Could be crankshalt sensor,that it screws up when it gets hot,also a big possability a coolant temp sensor. .

so the things so far i know its not...
coil
transmission
02 sensor
KE unit
plug wires
things it still could be
ignition module
still haven't checked the cap and rotor
cats?
vacuum leak
crank sensor

__________________
E30 B25
126.036
123.130 with 616-Frankenbenz (sold)
124.030-Greyhound (sold)
124.030-Schnauzer (sold)

DERP DERP

interesting, cap and rotor would have been the first thing I would have checked just because you can and it's fairly easy.

When were they done last?


Jonathan

__________________
Blue Ridge Mercedes
Jonathan Hodgman
http://www.blueridgemb.com/
Enthusiast Service, Restoration & Tuning.
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Located in the Atlanta area
Specializing in all pre and post merger AMG's including Hammers and DOHC M117 engines.
Mercedes Repair Atlanta

Again....make sure your gas tank is venting.

My 560 front cat partially disintergated and rotated in its housing blocking gas blow. Systoms are different from yours. Highway is tough because the gases can't get through the blockage. stop and go was fine acceleration was gone. No back fireing or stuttering. Just no top end.

the reason i have delayed in checking it is it was done less than 3k ago about 6 months, and the problem didnt start until recently, but its next on my list over the weekend. how do i check the fuel tank vent? thats what i was wondering about on the cat, so maybe i can cross that off the list since the car passed emissions with flying colors when i got it and that sort of thing doesnt just happen all of a sudden does it? next stop, cap and rotor

__________________
E30 B25
126.036
123.130 with 616-Frankenbenz (sold)
124.030-Greyhound (sold)
124.030-Schnauzer (sold)

DERP DERP

Try this: Unplug the EHA and see if the problem persists. If the problem goes away, that eliminates spark issues and the mechanical part of the FI.

My daughters '87 300E had random bog and rich running issues. It's running fine w/o the EHA plugged in. Now to find the time to chase what's actually causing this.

unplugged the EHA and no difference, took the cap and rotor off and this could very well be the problem, theres some green stuff around the edges, and sure enough when i looked back behind the orange o ring i saw another black o ring that had hardened... any thoughts?

__________________
E30 B25
126.036
123.130 with 616-Frankenbenz (sold)
124.030-Greyhound (sold)
124.030-Schnauzer (sold)

DERP DERP

Sounds exactly like what I had. It looks like we both made the same mistake when replacing the cap and rotor. There should be one o-ring around the base of the "backing plate" (where you found the black one). I had installed the new orange o-ring and left the old, black one in place which apparently caused improper clearance inside the cap. I put new parts in and so far it runs great.
Chuck.

im awaiting the parts now, so much for 3 day shipping... the main thing is how long after you installed these parts did the problem start?? hopefully this will resolve a problem that has basically made the car un-drive able.

__________________
E30 B25
126.036
123.130 with 616-Frankenbenz (sold)
124.030-Greyhound (sold)
124.030-Schnauzer (sold)

DERP DERP

It took about 8-10K miles after the new cap and rotor for the problem to show up. It got worse over the next several hundred miles (I kept driving it-see thread). I guess it took that long for the internal arcing to degrade the function of the contacts inside the cap. I had lots of green crud around the terminals and the center post inside the cap was charred and crumbly. I bet you've found your problem. What threw me off was the different color and appearance of the new o-ring that I ordered. I now realize that it was the same dimensions as the black one and was supposed to replace, not supplement the black one.
Chuck.