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1987 650 SEL
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18 Posts
Discussion Starter #1 (Edited)
560SEL Stalls when warm rough idle "Not Solved"

Hello all

Im a student and this is my only transport so i gotta get this fixed.

i have searched the forums and read countless posting but im not getting results.

Here are the symptoms: (only happens when warm)
-rough idle
-cant keep running dies in park or neutral
-When in gear i have to press gas to keep it alive
NOTE: when i unplug the EHA valve the car runs (when warm and all the symptoms are happening, idles at 1000rpm)

What i have done so far.
-New plugs, Cap, rotor, wires (all MB parts)
-intake manifold cleaning
-Idle air valve cleaning and verified working
-Fuel pump and filter good
-coil is good
-vacume tubes are all good
-Vacume line all good
-FPR good


Any help would be wicked cause its driving me insane. This car has always been well maintained regardless.

Has anyone else had this problem? on other similar postings people have described this problem but never updated their findings.

Thanks
 

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Registered
1987 650 SEL
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18 Posts
Discussion Starter #3
here's something i thought was interesting

When the car is started from cold with the EHA valve connected, it will start and run fine. if i start the car from cold with the EHA valve unplugged it stutturs and then eventually starts and runs fine. when its revved it hessitates.

When the car is warm(hot) after driving for a while it dies at a stop (the symptoms described in first post) But if i unplug the EHA valve it runs fine with no hesitation

Am i on the right track?
 

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Registered
1993 300TE, 1995 E320 Wagon
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1,895 Posts
FPR is good-- according to whom? I'd say that it's the FPR that has an electrical issue when it gets warm. Not all that unusual. I had a bad FPR that would allow cold starts just fine, then would give all sorts of hesitation, stalls, hard restarts when warm. I'd test out another known good FPR.
 

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Registered
1987 650 SEL
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18 Posts
Discussion Starter #5
Im gonna try your suggestion as i have a spare relay. I will report back as soon as i can
 

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43 Posts
grumpy and I had same problem

This sounds like same problem that me and also a guy who called his car grumpy had. We both changed our fuel mixture control units and the problem went away. Now as far as pin-pointing the problem we did not. But changing the fuel mixture control units seemed to do the trick. Good luck.
 

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1987 650 SEL
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18 Posts
Discussion Starter #8
Installed a new FPR and everything is working good. Thanks for all your help gents
 

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Registered
1987 650 SEL
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18 Posts
Discussion Starter #9
Well im back to square 1, problem not solved

Im gonna check the potentionmeter next

Any other ideas guys?
 

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43 Posts
Listen to Grumpy and I

Try installing a different fuel mixture unit. I promise this will do the trick. Correct me if I'm wrong. You installed the FPR and started car and everything sounded good. You thought the problem was corrected until after the engine warmed. Then the problems continued. Here is another measure. After a cold start try flooring the accelerator. The engine should respond correctly. The minute the engine warms you will hear a difference in the engine. After the engine warms try flooring the accelerator again. This time when you floor it the engine will stumble over itself and will not give full acceleration. If this happens it is definitely the fuel mixture control unit.
 
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