320i

amorak · 09-25-2014, 02:58 PM

Hey guys,

Does anyone have any thoughts on the video I've attached to this post? My 320 has a bit of a stumble three or four times on every cold start. I have a JB4 on it and I don't recall if this was happening before I put it on. I don't think it was?

Hopefully the video is decent. It's only a few hundred rpm stumble that you can feel and hear.

ft1330 · 09-25-2014, 03:01 PM

I have a kind of stumble on my 335i (stock) when taking off at slow speed after a cold start. It's just (1) small RPM fluctuation. But not when idle.

Austinformedude · 09-25-2014, 08:43 PM

Welcome to CAFE standards. When the catalytic converter and car is cold it runs a different program so as to limit pollution. It runs so lean it almost can't run at all, and it is a fine line. It takes the system a bit to level out.

xDrive35i · 09-26-2014, 12:38 PM

My X3 used to do that when new. It went away.

Labeef · 09-28-2014, 04:57 PM

It's most likely the secondary air pump that pumps for the first 30 seconds. Looks like a non-issue.

09-25-2014, 02:58 PM	#1
amorak New Member 6 Rep 17 Posts Drives: 2013 F30 320i xDrive Join Date: Jan 2009 Location: Calgary, AB iTrader: (0)	320i - idle stumbles on cold start Hey guys, Does anyone have any thoughts on the video I've attached to this post? My 320 has a bit of a stumble three or four times on every cold start. I have a JB4 on it and I don't recall if this was happening before I put it on. I don't think it was? Hopefully the video is decent. It's only a few hundred rpm stumble that you can feel and hear.
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09-25-2014, 03:01 PM	#2
ft1330 Major 231 Rep 1,267 Posts Drives: 2014 335i Join Date: Oct 2013 Location: SE PA iTrader: (0)	I have a kind of stumble on my 335i (stock) when taking off at slow speed after a cold start. It's just (1) small RPM fluctuation. But not when idle.
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09-25-2014, 08:43 PM	#3
Austinformedude Private 10 Rep 54 Posts Drives: 2013 328 Join Date: May 2014 Location: Austin, TX iTrader: (0)	Welcome to CAFE standards. When the catalytic converter and car is cold it runs a different program so as to limit pollution. It runs so lean it almost can't run at all, and it is a fine line. It takes the system a bit to level out.
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09-26-2014, 12:38 PM	#4
xDrive35i Lieutenant Colonel 126 Rep 1,781 Posts Drives: Porsche Macan S Join Date: Feb 2011 Location: Chicago iTrader: (0)	My X3 used to do that when new. It went away.
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09-28-2014, 04:57 PM	#5
Labeef Captain 265 Rep 807 Posts Drives: 320I Sport/Xenon Join Date: Jul 2014 Location: Bay Area, CA iTrader: (0)	It's most likely the secondary air pump that pumps for the first 30 seconds. Looks like a non-issue.
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