M5 engine problems
Discussion
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!Often a crank sensor failure will cause the rev counter to go mental, as they normally take their feed from this.
A mechanical VANOS fault would not influence the rev counter, IMHO, nor would a typical misfire in relation to fuelling, mixture or the HT circuit (plugs, coil etc.)
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.
I had a similar problem on a previous car (Lotus Carlton). The wire was coming into the electromagnetic fields around the coils and buggering things up.
A mechanical VANOS fault would not influence the rev counter, IMHO, nor would a typical misfire in relation to fuelling, mixture or the HT circuit (plugs, coil etc.)
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.
I had a similar problem on a previous car (Lotus Carlton). The wire was coming into the electromagnetic fields around the coils and buggering things up.
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.
superlightr. I may be misreading, did they profess to have remapped the existing ECU to the latest maps ?
Our Vanos went, but the symptoms were surging of power, rather than power loss
The dealership (in a rare outbreak of competency) rebuilt the system after checking all the ECU sensors-which they do in about 10 mins. with a plug in box.
Our Vanos went, but the symptoms were surging of power, rather than power loss
The dealership (in a rare outbreak of competency) rebuilt the system after checking all the ECU sensors-which they do in about 10 mins. with a plug in box.
futie said:
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.
I imagine it would have a hot film system. Flap is stone age technology, and hot wire is dated now. Very modern engine, so would think hot film is used for MAF purposes.
Sounds like crank sensor info may be accurate and OK if rev counter behaves normally. The dealer should be able to download the engine info and see what all the signals were doing. The only time this is difficult for them to fix is when there is something physical (vanos, valve timing, head gasket), something on the HT circuit (coils, plugs etc) or something slightly out of calibration that they haven't noticed (ie MAF readings slightly out which is buggering the mixture).
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!
Hi again,
They said that they installed the new M5's software into the ecu or repalced the ecu with the new m5's one right at the end.
Get them to inspect the cats and write back that they are in good order as I suspect they are knackered by now as well.
Hey at least you got a volvo, i ended up with a vectra.
sounds like you are getting somewhere, where, I dunno but you are getting somewhere !
If you intend to keep the car you should be able to pay to extend the warrenty.
Geep us updated.
They said that they installed the new M5's software into the ecu or repalced the ecu with the new m5's one right at the end.
Get them to inspect the cats and write back that they are in good order as I suspect they are knackered by now as well.
Hey at least you got a volvo, i ended up with a vectra.
sounds like you are getting somewhere, where, I dunno but you are getting somewhere !
If you intend to keep the car you should be able to pay to extend the warrenty. Geep us updated.
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'
.
Good news !! Hopefully you have it sorted.
did they change the ecu software??
I would still get them to check/inspect the cats as mine were damaged.
put an update in a month if its still hunky dory !!
ps. did they offer any compensation to ease your woes? if not ask/demand and you will be given.
did they change the ecu software??
I would still get them to check/inspect the cats as mine were damaged.
put an update in a month if its still hunky dory !!
ps. did they offer any compensation to ease your woes? if not ask/demand and you will be given.
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!
They thought it could be the back pressure stopping the engine, when they looked at the cats they (both)had broken up, they then changed them but still with not sucess. Apparently a faulty batch. !
But if they had not checked them they would not have found they had broken up. not sure the cost but if it wasnt under warrenty is would have been about £1400 ish.
If they hadnt checked and then when the warrenty ran out or after 3 years they would have said normal wear and tear and I would have ended up with the bill. So if you can and feel brave ask them to have a look.
compensation, go for it. I got £1000 cash. after a bit of haggling although Im a bit of a mean buggeer when Im p'ssed off.
plus the other major safety faults upset me.
If a petrol head can help another petrol head to enjoy their car, then im a happy chap. Perhaps put a piston head sticker in your car to spread the word!! 
Keep us updated on how you get on and hopefuly we will kick tyres at a meet sometime.
