite hot. So, since I had a spare in the trunk, I decided to go ahead and replace it.

It usually only surged after being driven for a few miles, so I don't know if engine temp is a factor or not. I replaced the temp sensor (near the water pump ???) a couple years ago as well. If this is what you're referring to, then that shouldn't be the problem. However, it may bear swapping out again if this doesn't fix the problem. I drove it to a restaurant near the house for dinner, but probably not long enough to get the engine temp up...i that's the problem. I'll drive it to work again tomorrow, which should give me a feel for whether that's the problem or not.

I'd hate to try and run a vacuum leak to ground, but that will be one of the next tasks to tackle if swapping the unit didn't fix the problem.

I appreciate the tips on what to check out.

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Don
'85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000
'95 C280 - 174,000

I replaced my idle control module and “valve” to cure idle surging to 1200 RPM. I bought them off this site and I think they were for a 500SEC. The valve was aftermarket, not MB. I have an idle of about 600 RPM on the car’s tachometer. My idle is good but I have replaced the ignition control module (cured dying) and the fuel injectors which made the biggest difference in idle quality. But at certain temperatures the idle surges 50 or 100 rpm. If the car runs for 30 min and is up to temp it seems to run great but after an hour on the road it seems to surge but just a little bit. My mechanic thinks it runs very well. He also said the US 93 octane is still too low for the Euro car. One of the MB dealer troubleshooters said that these cars never idled very well. For best results change plugs, wires and fuel injectors. Vacuum leaks are sometimes the problem. These are all my amateur opinions. Good luck.

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Steve
1985 Mercedes 500SL Euro (Gray market)
1995 BMW 520i Euro (Gray market)
1992 BMW 525it Wagon
1994 Honda Del Sol Si

Chuck/Steve,

I replaced the ignition control module and thought that solved the problem...until I got within about a block of the house and it surged again. Going to work in the morning when it's cooler the idle is constant. Come home in the afternoon when the temp warms up and I get the surging. It's only about 300rpm max, but it's still very noticeable. I'm not getting any relay or black box 'chattering' under the dash and in the footwell, so I'm inclined to rule out those units as a source of the problem.

That leaves me with those other things that have been suggested: idle control valve, temp sensor, vacuum leak, plugs, wires and injectors. From those possibilities I'm inclined to think it might be a vacuum leak...rubber contracts when it's cold and will expand when it's hot. I don't know if that's rational thought or not. I tend to rule out plugs, wires and injectors because it runs and accelerates very smoothly, without any missing. Nor does it have a rough idle. This is the first gasoline engine I've had in about 20 years, so I'm reverting to previous experiences in making that analysis. Perhaps they're not relevant to the SL???

Chuck, is the temp sensor you mentioned previously the brass one that screws into the water pump housing? If not, can you tell me where I ought to look and for what?

The idea that these cars might not run well strikes me as bogus. This thing has run and idled (and still does except for the surging) like the proverbial "Swiss Watch". I suppose that's why anything unusual like this is so magnified.

I hate to throw money at the problem like many seem to do. I've got a couple other 'black boxes' that I will drop into it just to see if I stumble across something that might work.

I appreciate any and all suggestions, and won't rule any of them out. One-by-one I'll check them out and let you know when I finally get it resolved.

Thanks again,

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Don
'85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000
'95 C280 - 174,000

Ive got a 86 300E and it has a straight forward after starting climb to 1200 rpms and that is it. I bought a new idle control valve,but havent put it on yet as i was told that it could have a vacuum leak at the vacuum modulator. I havent checked it yet,but i really dont think so.Is their another way to check to see if the idle valve is defective? If it isnt the valve i can take the new valve back.

I don't know the test procedure, but have seen it described in some of the posts. It has to do with checking voltage across the terminals. I've got a nice volt-meter my son uses when he comes to visit. ha!

It's a nice sunny day here in NW Florida today, so I'm going to pull my idle speed control valve off and try to clean it with some carbuerator cleaner this morning to see if that cures the problem. I hope there's nothing I can mess up by doing so, because if there is...

I dropped the under dash cover yesterday afternoon and put my hand on each of the relays and black boxes just to make sure none of them were 'acting funny'. All but one were cool to the touch and none were chattering or vibrating during the brief engine surges.

I'll also check for vacuum leaks in the process.

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Don
'85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000
'95 C280 - 174,000

Don -

With a 300 rpm surge, I think you are either getting a faulty reading from one of the sources that determine what the idle relay sends to the valve, or a transient vacuum leak.

- temp sensor at rear of engine. Will increase rpm when engine is cold - drops it down at about 17C

- AC. increases rpm when compressor comes on

- tach (from ignition control module). sends low signal and relay tries to increase RPM

The wiring from these sources could also be the problem.

- vacuum leak. False air (not monitored) will increase RPM until relay can slow it down.


This is going to be tough to track down.

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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

Chuck,

I made some progress this afternoon. I pulled the filter housing off and began looking for vacuum leaks. I immediately came across a vacuum line that had somehow become disconnected. There is a green and yellow vacuum element to the right of the idle speed control valve with a long l-shaped vacuum hose that attaches to the manifold. The hose had broken down and somehow gotten pulled off. I can't imagine how that happened. Regardless, I just happened to have one of the fittings and stuck it back on.

We drove the car to dinner over in Destin, which is about 15 miles. I pulled into the parking place, put it in Park and sat for a couple minutes. It still surged a couple times, but only about 100 rpm. Same thing when I got back to the house. Nowhere near as pronounced as it had been, but still slightly there.

Now, I don't know if there is a 'memory' that has to be overcome or not. Though the car is not one of our daily drivers, I'll drive it daily for a week or so to see if the idle smooths back out.

I appreciate your, and everyone else's, help in trying to run this to ground. This is a terrific forum, with a wealth of information available and people willing to put themselves out for others. I've bookmarked this thread and will use the suggestions if the problem persists.

Again, my thanks.

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Don
'85 500SL (Euro) - 186,000 w/a complete restoration and engine rebuild at 154,000
'95 C280 - 174,000