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Engine oscilation !!!


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I´ve a little problem with my ´95 eldo...

If the engine is on and the car are not rolling, the engine run with 800 UPM very nice...

If I drive and press strange the accelerator pedal the engine run very nice...

If I drive with low power (straight road or downhill or before I stop) the engine oscilate from 2000 UPM to 1900 UPM (for example). I can feel these oscilation.

These problem is from 0 to 3000 RPM and not at every time. I think it´s 20 % from the drive from 0 to 3000 RPM at the last 80 % the engine run very nice.

An I´ve I drive withou pressing the accelerator pedal (downhill etc.) the problem is the same.

If I drive in higher RPM (over 3500) the engine run very nice.

Now, I´ve cleaning the EGR valve and the problem is the same.

No error codes.

Engine and car has 30.000 mls.

What is it ???????

Thank you very much.

With best wishes from germany.


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Frank, I want to be able to help you but I need some clarification. Explain what you mean by oscilation for me, try to explain what you mean in more detail..

I have a friend from Germany that I work with, describe the problem in detail in German and I will ask him to translate for me.. I think that may help. Thanks, Mike

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Sounds like surging. I'm thinking fuel pressure problem - if your car was an 86 Chevy, I'd be pretty confident in saying it needs a fuel pump.

I'll be interested to see what the great minds here come up with........

Jack, Frank posted this same problem here back in December 2004, and we have now been successful with his problem.

Here is a link to that thread, Mike


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I thought this sounded familiar - particularly the part about it going very nicely when you push on the gas :D

Looks like you went down the EGR path before but it didn't fix it.

Have I missed something? What was the fix?

It has not been fixed yet, but I like you surmise surging. But what I am not sure is if he is describing surging or misfiring. His description of surging does not sound serious he says 1900 to 2000 RPM I think, that does not sound bad... This may be a stretch, but he may need a tune up, and he is feeling the AC compressor cycling. OR, he is having a problem with his CAT... I am hoping to get a good description of what the problem is.. Fuel filter is a good possibility..

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