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Need help diagnosing a surging issue
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07-06-2015, 07:59 AM | #1 |
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Need help diagnosing a surging issue
So...this morning I woke up for work and as I was backing the car out of my garage (cold start, about 71F or 22C) it started surging a little. I drive a recently acquired 2006 BMW E90 330i with 110K on the clock. This issue has never occurred before in the three weeks I've had the car in my possession. I was just wondering what could be causing this and how to alleviate the issue (if it isn't a one off thing). Any help or insight is much appreciated!
More details: - Opened garage door - Started car with foot on brake and within a second or two, put it in reverse - Let foot off of brake and car started backing up slowly (at first) - About a second later, the car started surging...RPM oscillated between roughly 800 and 1000 rpm...I could also feel the car surging as it was reversing - This occurred for about two or three cycles (i.e. it surged from 800 to 1000 rpm and back down two or three times) - Afterwards, I stopped the car on my driveway for a minute trying to see if the problem would arise again...it did not - Idling on the driveway was a bit rough - On my drive to work, I noticed no rough idles nor any surging Last edited by Frozen Fractals; 07-06-2015 at 08:19 AM.. |
07-06-2015, 08:15 AM | #2 |
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Drives: 2011 335i xDrive
Join Date: Sep 2014
Location: Mims, FL
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I notice these symptoms with mine as well, it gets even more exaggerated when the wheel is turned also.
Would like to see if someone has any insight on this. |
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07-06-2015, 08:22 AM | #3 |
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Interesting to see that I'm not the only one experiencing this. Is your experience identical to mine? Perhaps it's due to a cold start and too rich of a fuel/air mixture? I do sometimes notice the smell of unburned fuel if after a cold start. The smell goes away after the CATs warm up. I wonder if my fuel pump is going...or maybe a MAF sensor cleaning is due for me?
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07-06-2015, 09:26 AM | #4 |
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Drives: 2011 335i xDrive
Join Date: Sep 2014
Location: Mims, FL
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Yes, I have a hesitation at low RPM's when the wheel is turned and I let it idle, or move at a crawl. I took it to a dealer and did a test drive with a tech after they said they couldn't reproduce it. I was able to do it for him and he couldn't give me an answer for it. They just updated my DME and called it a day. They said since there were no codes and no driving abnormalities, they weren't worried about it.
I always have the fuel smell as I have the VRSF cat-less DP, but my car did this prior to installing that as well. So cats or no cats, the symptoms were the same. I also clean my MAF every oil change as I run the oiled BMS filter on their intake, and those can potentially gunk up the MAF causing false readings, so I use the CRC (I think that's the brand) MAF cleaner. Also, if the fuel pump was going you would think we would have other symptoms; error code of some sort, long startup cranks, etc.... I'm at a loss as to what is causing it, other than maybe for me, the power steering pump pulling to much power at idle, causing the engine to nearly stall, but the tech said that was unlikely at 35K. Who knows. |
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07-06-2015, 01:38 PM | #5 |
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Hmmm, I get hesitation as well when moving my wheel with the foot on my brake. Wonder if it is the PS pump that's causing this...also, I get surging when I applying the brakes and then release at times (especially when I am crawling in traffic or pulling into my garage/parking spaces). I've read about the NIC issues...wonder if that has anything to do with it too?
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07-06-2015, 03:27 PM | #6 |
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it does to my 2011 e90 328i too. Idk why.... it's on and off. it tends to do when you release your foot from your brake. never happened yet when gear is in reverse, but definitely have happened when it's in drive.
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07-06-2015, 07:56 PM | #7 |
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I've experienced this in my 99' M3, 02' M3, and now my 11' 335i. Before all of them I drove a 91' 300zx twin turbo that did a similar rev/surge at low RPM's and it was in the manual as normal for a cold start (which may be why it's hard to replicate). I don't know this for a fact but I always assumed this was programmed in as a way to slightly warm the engine in the bmw and circulate oil upon a cold start. I haven't found anything to support this theory but all my cars have been reliable and checked out without codes historically. So I have just assumed this is normal. I wouldn't worry without other symptoms.
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