M5. Lumpy idle when stone cold anyone?
Discussion
Over the past couple of weeks ive noticed this and it seems im not alone. Only problem is i cannot find a definitive answer to why!!
Symptoms: If left for a couple of days, when started the car has a lumpy idle and doesnt go into 'cold start' mode for a good 10 to 20 seconds. Instead of the smooth, but throaty 1200rpm cold start it bounces up and down between 800 and 900 rpm and sometimes even lower. Its like its not getting enough fuel or air. On one occasion i pressed the gas pedal to see if i could force it higher but the revs dropped even lower, almost stalling for a second or two until i released. Then it went back to doing its bouncy, odd idle. I pressed the pedal a bit harder and after a slight cough the car reverted back to a smooth 1200rpm. After that it was normal and when stationary it sat nicely at 900rpm as per standard.
Note: If left to idle and warm normally on the drive, it will smooth out and raise to 1200rpm as per regular cold start (see video) before slowing once warmed.
Now, when cold, but not left for more than 24 hours the car starts fine. ie, if ive driven it in the morning it'll start fine at night. Its only when left longer than 24 hrs it has this lumpy idle issue.
Anyone else had this or know of it. Ive seen loads of it on the net but ne word on reasons or rhymes.
Plugs are only 20k old (due every 30k or so i believe), service was recent and all filters are virually new. Only thing ive heard that may be responsible is MAF or Injectors. My MAFs were checked recently im sure. Oh, and i only run it on VPower.
The car drives perfectly asside from this minor niggle.
Video:
http://s251.photobucket.com/albums/gg306/niacuk/?a...
Symptoms: If left for a couple of days, when started the car has a lumpy idle and doesnt go into 'cold start' mode for a good 10 to 20 seconds. Instead of the smooth, but throaty 1200rpm cold start it bounces up and down between 800 and 900 rpm and sometimes even lower. Its like its not getting enough fuel or air. On one occasion i pressed the gas pedal to see if i could force it higher but the revs dropped even lower, almost stalling for a second or two until i released. Then it went back to doing its bouncy, odd idle. I pressed the pedal a bit harder and after a slight cough the car reverted back to a smooth 1200rpm. After that it was normal and when stationary it sat nicely at 900rpm as per standard.
Note: If left to idle and warm normally on the drive, it will smooth out and raise to 1200rpm as per regular cold start (see video) before slowing once warmed.
Now, when cold, but not left for more than 24 hours the car starts fine. ie, if ive driven it in the morning it'll start fine at night. Its only when left longer than 24 hrs it has this lumpy idle issue.
Anyone else had this or know of it. Ive seen loads of it on the net but ne word on reasons or rhymes.
Plugs are only 20k old (due every 30k or so i believe), service was recent and all filters are virually new. Only thing ive heard that may be responsible is MAF or Injectors. My MAFs were checked recently im sure. Oh, and i only run it on VPower.
The car drives perfectly asside from this minor niggle.
Video:
http://s251.photobucket.com/albums/gg306/niacuk/?a...
Not experienced it Eddie and I leave ours for up to a week during trips. It does as you say look like a cold start but would not expect that during the current temps.
I like you explaining to the lady that it's low on fuel lol, same amount as is in ours after we have done 750 miles in the last week and it has skinted me!!!!
Anyway, I will ask a mate who is a specialist and let you know.
Off topic I went to start ours yesterday after using it all week and both key fobs would not open the car. I had to use the caveman key and manually open the door which set the alarm off every time.
A quick search on tinternet showed it could be the diversity antennae at the rear of the car which is some sort of amplifier for the remote locking antennae. I waited half the day for the thing to dry out and it works but man was it annoying. I don't know whether to replace it or just live with it.
Anyone else had this?
I like you explaining to the lady that it's low on fuel lol, same amount as is in ours after we have done 750 miles in the last week and it has skinted me!!!!
Anyway, I will ask a mate who is a specialist and let you know.
Off topic I went to start ours yesterday after using it all week and both key fobs would not open the car. I had to use the caveman key and manually open the door which set the alarm off every time.
A quick search on tinternet showed it could be the diversity antennae at the rear of the car which is some sort of amplifier for the remote locking antennae. I waited half the day for the thing to dry out and it works but man was it annoying. I don't know whether to replace it or just live with it.
Anyone else had this?
