I hope you'll bear with me but my problem goes like this:

About three months ago, I had a local shop, who does only mercedes benz's, repair my long-running problem with the oil leak and noisy vibrations caused by a bracket connected to the airconditioning compressor. They installed new oil seals and removed all broken bolts of the bracket and replaced it with a new and sturdier type. This were all done with the engine out of the engine bay. After, all were done, they returned the engine and did the regular oil change and tune-up.

The repair was well done since no leaks and noisy vibrations ever recurred after that.

However, I suddently developed a hard starting problem. I returned it to the repair shop and they adjusted fuel and air mixture, etc., and somehow concluded that my starter is failing. It soon did fail and I immediately replaced it.

The replacement cured the hard starting but it returned after a week. Next I had the injectors cleaned. That was fine but the hard starting returned. To save the effort and money, I just adjusted my style and started the engine while softly pressing on the gas pedal. That was fine for a while. Last November, my aux fan relay got burnt. That was replaced, but electricity seemed to fluctuate. Tapped the OVP and secured the new relay upon the advise of my electrician. It worked.

One December morning, apart from the hard starts, I suddenly encountered, a very rough idle at start up. So rough that the engine will cut off whenever I turn on the airconditioning or release the gas pedal. This somewhat normalizes when the engine gets warm. I say somewhat, because it is still not a perfect idle because there's an occassional shudder that I feel. Cruising, though is not a problem.

I sent this to another shop (mercedes benz only) for tune-up. They changed the spark plug and adjusted fuel and air mixture. They cannot get the idling to run perfectly as it should. They came up with the conclusion that the control unit should be replaced by putting another unit.

Because it was expensive, I tried to get a second opinion. I found a shop who said they can diagnose a bad or good control unit. They did not see anything wrong with it. I don't know if I was glad to know that there's nothing wrong or was just glad that they said what I wanted to hear. They did, however, cure my stumbling idle at start up by increasing idle speed which the previous shop said they cannot adjust because of the control unit. But there is still the hard starts and occassional shudder even when the engine in under normal operating temp. They said that the occasssional shudder might be the engine support. But I replaced this about 3 years ago. Do engine supports fail within that period?

This is still bearable but can anyone please point me in the right direction. If it is indeed the control unit (ouch!!), there goes my money for the paint job. I've checked the OVP and the fuse seems fine. I've read, though, that they can fail internally. I'm not a technical person. so an explanation on what my problem (causes/solutions) in layman's terms will be appreciated.

We don't have any 230Es over here so I'm going to guess that it is the same basic setup as the 190E 2.3. If the setups are the same, the first shop was right about idle not being adjustable. What the second shop probably did was put restrictors or openings in the idle circuit to bypass the idle air valve. If you do a search, we have had discussions about this problem. I don't think there is aproblem in your control unit. Members here are suspecting the idle air valves to be either getting sticky or failing electrically. I always have trouble with the search, but try looking for idle air valve or idle air management system.

Good luck,
Peter

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Auto Zentral Ltd.

An additional thought. When you have the hard start, remove the air cleaner, remove the connector from the idle air valve and apply 12 volts to the valve. If the var starts, you know you are barking up the rigth tree.

Peter

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Auto Zentral Ltd.

I would first replace the distributor cap and rotor unless they have been replaced in last 30k miles or so. It sounds like your mechanic may have already done the EHA adjustment, but if not I would try that (do a search for EHA and you'll see what I mean). I would also look at this link:

http://www.mbca.org/pages/tech/MBCA_Rough_starting.htm

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2005 Mercedes C230k sport sedan, 6 speed
1987 Porsche 924S - 968-engined track car

Dear Autozen,

Yes, I think this is basically the same set-up as the 190E 2.3 with the 102 engine. What do you mean by idle air valve, is this the same as idle contol valve resting beneath the air cleaner? If this is the same, I replaced this about 2.5 years ago. Before that time my idle surges above 10 and sometimes goes down to less than 5. And yes, there was that occassional hard starts also. This was cured as soon as it was replaced. Will it necessarily fail within that time frame? I've read that cleaning it with carb cleaners can be an alternative. Would you agree?

Dear Schumi,

I like your name. It reminds me that the F1 2005 season is about to start. I've already replaced the distributor cap and wires 3 years ago. And yes, I think it was the EHA that they adjusted (below the air cleaner). I've read the link that you've mentioned before. However, I'm not sure if this is what I would like to do in the meantime given that it cover-ups the problem. Rest assured, that upon exhausting all possible remedies, I'll definitely give this a try.

Thanks to both of you. I'll keep you posted if there are any developments.

