My E420 is stalling!

[screedchan]

My 94 E420 has been spontaneously stalling from time to time. It is pretty random, except for the fact that it never happens at speed. Usually, it is when I am sitting at a stoplight. I almost always have the a/c on out here in California, so that places a little extra load on the engine. Also, it has happened a couple of times when I approach a sharp turn at a decent speed. I think that the combination of falling revs and the extra load of the brakes and power steering sometimes causes the car to stall. My mechanic intends to clean out the throttle body when I bring it in for the 120,000 mile service, but I was wondering what else might help.

I am also dealing with a check engine light which has been well-chronicled here on the forum, but I do not think that the two issues are related.

Thanks in advance for any helpful suggestions.

[jylee]

The some problem has happen on my wife's 300E with 103 engine about 3 years. I has changed the fuel filter and rotor, I don't think either the new filter or the rotor fixed the problem, but may be the root cause of the problem is fuel pumps or relay.

The problem has gone away on its own after about 2 months later, and it has not reappear.

jack

[G-Benz]

I had that problem surface in a similar manner...stall out when driving, making sharp turns (especially with the A/C on). Eventually, I had hot start problems added to the mix.
Thought it was bad gas until I joined the forum and was enlightened.

Replacing the OVP relay cured ALL of the problems.

[mbdoc]

Many times CLEANING the throttle body area with a scotch-brite pad will eliminate the stalling problem.

[David C Klasse]

Yup, sounds like your OVP is the culprit... do a search and you'll find all the info you could ever need on it.

MBDOC,
Where is the throttle body... is it where the accelerator opens "whatever" to let any given amt (accelerator position) into the engine? I ask this because sometimes when I am going very slow and turn the wheel all the way, putting resistance to the wheels, the car almost feels like it is going to stall, never has, but this happens all of the time. Thanks.

[mbdoc]

To start with the E420 doesn't have an over-voltage relay like the E320/C280 cars! Stalling can be caused by carbon build-up on the throttle plate. The throttle body bolts directly to the intake manifold. There is a small hole drilled into the butterfly(M119) and if carbon builds up on this hole the car will die at times!

[screedchan]

Thanks for straightening this issue out, MB DOC. If, by chance, I clean the throttle body and it still occurs, is there anything else I can check? Thanks.

MB DOC, would you have any idea why my 2002 C230K with 4000 miles also has this problem? My dealer doesn't know. I've been told that there is no OVP in this car. They ran it through their system checking for errors but came up with none--directly corresponding to the no "check engine" light while experiencing the stall. This happened after driving on the highway for two hours with the AC on a fairly hot day and rolling into stop-n-go traffic. Once the engine sat for awhile, I haven't encountered the problem again. I can't believe that MB doesn't have a plethora of real answers to an issue that seems to have been around for decades in this company. The only other person I know with a new C class has experienced this problem as well. No "check engine" light for both of us. The engine coolant temp was at 90 F. I didn't stall the engine due to user error. (My friend was told it was an "automatic transmission fluke", I was told it was my fat foot touching the brake pedal and the clutch at the same time.)

Not to mention this is NOT the only dangerous problem I'm finding with my new car. Funny ... my last car, a Toyota, is 20 years old and I've never needed the hazard lights. In fact, I pulled the fuse on it 5 years ago. However I seem to be reaching for that red triangle rather frequently in my new Mercedes. I don't want to be negative but I'm just a bit dissapointed from a new customer perspective.

[centaurus3200]

as a good newbie, i did a search and it brought me to this thread (and a couple others). my girlfriend's cousin is flat out sick of her 1994 E420 because it just stalls at random. she even GAVE it to her kids (30 somethings) and they don't want it.

so, from what i gather, i should first clean the throttle body. worst case is that i need a new throttle body. the car only has 29,000 miles on it. in a post, it says that the computer was not properly calibrated from the factory. does this cause the car to stall or just run rich? i hear chip talk going on here. this seems like a far cheaper idea than a reflashed ecu. or can i give my ecu as a core and get a "corrected" ecu pretty cheap?

wouldn't a rich running car eat O2 sensors and converters like no tomorrow?

can i get an aftermarket maf that could be calibrated to adjust the rich condition? we ford guys have pro flow, i even have on on my SHO.

i am learning that all cars are fairly similar. being this mercedes E420 and my SHO are both pre-0B2 (pre 1996), we have a lot in common. on my SHO, erratic idle can be caused mainly by the idle air bypass valve. it's a mechanical spring loaded sensor that continuously adjusts idle for smooth operation. problem is that as it gets old, the spring gets out of whack which results in erratic idle and stalls. i know my gf's 1997 audi A4 has an IAB, does this mercedes?

does this stalling problem result in erratic idle (jostling 250 rpm or so until stall) or does the car just flat out stall. if the car dies out of nowhere, can it be the cam position sensor or the crankshaft position sensor?

i am very eager to hear your responses. i sure hope i can nab this car as my SHO now has nearly 123,000 miles on the clock. time for a new sled.

see ya,
Robby