M5MarkM said:
I'm a dinsoaur.... I don;t beleive a set of plugs can do 30k.... I change every 15k at most. Might be a waste of money but gives me a warm feeling changing them 
Id agree with the plugs idea 99% of the time but every thread ive read about this has already had that suggestion and had it ruled out once new plugs had been fitted. Only one ive seen thats involved the plugs was a guy who had a loose plug and the rough idle was caused by poor firing. Ive read about injector failure, MAFs dirty, air leak in the inlet, bad fuel (hard to believe it could be this when using VPower) and temp sensor issues (most likely). There was even suggestion that it could be a software issue due to recent updates which i can believe. Not once have i read about an actual cause though, just suggestion.
Oh, 'that lady' is my wife. lol
and I thought she would at least know that it was a low fuel warning as these cars do like a drink! Eddie, I would be interested to know the cause. Mine has exactly the same symptoms over the past of couple of weeks, apart from the rough idle only lasts for about 10 seconds before it settles at 1200rpm. Had recent oil and filter change (rough idle was there prior) and plenty of life left in plugs. like yours, mine is fine during day, even if left for hours. will only occur in mornings and on some occasions (like today) settled straight to 1200rpm after a 2-3 seconds rather than the 10. i have fully comprehensive warranty but problem not bad enough for me to hand over to the dealers.
ecain63 said:
Over the past couple of weeks ive noticed this and it seems im not alone. Only problem is i cannot find a definitive answer to why!!
Symptoms: If left for a couple of days, when started the car has a lumpy idle and doesnt go into 'cold start' mode for a good 10 to 20 seconds. Instead of the smooth, but throaty 1200rpm cold start it bounces up and down between 800 and 900 rpm and sometimes even lower. Its like its not getting enough fuel or air. On one occasion i pressed the gas pedal to see if i could force it higher but the revs dropped even lower, almost stalling for a second or two until i released. Then it went back to doing its bouncy, odd idle. I pressed the pedal a bit harder and after a slight cough the car reverted back to a smooth 1200rpm. After that it was normal and when stationary it sat nicely at 900rpm as per standard.
Note: If left to idle and warm normally on the drive, it will smooth out and raise to 1200rpm as per regular cold start (see video) before slowing once warmed.
Now, when cold, but not left for more than 24 hours the car starts fine. ie, if ive driven it in the morning it'll start fine at night. Its only when left longer than 24 hrs it has this lumpy idle issue.
Anyone else had this or know of it. Ive seen loads of it on the net but ne word on reasons or rhymes.
Plugs are only 20k old (due every 30k or so i believe), service was recent and all filters are virually new. Only thing ive heard that may be responsible is MAF or Injectors. My MAFs were checked recently im sure. Oh, and i only run it on VPower.
The car drives perfectly asside from this minor niggle.
Video:
http://s251.photobucket.com/albums/gg306/niacuk/?a...
Symptoms: If left for a couple of days, when started the car has a lumpy idle and doesnt go into 'cold start' mode for a good 10 to 20 seconds. Instead of the smooth, but throaty 1200rpm cold start it bounces up and down between 800 and 900 rpm and sometimes even lower. Its like its not getting enough fuel or air. On one occasion i pressed the gas pedal to see if i could force it higher but the revs dropped even lower, almost stalling for a second or two until i released. Then it went back to doing its bouncy, odd idle. I pressed the pedal a bit harder and after a slight cough the car reverted back to a smooth 1200rpm. After that it was normal and when stationary it sat nicely at 900rpm as per standard.
Note: If left to idle and warm normally on the drive, it will smooth out and raise to 1200rpm as per regular cold start (see video) before slowing once warmed.
Now, when cold, but not left for more than 24 hours the car starts fine. ie, if ive driven it in the morning it'll start fine at night. Its only when left longer than 24 hrs it has this lumpy idle issue.
Anyone else had this or know of it. Ive seen loads of it on the net but ne word on reasons or rhymes.
Plugs are only 20k old (due every 30k or so i believe), service was recent and all filters are virually new. Only thing ive heard that may be responsible is MAF or Injectors. My MAFs were checked recently im sure. Oh, and i only run it on VPower.
The car drives perfectly asside from this minor niggle.
Video:
http://s251.photobucket.com/albums/gg306/niacuk/?a...
No doubt we will have to return the car every other day over 3 weeks to resolve.
ecain63 said:
^^ If mine continues this idle issue i'll take mine in to my dealer for a fix. Warranty should cover this no worries. Probably something simple like a vacuum leak or sensor, but knowing these cars it'll cost £5 for the sensor or hose and £1Billion in labour to sort.
