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Fluctuating revs when idle
- Daaaaan
- Member
- Posts: 128
- Joined: Wed Jun 23, 2010 2:17 pm
Fluctuating revs when idle
Hey guys
I turn to this community again regarding an issue because it's been very helpful and prompt each time...I've had this problem since i got the car 2 years ago, but never really bothered with it...until the issue started to occur more frequently:
Sometimes, maybe once a day, after i drive the car normally around town and stop at a red light with the car in neutral, the revs drop from 850 rot/min to 400-500 rot/min for a second, the car trembles as you would expect, them they go back up and everything is ok. I've noticed this happening more frequently if i stop on a slope...i think. Although it happens on perfectly level roads also.
On rare occasions, maybe once every 2 weeks, the engine comes to a complete stop, as if you were releasing the clutch without putting the car in neutral.
Anyone else had this annoying problem?
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I turn to this community again regarding an issue because it's been very helpful and prompt each time...I've had this problem since i got the car 2 years ago, but never really bothered with it...until the issue started to occur more frequently:
Sometimes, maybe once a day, after i drive the car normally around town and stop at a red light with the car in neutral, the revs drop from 850 rot/min to 400-500 rot/min for a second, the car trembles as you would expect, them they go back up and everything is ok. I've noticed this happening more frequently if i stop on a slope...i think. Although it happens on perfectly level roads also.
On rare occasions, maybe once every 2 weeks, the engine comes to a complete stop, as if you were releasing the clutch without putting the car in neutral.
Anyone else had this annoying problem?
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- Daaaaan
- Member
- Posts: 128
- Joined: Wed Jun 23, 2010 2:17 pm
Re: Fluctuating revs when idle
Pls delete one of the threads, i double posted and cannot delete from phone
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Sent from my HTC One_M8 using Tapatalk
- Ricey01
- Member
- Posts: 363
- Joined: Sat Dec 03, 2011 8:38 pm
Re: Fluctuating revs when idle
Left bollock wagered on the MAF sensor.
- Daaaaan
- Member
- Posts: 128
- Joined: Wed Jun 23, 2010 2:17 pm
Re: Fluctuating revs when idle
Could you please explain? I don't understand...Ricey01 wrote:Left bollock wagered on the MAF sensor.
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-
- Member
- Posts: 211
- Joined: Mon Jun 10, 2013 10:48 pm
Re: Fluctuating revs when idle
Mass Air Flow sensor........I would have thought that the Engine Management light would have come on if this was at fault though?
2003 Z4 3.0i Auto Maldives Blue with Ivory Leather, Stubby, Angel eyes, chrome grills, zunsport lower mesh grill, M style pedals, drilled disc
- Swiftly
- Lifer
- Posts: 8817
- Joined: Wed Dec 28, 2011 10:43 pm
- Location: Edinburgh
Re: Fluctuating revs when idle
Have you checked if there are any error codes stored?
- Daaaaan
- Member
- Posts: 128
- Joined: Wed Jun 23, 2010 2:17 pm
Re: Fluctuating revs when idle
No lights on i'm afraid...Captainken wrote:Mass Air Flow sensor........I would have thought that the Engine Management light would have come on if this was at fault though?
I'll try and get a reading done today. Last time BMW checked for errors there was one that said that the Vanos sometimes looses connection (with the ECU i suppose)...don't know if this is related...Swiftly wrote:Have you checked if there are any error codes stored?
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- bradmarsh1989
- Senior Member
- Posts: 1281
- Joined: Sun Feb 24, 2013 6:07 pm
- Location: Bournemouth
Re: Fluctuating revs when idle
This happened to me after not starting my car for over 9 months... it would sit idle blipping up and down between 450-800rpm on in waves... engine light came on and after revving to red line a little bit to clear out the crap in the engine it settled down and no longer does this.
- Daaaaan
- Member
- Posts: 128
- Joined: Wed Jun 23, 2010 2:17 pm
Re: Fluctuating revs when idle
This is not the case for me, unfortunately...i use the car daily and reving it up does not solve the problem. I tried this and also tried using petrol from different stations. I also use only 99 or 100 octanic figures...bradmarsh1989 wrote:This happened to me after not starting my car for over 9 months... it would sit idle blipping up and down between 450-800rpm on in waves... engine light came on and after revving to red line a little bit to clear out the crap in the engine it settled down and no longer does this.
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- horseofwar
- Member
- Posts: 194
- Joined: Tue May 10, 2011 9:39 pm
- Location: Edinburgh
Re: Fluctuating revs when idle
Had this issue on my 2.0 a few months back http://www.z4-forum.com/forum/viewtopic.php?f=3&t=64194
Not sure which repair corrected the idle issue but here's the list of work that was carried out;
Timing chain replaced (chain tensioner had failed and chain had slackened, you could hear the chain rattling under the bonnet)
Coil packs (3 out of 4 were out with manufacturer limits. Likely to be your issue I think, someone with more knowledge will confirm)
Cracked manifold (not bad enough to put up error but you could hear that it was blown)
All three repaired and car now no longer does what you are describing.
Not sure which repair corrected the idle issue but here's the list of work that was carried out;
Timing chain replaced (chain tensioner had failed and chain had slackened, you could hear the chain rattling under the bonnet)
Coil packs (3 out of 4 were out with manufacturer limits. Likely to be your issue I think, someone with more knowledge will confirm)
Cracked manifold (not bad enough to put up error but you could hear that it was blown)
All three repaired and car now no longer does what you are describing.
Current: Nissan 350Z GT Pack, Alezan leather
2014- BMW Z4 2.0 SE
2013- Audi TT 3.2 V6 DSG
2012- Astra GTC 1.4T
2011- BMW Z4 3.0i full Aero kit
2014- BMW Z4 2.0 SE
2013- Audi TT 3.2 V6 DSG
2012- Astra GTC 1.4T
2011- BMW Z4 3.0i full Aero kit