Last Saturday, as recommended, I cleansed the idle control valve with carb cleaners and was able to dislodge a lot of dirt inside. Reconnected it and while the air cleaner was off, I tried to start the engine. That did not solve the hard starting. What surprised me however, was that the throttle valve kept on moving erratically (closing and opening) while idling. If I recall it right, it should not open at all while idling. I disconnected the CIS-E control unit and the throttle valve stopped moving. Kept it disconnected and used the car that day without any problems. In the evening, I took out the control unit, OVP, and another relay with some German name on it "Kalstart". Opened everything and sprayed it with a contact cleaner that I just bought and reconnected everything back.

I don't know if that solved the problem, because I did not take another look at the throttle valve.

But what I'd like to know is what causes the throttle valve to act that way? I'm tending to believe that the control unit is my main problem since my idling somewhat smoothed out when it was not connected.

I would appreciated anyones help, pleeease!!!!

[B]bump ... anyone??? I opened the air cleaner last night and the throttle valve is still moving erratically while idling.

what seems to be wrong?

i'm probably referring to the throttle plate instead of valve. it's not close when idling but its opening and closing repreatedly. any ideas????

Brought my car to a mercedes repair shop (the one who did the oil seals, see first post). I originally planned on buying an OVP from them (guessing it might solve the problem) but decided first to have one of their mechanics look at the throttle plate. He tried to remove the connectors to the idle control valve and the plate stopped moving, then he reconnected it back. The throttle plate erratically moved again. Then he disconnected the OVP, the throttle plate stopped moving again. Then he reconnected it back and again it opened and closed repeatedly.

Swapped the old OVP with a new one and that did not solve the problem. They don't know how to check the ICV and no stock is available that they can use to test if the ICV is bad.

This is really driving me nuts....

Have them check the rubber boot under the AFM, that is the Air Flow Meter you are refering to the throttle is underneath it. There is a rubber boot on the bottom of the AFM that is between the AFM and the actuall throttle body. This tends to crack and is a $20 part, mine is actually starting to crack. If it cracks it lets air by the AFM and into the throttle body below. Thus bypassing the AFM and its ability to tell air flow. Also check for vacuum leaks on all connectors. I replaced all rubber connectors under the hood and idle quality improved greatly. I also had a bad one or two on the HVAC system in the car and fixed them and all ran better. Sometimes it is the little things that get you.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

Dear mctwin2kman,

Thanks, I will do that.


Dear forum members,

Any other thoughts???

mctwin2kman,

By the way, I noticed you have a 1986 190E 2.3. Is this a 16v? Otherwise, I think we have the same engine, m102. Have you seen your throttle plate move so erratically before when you have not changed all the rubber thingy?

Thanks

I wish it was a 16V! But yes we have the same M102 engine. I have done a lot of work on mine as far as getting it back up to snuff. Did the Head Gasket a few weeks ago.

And no my AFM Plate stays pretty steady at idle. I also cleaned all inside my AFM unit when I had it off for the head. But no it does not move much at idle if at all.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....

I have a euro 230E. The engine mounts went in 3 years. The passenger side one was the one that went bad becuase of the engine twist during acceleration. Too much stop and go traffic and red light races I gues . The original lasted to 130k km. Bizzarre but, judging by mercedes recent quality, not surprising the new ones went so soon.
If you want to see if yours is bad. Pop the hood (bonnet) and hold the engine in gear with the brake and give it some gas. If the engine twist significantly you've found one issue at least.
The hard start could be your battery and/or a bad cold start valve. Get yourself a multimeter and see if your battery is 13v or above while idling or 12v or more after sitting for awhile. I think someone posted how to test the coldstart valve somewhere so do a search.
Hope this helps...

Dear mctwin2kman,

Me too! I've done a lot of things with car since I bought it (2nd hand) to make it look, smell and run like a MB would. From upholstery, top engine rebuilt, suspension (F&R - bushings, shocks, mounts, the works), new tires and wheels, H&R springs, radiator overhaul, new alternator and the list goes on and on. I was planning on having it repainted this year and having a side claddings installed. But with a possibility of having to replace the control unit, I'm now putting it on hold in the meantime.

Dear yal,

Thanks for the input. As mentioned above I've already replaced the engine mounts. This was done 3 years ago. Does it necessarily fail that soon? For the hard starts, the battery might be a good shot. Because come to think it's been three years since I replaced it. But wouldn't a slow cranking to no cranking be more of a symptom of a failing battery? Mine cranks fairly well. It just takes longer like, about 5 seconds or more. If it does not start the first time it's fairly easy the second time (1 click). The cold start valve has been tested and that's OK.

any more suggestions?????