I did the right thing and did a search on "rough idle" since my 400E is idles rough when cold. One of the suggestions, which worked for a 500E owner, was to run a couple bottles of BG 44K through the fuel system. This apparently worked when Techron didn't. I've searched the web and my local stores and can't find someone who sells BG products. Does anyone have an internet or other source for this product?

Thanks!

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Steve
'93 400E

Try this link, http://www.bgprod.com/locator.html.

Thanks, Ross. Just met with my local BG rep, found via that website. Now I just need to wait till my gas tank is low so I can try the stuff at the next fill up!

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Steve
'93 400E

Have you tried BG 44K? Did it solve the rough idle problem?

My 92 400E does exactly the same thing right now, it has been idling roughly after cold start since this winter, now it's getting worse, however I don't feel the problem when engine warms up.

Can you let me the result?

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99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.

Howdy,
Yep, I tried 2 consecutive tankfuls of it. It didn't seem to help the idling problem, unfortunately, but it seemed to give a little better throttle response (or it could be just my imagination).

I've heard that the fuel pressure regulator can cause idle problems in the 119 engine and have been thinking about replacing mine.

I also wonder about the role of collapsed motor mounts, since I've been reading a lot lately about how they often are shot in our engines after about 60 k miles, and can make a little idle shake more noticeable.

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Steve
'93 400E

Thank you for the response,

I have replaced fuel pressure regulator, plugs, caps and rotors 4 months ago, it didn't help, also plan to replace motor mount when spring comes.

My idle problem was very erratic when cold, it sometimes can surge +300 rpm, so new motor mount can't help either. From the post in this forum, I feel M119s are very prone to unstable idle. I also plan to replace timing chain, fuel line and fuel filter, will let you know if it helps.

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99 BMW 540i 6-speed 110K Km
03 SAAB 9-5 wagon 80K Km
92 400E (Sold) 245K km
Still missing the days with the Benz, it kept me busy.

Thanks for the info!

I had replaced my caps/rotors last year and like you, no help.

I am starting to think you're right, that it's inherent in the breed. I bought my 400E when it was a young pup, 3 years old and 25,000 miles, coming off someone else's lease. I remember taking it in right after I bought it, and complaining of this very same idle. "That's just the way the V8s are" was the response. At the time I thought it was hogwash, since I figured the more cylinders, the smoother the idle.

I have no other engine-related problems -- mileage is good (20/25), starts quickly in all weather, good acceleration -- so yep, maybe "They all do that". . .

I will be VERY interested in your timing chain experiences. I am really torn about what to do. I surely don't want to spend thousands of $ for damage related to chain breakage, but my tech says "Leave it alone until it gets noisy" and so does Stu Ritter, who owns a 400E. I hear there's a lot of labor involved to get to it and the rails.

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Steve
'93 400E