Idle controls - PeachParts Mercedes-Benz Forum

#1 04-15-2003, 01:50 PM

I need information regarding high idle on my 1995 E300D non turbo. It idles around 700 RPM or so and drops to normal after throwing a short rev. 2 MD dealers think I'm nuts, that this is normal as does the factory rep and MBUSA. I have put over 100,000 miles on this car and this is a new phenomena I'd like to get rid of. I have spent an enormous amount of money at a dealership in Van Nuys,CA to remedy this but to no avail. Any help is appreciated.

gsxr · #2 04-15-2003, 03:01 PM

700rpm doesn't sound abnormally high. My 603 engine idle speed is 630rpm. Factory spec for your 606 engine is 580-680rpm with the ELR (idle control) connected, and 560-620 with it disconnected (mechanical low-RPM limit). Perhaps your engine idle RPM has been too low for the last 100kmi? Either way, I'd suspect the ELR actuator as a possible problem, or a broken/intermittent wire.

In the factory CD-ROM manual, look in the 606 engine manual for this file: 07.1-1100.pdf

Good luck,

#3 04-15-2003, 04:51 PM

Thanks for the quick response. Perhaps I need to give more info. My car has 217,000 in it. I'm the second owner and this car has always been dealer maintained. I was fond of one dealer closer to me but dropped them after some unnecesary repairs that didn't fix the problem that it had at that time. They did however, treat my wife like a queen. I originally took the car in for normal service and repairs. Front end alignment, oil, brake fluid flush, radiator flush, install new sound shields on the undercarriage, turn signal indicators didn't work, the switch used to flash the brights was out, interior lights went berserk and a couple of minor things. The car did have a pre-existing tranny slippage problem and needed to be rebuilt and I requested an estimate at that time. I also wanted the car detailed inside and out. I received a phone call from the service rep telling me I needed tie rods and new brakes/rotors.
After an enormous bill, I took the car out of the shop, drove down the street and right back to the dealer. The front end was out of alignment, the paint had serious buffer marks (Black car), the cigarrette lighter was broken as was the holder, the car was very loud and it had a new rattle in the drivers door.
Turns out that they sent the car out for the detailing and that the detail shop also broke the cigarette holder and the light. They sent it back for another alignment, sent the car back to the detail shop, repaired the door rattle and put the steering column back together properly and checked out the car. I went to pick it up again and found the front end out of alignment and more buffer marks and the new idle problem. The idle was around 750 Rpm. After some serious complaining, they took the car back and decided that the paint was now bad and repainted half the car. It took one more try to get the alignment right but the idle was still high. The dealer took the car to an independant service shop to get another opinion on the idle. It was then deemed necessary to replace the transmision as that would affect the idle. The service manager and I agreed on a price of $3,400 to put a MB remanufactured tranny and torque converter in. The first tranny slipped as bad as the one that it replaced and they put in another one. I then picked up the car and drove it 2 blocks and turned around. This one slipped too. They told me that this one needed to be broken in. I drove to another dealer and explained the problem. After a mild threat to MBUSA, they sent a serice rep to the new dealer. The transmission slipped as if on cue. They replaced it with another. This one shifts so hard when cold it could injure you. The rep said it's fine as did the dealer. They had no explanation for the idle except that the car was always broken til now. The car gets 2 MPG less than it did and the car is louder at idle than it ever was. The rep said that my tach was off and that was why it looked to be idling at a little over 700 RPM. He had a funny look on his face trying to explain the higher engine noise. Another opinion given to me was that the injector pump was bad. I showed them the dealer reciept for the new one. They ran out of opinions and released the car. What I would like is a tranny that works right and the idle where it used to be. I really need help on this. According the the factory rep, this car is sorta rare. Easy to buy one but difficult to repair because they don't break often enough for the mechanics to have a lot of experience with them. I need some experience with this repair.
All of your help is appreciated and I'll investigate the electrical components.
Thanks to all for their help.
The door rattle was from the dealers valet that had a habit of slamming doors. He broke the window motor mount he slammed the door soo hard.

