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faulty ECU?

2K views 11 replies 6 participants last post by  w124uk 
#1 ·
I'm desperate to solve the uneven idle when engine gets warm. Thought it might be the oxygen sensor, replaced but no luck. Just to let you know I've checked (and/or replaced the following):
Spark plugs (new)
HT leads (new)
distributor cap
rotor arm
fuel filter (new)
lamba sond = oxygen sensor (new)
chekced the injector seals
injector cleaner (3 bottles)
and probably a couple of other minor things

Now I'm running out of ideas...could it be the ECU? I had no idea the car can actually run with the ecu disconnected (runs rougher than usual but I did have it running with the disconnected Jetronic ECU in my hand!). Do you know if the ECU is likely to pack up?
Hope to get it fixed....hope you can help!:confused:
 
#5 ·
Was the idle un-even before you replaced the OVP? You might also try spraying some WD-40 at the injectors (O-rings) and all vacuum connections. If you notice an increase in RPM at any point along the way, you will have found the problem.

Good Luck,

Jayare
 
#8 ·
uneven idle

I have just had a problem which I solved on an old 230TE. Would start from cold fine, idled smooth then would start to vary in idle, with some rich smoke and eventually die. Checked everything including removing and cleaning fuel filter/checked for vacuum leaks, problem still persisted. Found the fault by accident as I was checking for leaks. It was the head temp sensor connector that was duff and not making good contact with the sensor. Re-terminated same and now engine runs smoothly again.
 
#9 ·
That was another of my guesses, looks like I have a 4 pin temp sensor (apart from the 1 pin for the gauge on the dashboard of course)..tried to get a pattern part but looks like I'd have to get a genuine Mercedes one... need to check the price first...
 
#10 ·
w124uk said:
One more thing I noticed - when I disconnect the oxygen sensor (same story with both the new and the old one) the car ticks over nicely but uses way more fuel....
I don't have an answer for your rough idle right now, but when i replaced my O2 sensor with the Ford one I noticed a spike in fuel consumption for a couple tanks of gas. After that I went back to normal, maybe a little better.

Hope you can find a solution!
 
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