Unofficialbmw.com

[Power1]

Need some input re. my 94 740il that idles very rough when the weather and/or engine is cold. The problem seems to virtually disapear in hot weather.

A year ago, I had several items (including oxygen sensors and some gaskets) replaced in an attempt to fix the problem. Nothing helped, and the mechanic (a German car specialist) suggested having the EPROM chip replace by a dealer. There is BMW bulletin re this chip. Had that done and situation improved slightly, but is still a problem.

Apparently the engine is running rich when idling--which produces the roughness and vibration. My friends are starting to call it my Beemer truck!

I've also heard some suggestion that this is a common problem with certain BMW engines that used some sort of Teflon (?) coating. Apparently the coating deteriorates, resulting in various leaks in the engine block that interfere sufficiently with the carburation to cause the engine to run rough.

Any ideas or info about this??

[PJK]

There was a problem with some V8 engines. BMW uses a plating process on the cylinder wall to give a hard surface. There was a problem with the first process they used and our fuel in the USA. They changed the process and replaced engines which failed before 100 k miles. The old and new process is identified in the S.N. of the block.(under the engine and a pain to get to)I wish I could remember all the details but you can probably can find them on the internet. I would incourage you to persue this before 100 k miles considering the price of that engine.

On the good news side, your engines idles OK when it is warm. Hard to imagine piston ring to cylinder sealing problems which are temperature sensitive.
Are you getting oil smoke? That would be smelly white smoke. If your engine is running rich you should see black smoke.

I think you have a bad temperature sensor.(coolant temperature or intake air)

In any case make sure you have the good block before the 100 mile thing is over.

My wife bought a '93 740i which had the engine replaced for the cylinder problem.

I did crawl under the car to check the SN.
She now has the good engine.

I will try to find the literature I used and e-mail the URL of the site if I find it.

Good Luck,

Phil

quote:

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Originally posted by Power1:
Need some input re. my 94 740il that idles very rough when the weather and/or engine is cold. The problem seems to virtually disapear in hot weather.

A year ago, I had several items (including oxygen sensors and some gaskets) replaced in an attempt to fix the problem. Nothing helped, and the mechanic (a German car specialist) suggested having the EPROM chip replace by a dealer. There is BMW bulletin re this chip. Had that done and situation improved slightly, but is still a problem.

Apparently the engine is running rich when idling--which produces the roughness and vibration. My friends are starting to call it my Beemer truck!

I've also heard some suggestion that this is a common problem with certain BMW engines that used some sort of Teflon (?) coating. Apparently the coating deteriorates, resulting in various leaks in the engine block that interfere sufficiently with the carburation to cause the engine to run rough.

Any ideas or info about this??

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[This message has been edited by PJK (edited 01-25-2002).]

[PJK]

Sorry I haven't found it yet. I know that I downloaded it from someones website. I' keep looking.

Phil

[PJK]

quote:

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Originally posted by PJK:
Sorry I haven't found it yet. I know that I downloaded it from someones website. I' keep looking.

Phil

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Here it is. Chapter and verse on the V8 problem.
Look for most requested pages. - M60 engine

Good luck,

Phil
http://www.koalamotorsport.com/default.htm


[This message has been edited by PJK (edited 01-29-2002).]

[This message has been edited by PJK (edited 01-29-2002).]