This morning again I hit the no start problem again. I hear the pumps running on turning the ignition on, and after some cranking I can smell the fuel. I pulled the spark plug wire on a cylinder & I have a very, very tiny kind of spark. My question is could the OVP limit the spark output at times when cold or maybe the MAS? What about the coil would it fail like that from time to time in cold or changing temperatures? I don't have any spare parts at the moment to try to resolve the issue. Would appreciate any help on narrowing down the problem!

Doing some checking here. Pulled the fuse on the overload relay. Tested fuse it checked ok. Tried starting car without fuse, and it fired-up. I shut it off, and put a new fuse in it, and it started right up ok, but this time without the warning light on in the dash. I wiggled the overload relay around a bit trying to get at things there. Wonder if I reconnected a loose contact? Anyway looked up on Fastlane a Kaehbler is 44.50 & an APA is 44.50, but on All Parts Express it is a Stribel and it is for 109.56. Also, they are all 2 fuse overload relays, and mine is just a single fuse relay. Does anyone know what the deal is on this? Are they the wrong ones for my car here?

hey rebe,

i''m not sure if this applies to your car, but from reading/researching the peachparts forum i found the following info:

OLD style OVP = 000 540 52 45

updated/revised OVP = 000 540 67 45

good luck

check the E.H.A. systm it richens the fuel mixture in the cold to start engine,then leans it out once full operating temp have ben achieved. eha stands for electrohydraulic actuator.its a heavty price new approx $270.00-$290.00. i dont see how the ovp would limit the spark,but replacing an old ovp cant hurt,it does work wonders when installed id try the ovp before i shoot for the eha.

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enjoy life,take the coal that is handed to you and turn it into diamonds. { PHILLIPIANS 4:13}

your observation of a weak spark may not be connected to the OVP, possibly the OVP has a cold solder joint at the junction of the zener diode ,while the fuse is still good. this will give cold start problems.
A fresh rotor ,cap and leads will set a good base for checking and likely solve the weal spark and starting problem.
A warm cis engine should run in Basic mode even with the OVP or the EHA disconnected .
mak

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mark

do a search on my name regarding the ovp. I got the kae brand for $45

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1990 190E 3.0L

The OVP has no influence in spark quality. Measure the resistance of that plug wire as it should have the correct resistance stamped on it.

If that proves successful then check rotor + cap for damage or arching.

A 190 2.6 does not have a MAS. It uses an airflow potentiometer which is a very simplistic version which only influence is fuel enchrichment adaptation on acceleration. There is, however, a cold air sensor at the front of the intake. I would start with the spark issue though.

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I did the repair on the upper timing cover about 3 weeks ago to fix the leakage. At that time I replaced the rotor, distributor cap, & wiring. I, also, put in the oe spec. plugs. I thought I had the issue solved till the other day on the cold snap & it failed to start again. I am in the process of getting a new over voltage relay on the way. I am not 100 percent positive it is the weak link, but I am optimistic it is the problem. The reason being the immediate change of no start to starting right up the instant I jostled it around & removed the fuse etc. I am not sure why they changed to the 2T on the relay? Like maybe the original has some issues or something?? Anyway, if it fixes the problem by replacing the relay, it will definitely be a cause to celebrate!

You are running the older style OVP, that is for sure, but if you are sure that there is a weak spark, that is an issue separate from the OVP.

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

I guess, I didn't mention, that as soon as I got to the over voltage relay access, and was wiggling it around to remove the fuse etc. I removed the fuse, and then I cranked with ignition cable still off. I then had a real kind of spark. I put the plug & ignition cable back together, and without the fuse in the over voltage relay. It started the engine right up like magic with red warning light on in dash display! All time previously just crank, crank, and more crank, and it wouldn't start. I had suspicioned the relay several months ago, after reading up on the forum. It just wasn't at a good time for me to pursue the issue then. At this point I feel it is worth gambling the $ on the relay before digging deeper. I could try a bandage fix or used relay, but suppose I wouldn't know for sure if either was better than what I now have.

I got new Kaehler voltage relay a several days ago. I got it installed. I tried starting the engine and it cranked up right now no problem. It has been quite cold here and snow. I let it set for 3 or 4 days. Then I went to start it in the morning. It barely turned over, and it started up again. From all the previous issues I had encountered with the no start at times. This seems to have fixed my M103 problems. I am happy to get beyond this issue.

thats very interestng that an ovp has solved the issue or at least helped,im having the same issue,my car starts in the cold but then i need to disconnect the e.h.a system in order to drive it,or the car wont move out of its own way it just revs up to 4k rpm,it only shifts and runs correctly when the temp sensor hit just between 40 and 80 celcius all my sensors are new the coolent temp sensor checks out ok,so im clueless,and so is my mechan ic who is just milking me for money 3 hours of diag and he still cant figure out wh the e.h.a system is acting up,its time to brind the old lady into a full service mercedes dealer and have them diag it.

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enjoy life,take the coal that is handed to you and turn it into diamonds. { PHILLIPIANS 4:13}

Just to clarify the thread for future searchers, the OP did/does not have a spark issue because the OVP has no influence on quality of spark.

His OVP has the older style and was most likely allowing the system to fluctuate from open to closed loop due to its failure. The OVP provides power to the ECU which controls mixture adaptation including the engine temperature sensor which has the most influence on cold start scenarios.

mlozzi, what do you mean by it won't move?

If you have to disconnect the EHA, you have some sort of pressure issue. Your mechanic should have tested fuel pressures by now instead of testing your big your wallet is. Instead of paying him another $100/hr, spend that $100 on a CIS pressure kit and do it yourself!

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

One thing I noticed significantly different now is that I hear the fuel pumps plainly at ignition on for starting. Before I honestly couldn't tell if the pumps were doing their thing or not? Also, the quicker starting and no more of the cross crank like trying to start before changing out the protection relay.

i could be dead wrong but the second fuse on the updated ovp has to do with some more sophisticated systems, like asr or something similar...

they just stopped making the one fuse ovp to avoid parts duplication.

that's my story, anyway...

i have spares of one fuse and two fuse..... the key word is spares.... same with fuel pump relay or mas...

never leave home without them

and yes....a bad ovp will cause the no start situation....especially in cold.... you may be able to get away with a rough start in warm weather...

this is just my experience with the 103 engine...

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1989 300ce 129k
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1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus

1994 e320 Cabriolet 108k



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