Holson Adi · #4 04-15-2003, 05:01 PM

Hi Guapa,

Greetings from the Northeast

I don't know how far this guy is for you. However he might be worth your time!

Check out this thread

http://www.peachparts.com/shopforum/showthread.php?threadid=38339

gsxr · #5 04-15-2003, 05:16 PM

Egads! What a story!

I don't think there was anything wrong with the original tranny. That service writer should hang his head in shame. Most likely the problem was - and still is - an issue with the vacuum signal between the IP signal valve (VCV) and the tranny, and/or modulator adjustment (but that should have been done at install). My 1987 has a switch that softens the shifts when cold (engine below 50C), I wonder if your 1995 has that? Hmmm. Something is definitely wrong. I wonder if they got the wrong tranny? The gas & diesels use different valve bodies & other internals. It's also possible that there's a problem with power output or throttle linkage, either will allow for more pedal travel - and tranny shift harshness - with reduced power being produced.

The engine noise is weird. Nothing they did should have made it louder. Wish I knew what was going on there. I'd start with checking the timing chain, injection timing, and injector spray pattern. Oh and also the serpentine belt shock, and perhaps the vacuum pump cover (if it's the old style, the cover can come loose & rattle).

Point to ponder: If this detail shop was bad enough to screw up your paint, they may have been stupid enough to pressure-wash your engine. The water could have caused some damage if sprayed directly at certain electronic components. I'm grasping at straws here, but I know detail shops like to clean engines and I hate it when they do that!

I'd say you need to find a competent dealer or mechanic. I can't believe an MB DEALER screwed up an aligntment - twice! That's pathetic. Perhaps the shop recommended above will be able to help?

Good luck,

#6 04-15-2003, 05:38 PM

Thanks guys. I'll check out the shop.
The alignment took four tries. It almost goes straight now. I'll go to my tire guy from now on. I decided to give the dealer a shot at it as the price is nearly the same. I never would have done it with the high level of incompetence they have demonstrated. The paint damage was from a buffer. Brutal work. There is still another fender to be repainted. I hate the idea of an electrical short. I have little confidence that it will be found to be easy. And for the record, I have 3 diesel Benzs. 1981 300D with over 400,000 miles on it. My wife put almost 200,000 on by her lonesome. The only repairs we have done is 1 used tranny, 1 oil pump and the timing chain. All of these were done at 300,000 miles. Still have the original water pump.Then there is my car. The 1995 troble spot you've been reading about. 2 years ago, the State of CA accidently sandblasted it. Took out the chrome, paint and windows. Ground up restoration was $8,200. Beautifull job done by Precision Motors in Van Nuys. The car that replaced my wife's 1981 is a 1992 300SD. A beautifull car. I want one of these! An S with a thumper in it! This one has 118,000 on it and is as pretty as the black one. I also owned and gave to my mother in law a 1979 300D and after she totaled that I gave her a 1981 300D. This one she sold after the state took her drivers license away for wrecking the other one. As an aside, none of these cars idles the way the black one does now. After all of these cars, the black one is the only one that gives me trouble.

lrg · #7 04-15-2003, 10:50 PM

Guapa,
90s era diesels can be a problem in California because they were never really sold here so the dealer mechanics have virtually no training or experience with them. You are not the first guy in California with a 90s diesel that has had dealer horror stories to tell. Find a good indy mechanic and you will get better service. I realize that I am generalizing with this comment but IMHO dealer mechanics aren't usually the best natural mechanics but are generally well trained so they do well except in cases like yours. A really good indy will either figure out your problems or be smart enough to know when to look for help. Good Luck.

