M5 engine problems
Discussion
My M5 has just returned from the dealer for the second time 
. Over the last couple of months it's developed an intermittent problem.
Basically, if you're 'pressing on' (I would say 'thrashing' it, but that's not true
) at high revs it suddenly loses power and behaves as if the mixture is heroically wrong, someone's unplugged a couple of plug leads, or stuffed a banana up one of the exhaust pipes.
If you back off, you find that for the next 5 mins or so you can use part throttle, but if you try and accelerate even slightly agressively it refuses to run smoothly. It's a kind-of 'fluttering' sensation.
Anyway, the local dealer changed a camshaft sensor the first time. This did bugger all, but today they had the car for 7 hours or so and spent nearly all that time running diagnostics. Apparently all they found was 16 'logged' misfires which pointed to a cam sensor (again). They cleaned some oil filter, and also re-set the adaptive maps (they said they found a problem at one of the map points). The best part was that they did this all FOC (which was nice!
).
Anyway, we'll see how it goes, but I just wondered if anyone else had had similar problems, and whether you successfully cured the problem?
PS. Anyone going to VW this weekend from here?
. Over the last couple of months it's developed an intermittent problem. Basically, if you're 'pressing on' (I would say 'thrashing' it, but that's not true
) at high revs it suddenly loses power and behaves as if the mixture is heroically wrong, someone's unplugged a couple of plug leads, or stuffed a banana up one of the exhaust pipes. If you back off, you find that for the next 5 mins or so you can use part throttle, but if you try and accelerate even slightly agressively it refuses to run smoothly. It's a kind-of 'fluttering' sensation.
Anyway, the local dealer changed a camshaft sensor the first time. This did bugger all, but today they had the car for 7 hours or so and spent nearly all that time running diagnostics. Apparently all they found was 16 'logged' misfires which pointed to a cam sensor (again). They cleaned some oil filter, and also re-set the adaptive maps (they said they found a problem at one of the map points). The best part was that they did this all FOC (which was nice!
). Anyway, we'll see how it goes, but I just wondered if anyone else had had similar problems, and whether you successfully cured the problem?
PS. Anyone going to VW this weekend from here?
superlightr,
Thanks for the feedback - they have advised that we 'try it' for a week or so, and potentially bring it back so the chief techie can drive around in it for a while, if its still 'doing its thang'.
So far, I can report that the cold running (first 5 mins) is much improved; less sensitive to throttle and we've got rid of the annoying rev-die-rev-die-rev which always happened when reversing.
But if you've had the same problem I might take it back anyway. I'm going to have trouble, though, cos they have already swallowed (allegedly) £700 worth of diagnostics which aren't covered by the warranty. So anything else is likely to be chargeable
Thanks for the feedback - they have advised that we 'try it' for a week or so, and potentially bring it back so the chief techie can drive around in it for a while, if its still 'doing its thang'.
So far, I can report that the cold running (first 5 mins) is much improved; less sensitive to throttle and we've got rid of the annoying rev-die-rev-die-rev which always happened when reversing.
But if you've had the same problem I might take it back anyway. I'm going to have trouble, though, cos they have already swallowed (allegedly) £700 worth of diagnostics which aren't covered by the warranty. So anything else is likely to be chargeable
Oh dear. Things are going downhill. Took the car out yesterday, about 15 mins into the journey I took the opportunity to put my foot down, and at about 5500 rpm I changed up. It was a bit of a violent 'cut' of power which I thought was odd. Picked the next gear, put my foot down again and .. nothing. No power at all 
.
We ground to a halt (engine still running) and worked out that it wouldn't rev over 3k revs. Must be a 'get home' mode or something. Everything else seemed fine. Got home, turned engine off, waited 10 sec, turned it on again and it revved fine. Must quiz BMW as to whether their ECU runs Windows ..
Anyway, the upshot is that i'm going to take the car in tomorrow morning to the local dealers and have a serious chat with them about o-rings. Superlightr, could you let me know which dealer fixed your car eventually? I'd like to be able to get them to talk to each other.
. We ground to a halt (engine still running) and worked out that it wouldn't rev over 3k revs. Must be a 'get home' mode or something. Everything else seemed fine. Got home, turned engine off, waited 10 sec, turned it on again and it revved fine. Must quiz BMW as to whether their ECU runs Windows ..
