HELP! mystery problem w/ '92 Benz 400e


I have a problem with my 1992 Benz 400e and neither I nor my mechanic (who has been great servicing my previous car, an '88 BMW 325) seem to be able to figure out what is the cause…

It is an automatic transmission with something like 266,000 miles on it.

the symptoms:

The car can rev up in park/neutral and get the RPMs up to 4 - 5000 but once its in gear, there is a serious lack of power. It feels as though its stuck in a low gear and pulling some heavy load behind the car. Mind you, before this problem arose, this car could GO. Its a big V8 engine.

Going down hill or on flat, I can the speed up some, but it shifts very roughly and what feels lke late… as though the engine is struggling, struggling, struggling and then it finally clunks into the next gear.

Going uphill is another story. I can’t get the RPMs or the speed up at all.

there is another problem which only happens intermittently and that is that once in a while while driving, usually when taking off from a stop, the engine sputters and gurgles and loses almost all power. When this happens I pull over, turn the engine off, let it sit for a moment. Usually when I start it back up, it goes and suffers only from the first problem.

I checked and topped off transmission fluid - that didn’t do anything.

My mechanic said he ruled out transmission, exhaust and timing. He thought he had it narrowed down to the mass air flow sensor and was pretty confident that that would solve the problem. He replaced that part but it didn’t solve the problem.

I have 3 questions:

1. Does anyone on this message board have any idea what else could be the source of this problem?

2. How long do I leave the car with my mechanic as opposed to taking it elsewhere?

3. Should I expect to be billed for all of his trial-and-error in a so far unsuccessful attempt to diagnose the problem?

thanks in advance.


Does it have the original converter on it?


Catalytic converter? I don’t know, but I suspect so. Why? Could that be part of the problem?


This sounds more like an engine issue than a transmission issue to me. This may be a case where it makes sense to go to the dealer if you don’t have a good shop that specializes in benz. It is much too expensive to just throw parts at these cars. If your guy doesn’t know what the problem is, ask him if he thinks it needs to go to the dealer. If he performed the “trial and error” diagnosis with your approval, you should pay him for his time and parts.