1992 E300 (automatic) engine keeps stalling

[tom9382]

Hey,

This problem keeps getting worse and I was wondering if any experts here may know what could be wrong. The description might be sorta long, but it's necessary to describe what happens, it's really awkward.

Here is how it happens:

In the morning (or any time the car has been standing for 10 or so hours), I turn on the engine and leave my house. After about 3-5 minutes I drive down a hill, and when I get off the gas pedal the RPM needle JUMPS to 0. The same thing happens when i get off the gas as I'm nearing a stop sign or traffic light. If i don't touch the gas pedal again and just brake, the engine will die once the car slows down. Sometimes I can prevent that by changing to 3rd or 2nd gear or just accelarating to try to get higher rpms. If the engine dies, I have to wait a few minutes for it to start again (if i'm lucky).

More recently, the problem has gotten worse. In addition to the above, sometimes, when I come to a complete stop the engine does NOT die, but when I want to accelerate from the complete stop it DOES. Also, the engine would start again almost immediately, but when I put it back in to Drive (or 2nd/3rd gear for that matter), the same happens. The engine dies as I hit the gas pedal.

Overall the car is in a very good condition. I get it serviced regularly. I also brought my car to the shop several times now, but they can never find the problem.

Here is some more info on my car. It's a 1992 E300 automatic, 6 cylinder gasoline powered. It has around 122,000 miles.

Lastly, 20-30 minutes after cold starting, the problem tends to go away.

Anyway, thanks for reading this, and I would GREATLY appreciate if someone could lead me in the right direction. It's become increasingle dangerous driving my car as I could get stuck in the middle of an intersection at any time.

Thanks

[Ali Ibrahim]

It could be the 'Over Voltage Protection Relay'. It is located behind the battery. You may try to replace that.

Thanks
Ali

[tom9382]

Originally Posted by Ali Ibrahim

It could be the 'Over Voltage Protection Relay'. It is located behind the battery. You may try to replace that.

Thanks
Ali

Thanks for the reply. Any specific reason as to why you think it is the 'over voltage protection relay'?

[Bruno_300TE]

First I'd check ignition, especially the distributor, rotor and coil. On my car (92 300TE), a random stalling, as if it was starving for fuel, turned out to be a bad rotor. The fuel pump relais might also give you such symptons (integrated in MAS unit for your car), I have read that on this forum quite a few times. Regarding the OVP, wouldn't the car still run in limp mode even with a bad OVP?
Good luck, Bruno

[Ali Ibrahim]

It's happened to me last time almost similar to you on my 1994 E220. After replacing OVP, it was back to normal.

Thanks.
Ali

[John Plut]

As you probably know, intermittent problems are the worst to troubleshoot.

Besides the OVP relay and ignition system, there are a couple more things that you can check out:

My '88 260e was hesitating very badly as the engine warmed up. The car started fine but as the temp gauge got to about 60 degrees C the car would stumble and almost die when accelerating. Once it reached normal operating temperature it ran fine again. As you said, it was dangerous to pull out into traffic. My problem turned out to the EHA valve on the back of the airflow sensor that enrichens the fuel mix at the car warms up. The part is easy to replace but not cheap (about $200). I replaced mine mainly because it had a slight fuel leak and after replacing it the hesitation problem was fixed.

The second possibility is the airflow sensor pot on the front of the throttle body. It is an electrical potentiometer attached to the throttle plate shaft that senses the throttle position. The pot wears out first at the idle position and an intermittent circuit failure can cause the engine to die. My car would die occasionally with no warning while idling or when coasting around a corner. Red lights would just appear on the dash. The problem got worse over the course of a couple months until I was afraid to drive the car.

Do a search on "airflow sensor pot" on this forum for more info. The dealer will want to install a new airflow sensor for big $ but I bought the pot separately for about $80 online from olyparts.com. It is a VERY sensitive part to replace and you must be careful to scribe alignment marks on the housing to get it back in the right position. I have heard of people having problems with corrosion on the pot that they successfully fixed by cleaning but mine was worn and not dirty and had to be replaced.

Good Luck!

[tom9382]

Thanks for all the replies, i really appreciate it. I gonna check out what you guys suggested.