Car revving up and down on it's own when driving?!

FRG · 07-15-2013, 07:55 AM

Has anyone else had this problem? This happened once over the weekend and also just now. When I'm driving at 30mph with virtually no throttle on the revs go up by about 200rpm them drop off by about 200rpm below normal, then back up, then drop off etc etc.. it's also causing the car to pick up and drop speed as it does so (as you'd expect). There's no issue at all if I bury the throttle it's picks straight up and won't go back to doing it again

. Running on Shell as always btw.

Thanks for reading and I hope someone can point me in the direction of the problem.

Cheers

Dave

basim07 · 07-15-2013, 05:36 PM

Have you got access do a diagnostics computer at all? Thatd be the best way to go about this first
It could be a load of different things

Ive experiened similar things in the past but affected me more at idle and for me it was the MAF sensor, similarly could be intake related

J Dub · 07-15-2013, 05:39 PM

I had something very like this on my E46 petrol model, I had nightmare thoughts in my head, i had not screwed the oil filler cap on correctly, so took it off, put it on right and it was fixed. May have nothing to do with it, yet that is what it was for me, easiest fix to what I thought was going to be a horror story of all time.

07-15-2013, 07:55 AM	#1
FRG Captain 67 Rep 646 Posts Drives: E91 325d M Sport Join Date: May 2012 Location: east midlands iTrader: (1)	Car revving up and down on it's own when driving?! Has anyone else had this problem? This happened once over the weekend and also just now. When I'm driving at 30mph with virtually no throttle on the revs go up by about 200rpm them drop off by about 200rpm below normal, then back up, then drop off etc etc.. it's also causing the car to pick up and drop speed as it does so (as you'd expect). There's no issue at all if I bury the throttle it's picks straight up and won't go back to doing it again . Running on Shell as always btw. Thanks for reading and I hope someone can point me in the direction of the problem. Cheers Dave
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07-15-2013, 05:36 PM	#2
basim07 First Lieutenant 28 Rep 358 Posts Drives: E93 330i & E90 330D Join Date: Mar 2013 Location: Manchester iTrader: (0)	Have you got access do a diagnostics computer at all? Thatd be the best way to go about this first It could be a load of different things Ive experiened similar things in the past but affected me more at idle and for me it was the MAF sensor, similarly could be intake related
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07-15-2013, 05:39 PM	#3
J Dub Private First Class 8 Rep 199 Posts Drives: E90 2007 MSport 2.0d Join Date: Jun 2013 Location: South West England iTrader: (0)	I had something very like this on my E46 petrol model, I had nightmare thoughts in my head, i had not screwed the oil filler cap on correctly, so took it off, put it on right and it was fixed. May have nothing to do with it, yet that is what it was for me, easiest fix to what I thought was going to be a horror story of all time. __________________ Cheers J
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