300E runs rough on hot days - PeachParts Mercedes-Benz Forum

mike690003 · #1 09-21-2003, 01:58 PM

Hello Board,

As you all know, my 300E has ate up a lot of $$$ and it is still missing at idle. I have been feverishly attempting to pinpoint the culprit that is causing my 300e to run so rough. I have to suffer while driving in the daytime because if I turn my A/C on, my car will hestiate from the stoplight really badly, to the point of almost stalling. Well what I have come to realize is that it runs rough only in the hot daytime. When I drive at night the car idles a lot better, it does not miss at idle as much and the hesitation is not as bad. Well I have recently replaced my #5 and #6 fuel injector( the worst ones). I plan on doing the whole set next week.

I was wondering if the coolant temperature sensor could have an effect on this weird problem??

Any other suspected culprits??

Parts replaced:

Almost everything

ctaylor738 · #2 09-21-2003, 07:54 PM

My '86 with the same problem frustrated me to the point where I sold it. The new owner reports the car is running fine. At least you have a consistent problem.

IMHE, it could be any, some, or all of the following:

-vacuum leak
-idle control valve
-EHA
-air flow meter
-coil
-injectors
-injector seals
-fuel distributor
-plug wire or wires
-ECU
-temp sensor
-throttle position sensor
-throttle close microswitch
-OVP relay or fuse
-flakey wire or wiring harness

mike690003 · #3 09-22-2003, 02:58 PM

Anyone else had this problem in a car with the m103 motor??

If so, how did you fix it??