#8 04-15-2003, 11:30 PM

Hi Irg,
I haven't had too much trouble till now. I told the factory rep that they didn't have a clue and no idea where a good diesel mechanic was. He explained to me that the training that factory mechanics get is on current model years and briefly on past years. That did explain the problem. I found the factory to be exceptionally unhelpfull through all of this. They told the story of the dealers being independant. I told them that I saw it as follows.
I put a "factory" transmission in my car by an "authorized" dealer. I told him that the two sleep together. He got my message. One of the biggest problems customers have is this: You need the rep to get what you want. The rep doesn't want to give anything away. You have to walk a fine line between applying heavy pressure and being courtious to this guy because if you make him mad, you lose. If you're too agreeable, you lose. It turned into a battle of wits between the rep and I. He would bring up technical points that I wasn't aware of and I would have to fend them off.
One continuing problem with the car is this;
The engine upon deceleration hovers at 1100 RPM and then continues its decline. The car used to slow down when I let up on the accelerator. Now it appears that whatever engine breaking I had is gone. Deceleration between 3,000 and 2,000 RPM remains as it always was. Now when the car hits 1100 RPM when decelerating, it stays there for a few seconds and then slowly drops to its new idle at a little over 700RPM. I think this stinks. None of the other MB's I have and have had in the past have done this. Nor have the MB loaners I have driven. The factory rep didn't see a problem. Neither did the half dozen dealer mechanics. They all sort of scratched their heads. One quick fix offered by the factory rep was to "fix" my sticking tach. I have to say that it doesn't stick at any RPM. You can hear the enmgine spead at all RPM's. It was a "fix" thatled to the heavy bleading my wallet suffered. Another couple of bucks and it would be curred.
I want to thank all of you that took the time to help me with my dellema. If any of you out there just want to comment, I'd be happy to hear what you think.
Thanks again,
Lou

gsxr · #9 04-16-2003, 12:16 AM

Lou, that RPM "hang" on deceleration could be something related to the injection pump - the ELR included. This will be hard to troubleshoot though, and most place won't want to fix the IP, they'll want to replace it ($$$$). Let's hope that's not the problem...! But somewhere a tranny rebuilder is opening up your previous 3 trannies and scratching their heads saying "hey, these are fine, what's the deal?"

#10 04-16-2003, 12:24 AM

I thought that about the tranny's being looked at too! Serves them right for not knowing anything. I had the fuel injection pump replaced at the dealer 14 months ago. While at the second dealer, a new leak developed with the pump and they did fix that. Seems when it leaks for the customer, he has to replace it. When it leaks at the dealers expense, they find the proper O rings and fix it on the car. Anyway, the pump is ok. I think that the next step is to take the car back to the %$#$ dealer and have them look at it with the info this web page has provided me. I can't thank you folks enough.

#11 04-16-2003, 12:51 AM

A short follow up note. I'm sitting here looking at the inch thick of reciepts I have and I forgot to say I had the serpintine belt replaced at the first dealer. One of the noises they "fixed" was the belt shock that they broke. They repaired it free after I showed them evidence it was fine before they got hold of it. Same with the paint. They claimed at one point that all MB's had buffer marks and that my car was "old". Receipts that the paint was 2 years old and formerly detailed at dealers only, they repainted part of the car for no charge also. Through out this, the service manager at the first dealer was unaware of most of my car troubles that occured at his shop. He didn't need much persuasion to do to honorable thing. The trouble with his service dept was lack of knowledge. His shop has turned into a replace and replace some more till it is "fixed". The second shop wanted to charge me for MB authorized repairs. The foreman of the shop wanted me to pay and try to recoup my new losses from dealer number one. It didn't happen. I got hold of the factory rep and asked him about the "warranty" they had. He had the gall to ask me why I din't take the car back to dealer number one. I told him I didn't have to. I had a nation wide warranty or I didn't. His call. He agreed I could take it anywhere I wanted to after that but that is the kind of grief I have gotten from MBUSA. I want to be free of them and still drive a MB.