1993 400E hesitation and stalling - PeachParts Mercedes-Benz Forum

Jhoulihan · #1 11-13-2006, 11:20 PM

My 400E has suddenly started to exhibit some strange behavior.
The car was running perfectly until a couple weeks ago when I started it up and it immediately began running roughly. If I suddenly press the gas pedal to the floor, the car will stall. If I put the pedal about halfway down, the car hesitates severely and then will accelerate normally.

This is not in itself very strange I guess but I have discovered that if I turn the car off and restart it 2 or 3 times, I can get it to perform normally. I can now tell by the way the car initially starts....if it runs rough upon starting then I just turn it off and restart until I get a smooth start and then it will run fine.

Can anyone suggest what might be causing this issue?

I'm thinking it might be a wiring harness issue but might I just have a bad fuel pump relay or filters or wires or plugs?

The car has 100K on the clock with 2 year old caps, rotors and plugs (20K on these). Original wiring harness and original plug wires.

Any help appreciated.

mbdoc · #2 11-14-2006, 08:04 AM

Take a close look at the distributor caps again. If they look good then the wires are the most likely problem.

hackbite7 · #3 11-15-2006, 03:10 AM

I'm running a 93 400E also, I've experienced similar problems. I would strongly recommend replacing the upper engine harness first . You won't beleve how much deterioration has occured with the engine heat in that engine compartment.

It's a DIY job, I started at the CAN and replaced the new one as the old one was removed. You'll be surprised at the amount of degraded wiring that's living in there. It sure can cause numerous running discrepancies.Definitely do the harness.Good luck.

ScotzBenz · #4 11-15-2006, 02:02 PM

Jhoul.. had very similar symptoms with my '92 400E last eaqrly winter. Based on problems my mother had had with her Nissan in the past, and the fact that I had within the past six months switched to the exact same driving habits as her:

The type of driving is as follows: winter, relatively high humidity, lots of quick (1-3 mile) trips, with a maximum distance on any trip of about 10 miles = Engine never really had the opportunity to heat up.

While I use quality premium fuel, I thought that several months of this type of driving cannot be good, so when at my local Chevron station purchased a couple bottles of techron. I let the fuel run down to about a third of a tank and put one in the tank.

I then made a point of taking the car for a "trip" through some mountain passes when I knew that the engine would be under a good load, and under load at a higher operating temperature.

After some time I did get some pretty good puffs of dark exhaust, when shifting down to passing gear headed uphill, which could be from various sources including the high concentration of techron in my fuel.

Following this, I've made a point of putting some techron in a low tank every couple of months, and the problem has all but evaporated. Certainly worth a try....my $8.42cents worth.....Scott

ScotzBenz · #5 11-15-2006, 02:24 PM

Jhoul,

Forgot to mention, changed my fuel filter during this recovery period as well....Scott

Jhoulihan · #6 11-16-2006, 12:01 PM

Thanks for all the suggestions. I have been avoiding replacing the wiring harness but yes, when I bought the car I did cut open part of the harness and see severly cracked insulation. I guess I'm surprised it has lasted this long. Anyone know a good source for a new one?

How about the plug wires? What brand is a good replacement and how about a good place to buy these?

Thanks again.