Okay thanks. I'll take a look at it. Also, can you recommend a repair guide.

Have a similar problem with my 95 C-280, along with various electrical "gremlins." So far, various dealerships and techs have replaced plugs, wires, engine wiring harness and located and repaired 2 vacuum leaks.....still runs rough and misfires! None of these folks have suggested that I replace the 3 coil to plug connectors- I am finding out here on this forum that this is one of the least expensive things to check and should have been done early on. I will try this- followed next by the OVP as Mr. Dalton suggests.

By the way, the vacuum leaks and frayed wires on the engine harness were apparently caused by mice. I have been told to sprinkle whole cloves in and around the engine compartment, floor mats and trunk. The smell of this spice irritates rodents and will keep them out.



If these two things don't solve the problem then it's time to say goodbye to this car.

I did check the links and then looked at the OVP im my car (95 C-280). The part number on the OVP is 000 540 67 45. The unit also has a M/B logo anda large letter "S" logo on it as well (Siemens?). I do not believe this unit was ever changed since I owned the car (purchased in May 1999 with 47K on it).

Is this in fact the "new" part number or should I replace it? I notice that online if you enter the part number the unit that comes up is manufactured by K-A-E.

How can you say it had never been changed?? If it was never changed , it would have the original # on it. What you have in there is NOT the original OVP.

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A Dalton

OK. I purchased the car as a Starmark Certified Pre-Owned unit. They did a bunch of work to it for the certification process and I think I have a copy of their internal RO. It is possible that they replaced the OVP during this process. I will check it out. Since this is not the original unit I should probably leave it be and try something else.

Don't know who changed the part..I am simply telling you they did not have the new modified relay changeover until after your manufacture year,....so ...Somebody change it and that also does not mean the new one is now not failing..the points wear out and the sockets get corroded..like any electrical part.
What I do say is IF you have the old relay, I ask that it be changed REGARDLESS of it's condition b/c they were an inferior part..which is why they changed it in the first place. And it was probably them b/c BENZ knows all about the original OVP problems..Everyone does ....
It was probably the FIRST thing they did before putting it out for sale. I am sure they did not want a nice StarMark Benz on their lot that would not start !!! And if your car still had the old OVP and was a Star Car, I would be right in their face about it...
Most Techs have the new# relay in their tool box so they can just pop one in there on a complaint like yours.. simply b/c that is much easier than trying to find an OVP glitch w/o a scope and testing equipment.
They are that NOTORIOUS !!!!
So, next time you have the problem, I suggest you tap the relay and retry ..
If YES, I would chance the price of a new OVP..that's all.
I would also pull it and look for burn eveidence at the pins and I would pull the fuse on top and clean the spades..that may be all that is needed.
Or have it diagnosed by someone with the equipment to do so.

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A Dalton

OK, I will try those things you suggested. This car had run really great for several years and has just started acting up recently. It's built like a tank, has no rust on it and looks great. I'll be very happy to keep it once I get these bugs worked out.

thanks again

Very Good..

It is a great chassis and drive it til it rust to death.. you will then be way ahead of the car game..

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A Dalton

Started the car up---it had a rough idle. With the engine running I tapped on the OVP a few times with a screwdriver. This had no effect. The rough idle continued. I'm going to order the plug connectors. Nobody around here stocks them.

You can get them right here [ top of page]
Make sure you just get the ones under the coils [ 3 of them]
I am surprised no one changed them when they did the plugs and wires..that is standard procedure on a 104 with DIS ignition.
Might waht to look if they have the correct plugs while you are there ..you do not want Plats in a 104 , for sure.

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A Dalton

Thanks. Do you know of a website where I can look up the actual M/B part # for the connectors?

The plugs that were installed are Champion RC12YC. They have a single tip electrode and does not say "platinum" anywhere on it.

You are on the web site for parts ..right at the top of the page

You also have Resistor plugs in there ..not my preference.

http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2FG17RJ3A2FL0XCZHH&yearid=1995@@1995&makeid=MB@@MB@@X&modelid=C%2D280%2D001@@C+280+Sedan&catid=F@@Engine+Electrical&subcatid=F1010@@Spark+Plug+Connector&mode=PA&subcatid=F1010@@Spark%20Plug%20Connector&applicationid=000357354&source=www.peachparts.com&clientid=catalog.mercedesshop

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A Dalton

Replaced the coil to plug connector on the middle coil. The old one had evidence of arcing on the inside. Also found that the air intake crossover pipe was not seated correctly into the boot on the manifold. Corrected both of these situations and now the car runs great- finally! I will change the other 2 connectors next week.

There is still a little bit of revving up and down at idle, which may suggest another small vacuum leak somewhere. Until I can check that further I can at least drive the car and live with it.

After $2000 in repairs (engine wiring harness, EGR valve, plugs, wires and diagnostics) and lots of posts and replies (thank you!) I have learned that next time misfires happen start with plugs-coil connectors-ignition wires and sp connectors-coils, etc. In other words the least expensive components first and work your way back! Wish I had done that but what the heck did I know?

Thanks for your help....


My next project: the driver's door lock linkage has either broken or come undone as the lock cylinder will not open the door or operate the power door lock system. Is it a huge deal to take the door panel apart to get at it?