Anyway, the upshot is that i'm going to take the car in tomorrow morning to the local dealers and have a serious chat with them about o-rings. Superlightr, could you let me know which dealer fixed your car eventually? I'd like to be able to get them to talk to each other.
Veeeeeery interesting, superlightr. Ta very much for the information about the dealer. I also posted on bmwm5.com and some guy has also had the same problems and has given me the name of a chap who I should ask my dealer to contact.
The thot plickens ..
(many thanks for the info, btw -
- it's this kind of information which is worth its weight in gold to me)
The thot plickens ..
(many thanks for the info, btw -
- it's this kind of information which is worth its weight in gold to me)
Hmmm. Car just cut out for the second time. My wife was driving it, went to overtake, and it just cut out. Took it straight back to the dealer and they reckon it's airflow sensors. According to them, the ECU shut down to <3000 rpm to protect the Cat's. Hmmm. Since i've just removed them from the Cerb, and realise how little they do to save the environment anyway, i'd much rather try to save my wife & son by preserving engine power than the bl**dy cats.
Anyway, apart from this recent mishap, I mailed the dealer about 2 weeks ago with lots of information about the possible problems, but got NOTHING in reply. Only after I mailed him again, then again, then phoned and left a message did he call me back. This was two days ago. His only question was: "Has it happened again?". I said no - he said "good - looks like we've fixed it, then". Famous last words? Looks like it.
Am going to call him on Monday and have a right rant at him. I can't believe that they were so certain that it was sorted, then almost the next day it happened again.
Anyway, apart from this recent mishap, I mailed the dealer about 2 weeks ago with lots of information about the possible problems, but got NOTHING in reply. Only after I mailed him again, then again, then phoned and left a message did he call me back. This was two days ago. His only question was: "Has it happened again?". I said no - he said "good - looks like we've fixed it, then". Famous last words? Looks like it.
Am going to call him on Monday and have a right rant at him. I can't believe that they were so certain that it was sorted, then almost the next day it happened again.
Superlightr - the car is getting worse which is a good/bad thing I guess! It cut out twice on Saturday whilst I was driving it - simply accelerating up a slip road onto the A34!
I pulled over, restarted the engine, and all was fine again.
Anyway, tried to rant at my dealer this morning, but the guy i'm dealing with was 'with a customer'. The other person I spoke to recommended that I get the car recovered also! So I think I might arrange that for this afternoon.
The reason for replying is to ask you, superlightr, for either your surname or reg. number. Please feel free to mail me offline - i've just spoken to the very friendly Duncan at Vines of Gatwick and he needs these details before he can do a search for your car. If you're happy to give these out, then great.
On another note, a chap on bmwm5.com has given me the name of a guy at BMW GB who has diagnosed & fixed this problem before. So I called them, and got another friendly lady who took all my particulars!
So.. things are moving forward. Still got a car which doesn't work and is dangerous to drive, though.
I pulled over, restarted the engine, and all was fine again.
Anyway, tried to rant at my dealer this morning, but the guy i'm dealing with was 'with a customer'. The other person I spoke to recommended that I get the car recovered also! So I think I might arrange that for this afternoon.
The reason for replying is to ask you, superlightr, for either your surname or reg. number. Please feel free to mail me offline - i've just spoken to the very friendly Duncan at Vines of Gatwick and he needs these details before he can do a search for your car. If you're happy to give these out, then great.
On another note, a chap on bmwm5.com has given me the name of a guy at BMW GB who has diagnosed & fixed this problem before. So I called them, and got another friendly lady who took all my particulars!
So.. things are moving forward. Still got a car which doesn't work and is dangerous to drive, though.
Superlightr, many thanks for the details. I called Duncan back and we talked about the (many!) parts replaced on your car. However, although the list showed work on the o-rings on your car, the last entry (date order) was a change to both air-mass-flow meters on the engine. This is currently what my local dealer are replacing, so I wonder whether this might be the actual cause of the problem? It certainly seems plausible - do you remember when these were changed - was this related to the problem, or not?
I'm going to wait until i've spoken directly with BMW GB about this one - i've left a message and will chase them today, but it would be interesting to see if their thoughts tally with those of Vines/Gatwick and my local dealer.
Once again, many thanks for your details - I actually feel like i'm helping to sort this problem, rather than leaving it in the hands of my dealer.
