# 535d Stumble



## aherman535 (Nov 11, 2007)

2015 5353d with about 10k. For last couple of weeks, a few moments after starting, the engine stumbles for about 3 seconds and then runs fine. 

Reminds a big of the N54 fuel pump issue.

Anyone else seen this on their diesel?

Thanks,

Andrew


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## John Galt (Jul 21, 2012)

Here is the answer you seek:

http://www.bimmerfest.com/forums/showthread.php?t=871768

You have CBU. Get it in to have a thorough cleaning, and prepare for a multi-week out-of-service. BMW should either get these diesels fixed properly to run on our percent-content biodiesel or stop selling them here!

-John


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## ingenieur (Dec 26, 2006)

A slight stumble after cold start is normal - no way it is CBU. I have felt a slight roughness once ot twice if I just let it idle and do not drive away as usual. 
The ISTA test plans now can check for CBU which is sufficient enough to cause a driveability issue or faults.
Only known N57 issue has been HP EGR cooler sooting on the F15 in some instances - but that is now addressed with a DDE software change.


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## aherman535 (Nov 11, 2007)

Only got 11k, although I lot of short trips. Should I try one of the diesel additives?


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## John Galt (Jul 21, 2012)

aherman535 said:


> Only got 11k, although I lot of short trips. Should I try one of the diesel additives?


Did you read my thread I linked? If you have these "stumbles" after the vehicle has been driven (even a few miles) then "heat soaked" as in sat in the hot sun, you DO have CBU. If you're experiencing a shudder after a warm start, ingenieur has a 328d and doesn't know what he's/they're talking about as it relates to our 6 cylinder engines. If it is after a cold start, he/they are correct in that our d's will slightly shudder a little on warm-up (which diesels as you know, never really warm up as gas engines do unless under load). And for the record, my new (as of Oct 15) X5 35d experienced CBU at just over 18,000 miles. You're within range.


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## d geek (Nov 26, 2008)

John Galt said:


> Did you read my thread I linked? If you have these "stumbles" after the vehicle has been driven (even a few miles) then "heat soaked" as in sat in the hot sun, you DO have CBU. If you're experiencing a shudder after a warm start, ingenieur has a 328d and doesn't know what he's/they're talking about as it relates to our 6 cylinder engines. If it is after a cold start, he/they are correct in that our d's will slightly shudder a little on warm-up (which diesels as you know, never really warm up as gas engines do unless under load). And for the record, my new (as of Oct 15) X5 35d experienced CBU at just over 18,000 miles. You're within range.


I think it's a bit over the top to be so sure that it is CBU. Especially if it runs fine. I'd not be concerned unless it gets worse.

And you can tone down the "he doesn't know what he's talking about" stuff just because someone doesn't have the same engine as yours.


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## aherman535 (Nov 11, 2007)

Actually the problem is first start in the morning. Then runs fine all day. It is like it almost stalls, then catches and all is good.

Thanks for the suggestions.


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## ingenieur (Dec 26, 2006)

d geek said:


> And you can tone down the "he doesn't know what he's talking about" stuff just because someone doesn't have the same engine as yours.


Thanks - my BMW diesel experience (4, 6, and early 8 cylinder) is certainly at a higher level than most and I'm more than willing to share with those who ask intelligent questions.


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## n1das (Jul 22, 2013)

aherman535 said:


> 2015 5353d with about 10k. For last couple of weeks, a few moments after starting, the engine stumbles for about 3 seconds and then runs fine.
> 
> Reminds a big of the N54 fuel pump issue.
> 
> ...


2014 535d Xdrive here, took delivery in August 2013. At 73k miles now, zero stumble following a cold start, even in below zero temps in the dead of winter.

This makes me wonder if there is an air leak in the fuel system and causing it to lose prime after sitting for a while. The stumble you describe sounds like it's fuel starved and about to stall but ran long enough to get re-primed again. It may be worth checking all fuel connections from the tank to the engine. Might be a dead or dying in-tank pump.

Dunno.

Good luck.


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## aherman535 (Nov 11, 2007)

n1das said:


> 2014 535d Xdrive here, took delivery in August 2013. At 73k miles now, zero stumble following a cold start, even in below zero temps in the dead of winter.
> 
> This makes me wonder if there is an air leak in the fuel system and causing it to lose prime after sitting for a while. The stumble you describe sounds like it's fuel starved and about to stall but ran long enough to get re-primed again. It may be worth checking all fuel connections from the tank to the engine. Might be a dead or dying in-tank pump.
> 
> ...


Could be the pump or a leak.

Worth checking.

Thanks


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## NWSnowboarder (Aug 30, 2015)

*Glow Plug*

Ummm, I think you guys are over thinking it.

Sounds more like a bad glow plug or glow plug relay. Both easily fixed.


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