N54 Engine stumbles on start. Crank is fine.

blau808 · 03-28-2016, 08:32 PM

This doesn't happen on every startup, but occasionally after the crank catches (no long crank issues), my engine sounds like its struggling for a few seconds before sounding normal. Here's the thing, I had my HPFP and injectors replaced along with my battery, but still occasionally have this issue.

From what I've read here (and it was a lot of reading), injectors or the HPFP would be the main culprit, but that doesn't seem to be the case with me. Anyone have any other ideas? My car does not throw up any codes.

autoAER · 03-29-2016, 04:23 PM

injectors are the likely cause. if the stumbling issue clears up after a few seconds (rough idle clears up) i would just replace the injectors, as i had the same issue and new injectors fixed it right up.

AM330i · 03-29-2016, 11:33 PM

When did you have the injectors replaced? It does sound like a leaky injector. I had 2 leaking and it started rough but cleared up after a few seconds. New injectors took care of the issue. Also when was the last time the spark plugs replaced. Worn plugs could also cause this.

casp3r9 · 03-30-2016, 12:09 PM

Any oil leaks? Check around the edges of the valve cover with a mirror. A valve cover gasket can attribute to this but the more likely culprit is plugs, injectors and carbon deposits on your intake valves. I have experienced issues with all four - none of which threw a code.

BKBMW335I · 03-30-2016, 01:31 PM

Quote:

Originally Posted by blau808

This doesn't happen on every startup, but occasionally after the crank catches (no long crank issues), my engine sounds like its struggling for a few seconds before sounding normal. Here's the thing, I had my HPFP and injectors replaced along with my battery, but still occasionally have this issue.

From what I've read here (and it was a lot of reading), injectors or the HPFP would be the main culprit, but that doesn't seem to be the case with me. Anyone have any other ideas? My car does not throw up any codes.

sounds like an 02 Sensor issue.

03-28-2016, 08:32 PM	#1
blau808 Second Lieutenant 91 Rep 254 Posts Drives: E90 F31 X5 Join Date: Dec 2012 Location: PNW iTrader: (0)	N54 Engine stumbles on start. Crank is fine. This doesn't happen on every startup, but occasionally after the crank catches (no long crank issues), my engine sounds like its struggling for a few seconds before sounding normal. Here's the thing, I had my HPFP and injectors replaced along with my battery, but still occasionally have this issue. From what I've read here (and it was a lot of reading), injectors or the HPFP would be the main culprit, but that doesn't seem to be the case with me. Anyone have any other ideas? My car does not throw up any codes.
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03-29-2016, 04:23 PM	#2
autoAER Private First Class 51 Rep 107 Posts Drives: Monaco Blue 335i Join Date: Jun 2014 Location: Concord, CA iTrader: (0) Garage List 2011 BMW 328i [0.00] 2006 BMW 330i [5.50]	injectors are the likely cause. if the stumbling issue clears up after a few seconds (rough idle clears up) i would just replace the injectors, as i had the same issue and new injectors fixed it right up. __________________ Current: 2006 330i Mystic Blue 6MT, 2011 328i Coupe Titan Silver Ex: 2006 330i Barrique Red, 2008 335i Monaco Blue, 2011 335i Deep Sea Blue
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03-29-2016, 11:33 PM	#3
AM330i First Lieutenant 90 Rep 386 Posts Drives: 08 535xi 11 328xi Join Date: Oct 2011 Location: Rochester, NY iTrader: (0) Garage List 2023 BMW M440 [0.00]	When did you have the injectors replaced? It does sound like a leaky injector. I had 2 leaking and it started rough but cleared up after a few seconds. New injectors took care of the issue. Also when was the last time the spark plugs replaced. Worn plugs could also cause this.
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03-30-2016, 12:09 PM	#4
casp3r9 New Member 0 Rep 9 Posts Drives: E82 135i N54 6MT Join Date: Sep 2015 Location: Los Angeles iTrader: (0)	Any oil leaks? Check around the edges of the valve cover with a mirror. A valve cover gasket can attribute to this but the more likely culprit is plugs, injectors and carbon deposits on your intake valves. I have experienced issues with all four - none of which threw a code.
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