PS. What's your favourite tipple - i've got to repay you somehow!
I'm going to wait until i've spoken directly with BMW GB about this one - i've left a message and will chase them today, but it would be interesting to see if their thoughts tally with those of Vines/Gatwick and my local dealer.
Once again, many thanks for your details - I actually feel like i'm helping to sort this problem, rather than leaving it in the hands of my dealer.
PS. What's your favourite tipple - i've got to repay you somehow!
Hope i'm not boring anyone, but a quick update! 
:
Car is still with dealer, we have a 'BMW Assist' Ovlov until Monday. They have replaced the airflow 'mass' -ometers (technical term) and have not managed to reproduce the fault today. I mailed them the other day describing the fault in detail, and how to reproduce it along with the 'flat spot' at 5000rpm and the bad cold running, so I assume they know what they should be doing!
However, on the test drives they noticed a 'knocking' which I reported to them the first time it came in for this 'cutting out' fault (they said they couldn't find anything and they'd 'tightened everything up' just in case) and have decided it's something to do with the steering rack and think it's serious enough to keep in.
So .. car still in garage, major fault potentially fixed (but we still have a new ECU or software on order) and new fault with steering rack awaiting a fix.
Ho hum.
: Car is still with dealer, we have a 'BMW Assist' Ovlov until Monday. They have replaced the airflow 'mass' -ometers (technical term) and have not managed to reproduce the fault today. I mailed them the other day describing the fault in detail, and how to reproduce it along with the 'flat spot' at 5000rpm and the bad cold running, so I assume they know what they should be doing!
However, on the test drives they noticed a 'knocking' which I reported to them the first time it came in for this 'cutting out' fault (they said they couldn't find anything and they'd 'tightened everything up' just in case) and have decided it's something to do with the steering rack and think it's serious enough to keep in.
So .. car still in garage, major fault potentially fixed (but we still have a new ECU or software on order) and new fault with steering rack awaiting a fix.
Ho hum.
Nobody has mentioned the crank sensor 
. One thing I should point out, however, is that when the car 'cuts out' it actually just swaps to a 'get home' mode which means you can't exceed 3,000 rpm. If you try to rev the engine, it gently cuts the revs as you approach 3k, ultimately resulting in a vrrm - vrrm - vrrm even with your foot flat on the floor. Most odd!
. One thing I should point out, however, is that when the car 'cuts out' it actually just swaps to a 'get home' mode which means you can't exceed 3,000 rpm. If you try to rev the engine, it gently cuts the revs as you approach 3k, ultimately resulting in a vrrm - vrrm - vrrm even with your foot flat on the floor. Most odd!
domster said: Therefore, what does the rev counter do when the fault occurs? If the rev counter is OK then I would guess that the crank sensor is not to blame.
The rev. counter behaves completely normally - shows the revs accurately I believe.
The current theory is air mass meters. They have had the car for a few days now and are trying to reproduce the fault with the new meters, without success I think. I wonder how the meters measure the 'air mass' - there are a number of different types, aren't there - hot wire, flap, etc.
Dealer has already downloaded from the (apparently more than one) computers on the car - the very first time it went in they found that a camshaft sensor needed to be replaced, and they reset the adaptive maps so it would re-learn the fuelling, etc. The second time they simply found logs about 'insufficient fuel' I think, and so checked the fuel pump and filter (and replaced the filter).
The last time it happened time we managed to get the car to the dealer immediately after it went into 'limp home' mode and they seemed to immediately glean from the logs that it was air mass meters. How they missed this before I have no idea.
One interesting thing was that apparently the ECU starts overwriting previous events if there are too many. And I imagine that (as with programming) the original event is the one you're more interested in.
As well as changing the meters they want to fit a new ECU from Germany - normally these come 'empty' and the dealer downloads onto them, but in my case 'Germany' are going to supply a 'ready to fit' ECU. Whether this is software or map data, i've no idea. But with any luck this will sort out the flat spot at about 5k rpm which they reckon their M5 demo also has.
Can't wait to get it back!
The last time it happened time we managed to get the car to the dealer immediately after it went into 'limp home' mode and they seemed to immediately glean from the logs that it was air mass meters. How they missed this before I have no idea.
One interesting thing was that apparently the ECU starts overwriting previous events if there are too many. And I imagine that (as with programming) the original event is the one you're more interested in.
