Hi All. I just picked up a 1989 300E I intend on using as my daily driver. It has been sitting since late 2008 when the previous owner decided he was getting too old to drive. I drained the old gas, etc... I have a few 300E's for parts in my back yard, so I thought I couldn't go wrong since I have all the parts I would ever need at hand. I'm used to working on W107's and W126's, so I am kinda unfamilliar with this issue on the W124.
Anyway, I have a major stalling issue with the car. I have done everything so far. I replaced the fuel filter, replaced the air flow sensor AND the fuel distributor, EHA valve and some related components in the area. I also swapped out the computer with a known good one, and no difference. Both fuel pumps are running fine. I also have good spark. I get about 12.5 volts measured from both sides of the coil.
Now for what happened before I got the car: someone got underneath it and stole the catalytic converter. But they cut it off after the Y , just before the resonator. The 02 sensor is still there.
I replaced the exhaust and just put a straight pipe in place of the cat. Could this have something to do with it?
The car will idle 100% smooth, and when pressing the accelerator in either park or N it will rev smoothly without wanting to stall. When in drive it seems to want to stall when I come to a stop, go around a corner or am driving on an unlevel surface.
My main question is what is the voltage supposed to read at the EHA valve? I'm getting about 4 volts at idle, and I'm also getting about the same at the idle valve. Does anybody have any schematics or diagrams with what voltage should be read in this area that could be emailed to me?
Any suggestions on what to do next? Anyone having similar problems? I'm pulling my hair out and everything I swap out does not make a difference.
Thanks!

I have doubts that someone pulling a hackjob on your exhaust system caused the problem, have you changed the spark plugs etc? the correct type? not sure, but if your engine has a CPS (Crank position Sensor) I'd take a look at that too, not sure if your engine has that however

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hum.....
1987 300TD 311,000M Stolen. Presumed destroyed

Ken, inspect the condition of the spark plugs, distributor cap terminals and distributor rotor. Replace as required.

Replacing the Oxygen sensor may resolve the hesitation/stumbling problem. I have had success doing that in one of our 124 automobiles.

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Fred Hoelzle

Swap the OVP with another good one just to rule that out as well...

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

I swapped out the OVP relay and no difference. Crank position sensor is also OK. It's reading with the VOM was within spec. The entire ingition system is new. New wires, plugs, rotor and cap. One thing I did note was after about 3 miles of driving, the plugs were fouled with carbon. The car has no issues idling or revving in park or neutral, and I can even hold on the brake in drive and floor it and the car wont stall. It only stalls when moving, especially when I come to a stop, or pull it into my driveway, which is on an angle. Is there any chance I could have a bad fuel accumulator? Are fuel accumulators prone to clogging? As I said earlier, the car has sat since 2008-2009.

I pulled out the fuel pumps, and sure enough one of the fuel pumps was seized up. So, Luckily I had a spare and hope to have it back together tomorrow. I'm keeping my fingers crossed so I can start driving it!! I've always loved the 300 series and while its not as comfy as as my W126, or as fast as my W107, I still love it! I've had a few W124's and have never had any complaints about them. Hopefully replacing this bad pump gets it back on the road again and I can break it in on a nice long drive playing a good Grateful Dead show (or two)


"once in a while you get what you like in the strangest of places if you look for it right"
-Jerry Garcia "Scarlet Begonias"

OK. TIME TO PULL OUT MY HAIR....
Changed the fuel pumps and filter AGAIN and it ran and drove down my street, but on the way back it started acting just like it did.
What now? What AM I missing? I need help

connect the fuel pump relay pins directly for a test run ,its possible the seized pump caused problem in that relay wiring.

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mark

Fuel pump 1 was seized!!! Thanks for the suggestion, Mark!!

I want to thank everyone who helped me out on this. I finally got it up and running beautiful. Here is what I did after everything I listed I did above. First, I pulled out all injectors, cleaned and tested them then replaced the seals. Next, I pulled the the airflow meter off and cleaned that, then removed the throttle body and did a thorough cleaning. Put it back together, and I still had the stalling issue, but it was much better than it was. I noticed that the fuel pumps were pulling way more current than they should, so I pulled them, and found one was seized up. So I replaced both pumps and my fuel filter, and now the car is running 100%. In hindsight, if I would have checked the pumps first, I would have saved myself a ton of time, and not be missing as much hair LOL! Anyway, thanks all for everyone who offered suggestions and took time to help me!!

Now, I found another 300E locally, and quite reasonably priced, with similar issues. Question is, should I buy it? I could always use another nice W124!!

i am having the same trouble. lucky this post is at top.

89 300E.

runs fine when car is cold idling, but when at operating temperature, it will stall if accelerator is pressed too fast.

duty cycle is reading 0% so I figure I am going to start there, but I have to ask, how much current should the fuel pump be pulling?

Hi John, I don't know how much current your FP shoudl be pulling so I'm sorry if I can't answer that question. However, I would recommend that you change out the fuel filter if it hasn't been done recently as your issues are consistent with a clogged fuel filter, and it is normal maintenance.

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TC
Current stable:
- 2004 Mazda RALLYWANKEL
- 2007 Saturn sky redline
- 2004 Explorer...under surgery.

Past: 135i, GTI, 300E, 300SD, 300SD, Stealth

I haven't done it so I will. However, i dont think thats the problem though.

the car will hit all the revs before operating temperature. once I reach around 87C, the idle goes rough and stalls if I punch the accelerator too fast. all spark plugs are firing (but not sure if misfire, checked with timing light).

will do some more checking tomorrow.

Well I fixed my problem.

It was the fuel filter and a bad EHA. replaced both and now the car is happy.