stalling after the engine warmed up - PeachParts Mercedes-Benz Forum

300e · #1 08-12-2002, 02:31 AM

I have a 1988 300E, California model. Recently, the engine light came intermittently after the engine is at operating temperature.
The idle was hunting (surges and hesitations when idling and driving) and the engine eventually stalled. When cruising on the highway, the RPM fluctuating as the engine stalled and restarted.

Replacing the Oxygen sensor, over-voltage relay did not resolve the problem. Suspecting problem in the fuel delivery system. Please advise if you have come across this problem.

maximus · #2 08-12-2002, 08:24 AM

I had the same problem with my 89 300e and I also replaced the 0 sensor and the ovp but turns out to be my engine temp sensor , my eha was also leaking but i think in my case it was the EHA hope that helps a little

joe p · #3 08-12-2002, 08:40 AM

Does it lose fire? I had one that kinda kicked a few peoples butt that had a crank sensor going open when it got good and hot. It would shut down like the key was turned off, once it cooled a few moments, it would fire right up and run again. Driving it with a scope on it found it.

Check the cap and rotor as well, the rotots will burn though and fire directly to the adaptor on the end of the cam.

Joe

300e · #4 08-12-2002, 01:05 PM

Thanks, gents.

That was helpful.

Maximus,

I think that your problem quite similar to mine. I did not mention in the last post that I also replace the EHA which was leaking. In fact, I am replacing the temp. sensor (for the emission system) next.

When the engine warmed up, I checked the mixture reading (pin3 at the diagnostic socket) and it was not stable. I could not set the mixture to 6.5v DC and ECU kept compensating to 12 or higher even though I tried to turn the set screw clock-wise (rich). Under normal situation, the reading on my meter should drop when I turned clock wire.

Joe,

I have checked and cleaned the Cap, rotor, and plugs. They are all fine. that was the first thing I did as the symptom was quite similar to ignition problem.

Do you think that the fuel pump relay can cause this unusual problem?

mbe32094 · #5 08-12-2002, 02:36 PM

Does your car has mass air flow sensor?
I had the same problem you have. I found out the cause was the air floww sensor.
Check this thread.
http://www.peachparts.com/shopforum/showthread.php?postid=250206#post250206

joe p · #6 08-13-2002, 07:44 AM

Measure the lambda in duty cycle, onces it warmed up and out of open loop, set it about 40 to 50% it will cycle about 10% either side of center.

Joe

joe p · #7 08-13-2002, 07:47 AM

One more thing, clean that ISC valve on the intake. Located in front of the a/f sensor bolted to the intake. Check the hoses to and from it for craking as well.

Joe