As well as changing the meters they want to fit a new ECU from Germany - normally these come 'empty' and the dealer downloads onto them, but in my case 'Germany' are going to supply a 'ready to fit' ECU. Whether this is software or map data, i've no idea. But with any luck this will sort out the flat spot at about 5k rpm which they reckon their M5 demo also has.
Can't wait to get it back!
Cheers, superlightr - I think the cats are ok as we've just had (within the last 4 weeks) a MoT, and this was done at another garage, so hopefully no cheating! 
Yes, I do intend to keep the car; we've only had it about 9 months and so the depreciation will be steep if we got rid of it now .. plus I have a feeling that if they can fix it it's still the best sub-30K sports saloon that money can buy. We'll be extending the warranty, tho' ..
Yes, I do intend to keep the car; we've only had it about 9 months and so the depreciation will be steep if we got rid of it now .. plus I have a feeling that if they can fix it it's still the best sub-30K sports saloon that money can buy. We'll be extending the warranty, tho' ..
Update: Car is now performing virtually faultlessly - easy to drive when cold, smooth throughout the rev range and more importantly - MORE POWER!!
I'd say that there's an extra 40 or so horses under the bonnet - i'm a great believer in the inability of an average driver (ie. me) to detect small increases in BHP with a powerful car, but I can safely say that I really noticed the difference when the car came back! Infact, the family all went out on Sunday and I quite happily kept up with a new M3 convertible down a dual carriageway all the way up to highly illegal speeds! So it looks like i've got a little nearer to 400BHP now, which is nice!
The only problem, really, is getting my dealer to document what they've done - i've been asking for this ever since this problem started, and i'm starting to wonder if there isn't a conspiracy going on. The first time they ran their diagnostics I asked for documentation. Nothing. Then, it came in for a second time, and I pointed out that I had no documentation. Then, a third time they stung me for £120 for a fuel filter which wasn't the cause of the problem and i've still not got either (a) an invoice for the filter or (b) ANY documentation about the whole episode!
I mailed my contact at the dealer today and he says it's 'in the post'
.
I'd say that there's an extra 40 or so horses under the bonnet - i'm a great believer in the inability of an average driver (ie. me) to detect small increases in BHP with a powerful car, but I can safely say that I really noticed the difference when the car came back! Infact, the family all went out on Sunday and I quite happily kept up with a new M3 convertible down a dual carriageway all the way up to highly illegal speeds! So it looks like i've got a little nearer to 400BHP now, which is nice!
The only problem, really, is getting my dealer to document what they've done - i've been asking for this ever since this problem started, and i'm starting to wonder if there isn't a conspiracy going on. The first time they ran their diagnostics I asked for documentation. Nothing. Then, it came in for a second time, and I pointed out that I had no documentation. Then, a third time they stung me for £120 for a fuel filter which wasn't the cause of the problem and i've still not got either (a) an invoice for the filter or (b) ANY documentation about the whole episode!
I mailed my contact at the dealer today and he says it's 'in the post'
.
superlightr said:
did they change the ecu software??
I don't know! It's difficult for me to phone or get down to the dealer at the moment and that's why I want them to document what they've done!
I would still get them to check/inspect the cats as mine were damaged.
They are generally reluctant to do anything, so it's going to be a struggle. But I take your point - can they tell by inspection whether they are damaged or not? Aren't there Co2 sensors downstream of the cat's? Perhaps they could give me the readings of a 'perfect' car and compare them to mine?
ps. did they offer any compensation to ease your woes? if not ask/demand and you will be given.
Don't be silly!! It was all I could do to get them to fix the b*gger! I might start talking about it, though, before the iron gets too cold!
Once again, thanks for your help, sir. Mail me your address and i'll get Tescos to deliver some bitter/lager/wine to thank you for your trouble!
Not bad, thanks - it's still not perfect; lots of 'hunting' of revs when manoeuvering at slow speed, and it's still difficult to smoothly engage gears at slow speed. But AT LEAST IT ISN'T CUTTING OUT ANYMORE !!!
Only one light left now before it needs a service, and i'm going to change dealer .. it's a shame that some dealers are rubbish, but I guess you've got to have a few bad eggs.
Only one light left now before it needs a service, and i'm going to change dealer .. it's a shame that some dealers are rubbish, but I guess you've got to have a few bad eggs.
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