Edited by abbaszb on Wednesday 29th August 10:26
Little update:
The car is still idling oddly after being left for more than 24hrs so im assuming something is up. Now, on top of this its started running oddly when hot. At idle when hot it runs quite loudly and feels quite gritty.
I'm thinking thermostat, vacuum issue or something similar. Either way im going to give my dealer a call tomorrow. There is a chance they could have done some update when it was in for the new rack and that's upsetting it but its not feeling quite right currently. I'd even go so far as to say it doesn't feel or sound right when driving round town but that might just be paranoia.
More to follow!
The car is still idling oddly after being left for more than 24hrs so im assuming something is up. Now, on top of this its started running oddly when hot. At idle when hot it runs quite loudly and feels quite gritty.
I'm thinking thermostat, vacuum issue or something similar. Either way im going to give my dealer a call tomorrow. There is a chance they could have done some update when it was in for the new rack and that's upsetting it but its not feeling quite right currently. I'd even go so far as to say it doesn't feel or sound right when driving round town but that might just be paranoia.
More to follow!
mine has no issue when cold and i leave it at airports for a week all the time (its at heathrow as I type).
however your last post mentions that your warm idle gets loud.... well mine has always done this, on warm idle it will range from 700-900rpm, with a very noticable change in engine tone.
when the car was stock this was almost unoticable but now I have no silencers it becomes pretty loud and is a very noticible change when it does it sitting in traffic.
it doesnt effect anything and is smooth etc etc... just clearly something is changing in the mapping (due to sensor etc), and it does seem happier when its idling at 700rpm (and almost completly quiet in the car).... as you know I run mine only on normal unleaded so I dont think your issue is fuel related...
To me it seems the engine has lost its map for cold start, we all know its an adaptive ecu.... maybe it needs an adaptive map reset when its cold?
however your last post mentions that your warm idle gets loud.... well mine has always done this, on warm idle it will range from 700-900rpm, with a very noticable change in engine tone.
when the car was stock this was almost unoticable but now I have no silencers it becomes pretty loud and is a very noticible change when it does it sitting in traffic.
it doesnt effect anything and is smooth etc etc... just clearly something is changing in the mapping (due to sensor etc), and it does seem happier when its idling at 700rpm (and almost completly quiet in the car).... as you know I run mine only on normal unleaded so I dont think your issue is fuel related...
To me it seems the engine has lost its map for cold start, we all know its an adaptive ecu.... maybe it needs an adaptive map reset when its cold?
andygtt said:
mine has no issue when cold and i leave it at airports for a week all the time (its at heathrow as I type).
however your last post mentions that your warm idle gets loud.... well mine has always done this, on warm idle it will range from 700-900rpm, with a very noticable change in engine tone.
when the car was stock this was almost unoticable but now I have no silencers it becomes pretty loud and is a very noticible change when it does it sitting in traffic.
it doesnt effect anything and is smooth etc etc... just clearly something is changing in the mapping (due to sensor etc), and it does seem happier when its idling at 700rpm (and almost completly quiet in the car).... as you know I run mine only on normal unleaded so I dont think your issue is fuel related...
To me it seems the engine has lost its map for cold start, we all know its an adaptive ecu.... maybe it needs an adaptive map reset when its cold?
The revs rising and dropping a bit, when it is warm is normal. BMW had to get the engine to pass EURO IV, which is a mean feat in itself. By raising and dropping the revs, the engine is effectively playing with the heat generated in the cats, and thus with their efficiency. That's what a tech as Sytner Harold Wood told me. It could also be a symptom for a lambda sensor about to go out. Then though, you should expect a yellow engine light on the dash pretty soon.... however your last post mentions that your warm idle gets loud.... well mine has always done this, on warm idle it will range from 700-900rpm, with a very noticable change in engine tone.
when the car was stock this was almost unoticable but now I have no silencers it becomes pretty loud and is a very noticible change when it does it sitting in traffic.
it doesnt effect anything and is smooth etc etc... just clearly something is changing in the mapping (due to sensor etc), and it does seem happier when its idling at 700rpm (and almost completly quiet in the car).... as you know I run mine only on normal unleaded so I dont think your issue is fuel related...
To me it seems the engine has lost its map for cold start, we all know its an adaptive ecu.... maybe it needs an adaptive map reset when its cold?
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