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1992 300E Engine stalling after cold start. Need help

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monarchd's picture
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Hey everyone,

In short the problem with my 1992 300E only occurs during the first 10 or so minutes after cold starting. When I drive and get off the accelerator when approaching a stop sign or rolling down a hill, the RPM needle jumps to 0 and the engine stalls once the car slows down.

Now here is a more detailed explanation:

Again, this problem only happens after cold starting. I think this is KEY when diagnosing the problem. I've had it at several certified Mercedes Benz dealers, but none have found anything because the error simply doesn't happen when they check it out. Also because these older models don't have a hard drive (i guess), the error is not recorded and thus makes it so hard to diagnose. Here is some more info on the car:

It's a 1992 Mercedes Benz 300e. Automatic transmission, 125,000 miles. Get's serviced regularly, and otherwise is in a very good condition. Again, I get oil changed regularly and only tank premium gas (93). It runs at around 600-700 rpms when idle. I bought this car new.

Here is what happens in a more detailed descriptions (please bare with me): When cold starting (after the car has been sitting around for 5+ hours) I drive around, and i guess the cold start protection at first doesn't allow me to go very fast. Anyways, I go slow until it finally shifts up and continue driving. I go over a hill and naturally get off the accelerator to roll down. Immediately after i get off the gas pedal, the RPM needles JUMPS (that's right, JUMPS) to ZERO. However the engine doesn't stall at this point. IT STALLS when the car slows down at the base of the hill. That is, the car doesn't stall while I'm moving at a certain speed, only once it falls bellow a certain speed. Since this occurance is quite frequent, I learned to prevent the stalling of the engine, by accelerating furiously. Sometimes, if I'm lucky, the rpm needly gently moves to the regular RPM for the specific gear, and the car runs fine. If I do nothing, or I can't accelerate and I have to slow down, the ENGINE STALLS, all the lights turn on and the steering wheel is hard to turn.

When this happens I stop the car, put it back in PARK, and try to restart the engine. Sometimes it takes a few minutes, other times it starts up immediately.

Again, after this, sometimes the problem doesn't occur again, other times the same thing happens at the next stop sign. But after about 10 or so minutes, the problem is gone. Note, this also happens when the engine has reached normal operating temperature of around ~80 degrees.

While this is the main problem, I've also encountered another problem twice when I'm at a complete rest, and want to accelerate and then the engine stalls immediately. This problem is less frequent yet ALSO only happens during the first 10 minutes of cold start.

I really want to STRESS that the problems ONLY occur after a cold start. I've searched the board and seen people with similar problems, however the suggestions didn't really make sense to me, nor do I think they apply to this problem. If this ONLY occur during the first 10 min after cold start, what could be the problem?

What specifically runs during the first 10 minutes after cold starting that does NOT run otherwise? What happens that simply doesn't happen when the car has been running for a while? I've tried letting the car warm up for several minutes, yet the same problem occurs? This is simply mind boggling and I don't know what to do. Dealerships can't help me as they can't diagnose it. The car overall is in a good condition and I don't want to lose it.

I'm completely at a loss, and hopefully some of you can lead me in the right direction. I would appreciate it SO SO SO much. It's a beautiful car, and I'm scared to drive it, get stuck in traffic, and have it stall in the center lane :(.

Again, thanks in advance for your help and for reading this.

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wbain's picture
Haymarket, VA
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Joined: December 1st, 2003

Posts:
891

Vehicles
1965 220SEb

Is this an M103 or M104 engine? (I've forgotten the switch over year). Is the check engine light on?

There are many posts on mercedesshop.com on diagnosing M103 engine problems with the Bosch KE system.

It could be something as simple as the throttle position sensor or a vacuum leak.

http://www.mercedesshop.com/Wikka/DoItYourSelf

http://www.mercedesshop.com/Wikka/M103VacuumLeak

Please give us some more info about your car.

__________________

1965 220S, 1999 Volvo V70, 2002 FORD Crown Vic, 1972 350SL Euro 4 speed.

Anonymous
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wbain wrote:
Is this an M103 or M104 engine? (I've forgotten the switch over year). Is the check engine light on?

There are many posts on mercedesshop.com on diagnosing M103 engine problems with the Bosch KE system.

It could be something as simple as the throttle position sensor or a vacuum leak.

http://www.mercedesshop.com/Wikka/DoItYourSelf

http://www.mercedesshop.com/Wikka/M103VacuumLeak

Please give us some more info about your car.

Hey thanks for the reply. I can't get that engine detail until tonight. But I'll post it as soon as I can. And no, the engine light is NOT on.

I'll certainly check out that vacuum leak thing on that site. Though I'm highly skeptical. Granted I don't know a lot about vacuum leaks, I would imagine it's a problem that would be persistant, and NOT only occur the first few minutes after cold starting.

Also something I forgot to mention, is that the problem seems to be more frequent when the car has been unused for a while. Again, I'll provide more info on the engine later.

Thanks again.

Anonymous
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Anonymous's picture

So it is an 103.

Built in 01/1992

Anonymous
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Anonymous's picture
Engine Stalls for about 15 minutes then runs true

My Mercedes 400E has a very similar problem. It starts okay initially and runs okay for the first five to ten minutes. After that the engine bogs down and stalls unless I keep the RPM's above 1000. If I nurse it along for another ten minutes or so at stop lights, it eventually gets around to running smoothly and no longer stalls. Once it has warmed up, it does not stall at all. Leave it sit long enough to reach ambient temperature and again, it may or may not fail. It also seems to be more likely to stall if it has been sitting for a few days to a week. I too have had no luck with diagnosis from the dealer. Who can help?
Thanks, Rich

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