But if they had not checked them they would not have found they had broken up. not sure the cost but if it wasnt under warrenty is would have been about £1400 ish.
If they hadnt checked and then when the warrenty ran out or after 3 years they would have said normal wear and tear and I would have ended up with the bill. So if you can and feel brave ask them to have a look.
compensation, go for it. I got £1000 cash. after a bit of haggling although Im a bit of a mean buggeer when Im p'ssed off.
plus the other major safety faults upset me. If a petrol head can help another petrol head to enjoy their car, then im a happy chap. Perhaps put a piston head sticker in your car to spread the word!!
Keep us updated on how you get on and hopefuly we will kick tyres at a meet sometime.
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.
Oh God, apologies to the afflicted for ressurecting dire memories but yes, you've guessed it, now it's my turn to get the Munchen willies.
In recent weeks, the very act of 'pressing on,' even under very deliberate, gradual anvil flattening, about 5-6000 revolutions dialled in and without warning - 'thud!'
Like some ruddy great limiter has suddenly called time on your romp, some kind of obvious 'limp home' mode (the car manages about 75 mph) but will not accelerate or allow cruise to be engaged.
Pull over, switch off and straight back on - sorted.
However, the regularity of this phenomenon, now of several weeks's standing, makes it very much part of the current repertoire.
It's in for a diagnostic check this Wednesday and to be honest, I cannot deny the creep of purest, Bavarian dread.
The car has a fBMWsh and only recently rendered me dangerously comparable to punters of Lamborghini Manchester insofar as the presentation of an Inspection II bill of such hurculean heft that I've only recently posted it to Frank Carson to inspire new material.
It consumes no oil and within the last 6 moths has had one new cat.
James, you warned me and it looks like it may now be time for me to pucker up and reach for the soap.
I just hope it's only one of the feckers!
What a pile of monkey metal!
In recent weeks, the very act of 'pressing on,' even under very deliberate, gradual anvil flattening, about 5-6000 revolutions dialled in and without warning - 'thud!'
Like some ruddy great limiter has suddenly called time on your romp, some kind of obvious 'limp home' mode (the car manages about 75 mph) but will not accelerate or allow cruise to be engaged.
Pull over, switch off and straight back on - sorted.
However, the regularity of this phenomenon, now of several weeks's standing, makes it very much part of the current repertoire.
It's in for a diagnostic check this Wednesday and to be honest, I cannot deny the creep of purest, Bavarian dread.
The car has a fBMWsh and only recently rendered me dangerously comparable to punters of Lamborghini Manchester insofar as the presentation of an Inspection II bill of such hurculean heft that I've only recently posted it to Frank Carson to inspire new material.
It consumes no oil and within the last 6 moths has had one new cat.
James, you warned me and it looks like it may now be time for me to pucker up and reach for the soap.
I just hope it's only one of the feckers! What a pile of monkey metal!
derestrictor said:
Oh God, apologies to the afflicted for ressurecting dire memories but yes, you've guessed it, now it's my turn to get the Munchen willies.
In recent weeks, the very act of 'pressing on,' even under very deliberate, gradual anvil flattening, about 5-6000 revolutions dialled in and without warning - 'thud!'
Like some ruddy great limiter has suddenly called time on your romp, some kind of obvious 'limp home' mode (the car manages about 75 mph) but will not accelerate or allow cruise to be engaged.
Pull over, switch off and straight back on - sorted.
However, the regularity of this phenomenon, now of several weeks's standing, makes it very much part of the current repertoire.
It's in for a diagnostic check this Wednesday and to be honest, I cannot deny the creep of purest, Bavarian dread.
The car has a fBMWsh and only recently rendered me dangerously comparable to punters of Lamborghini Manchester insofar as the presentation of an Inspection II bill of such hurculean heft that I've only recently posted it to Frank Carson to inspire new material.
It consumes no oil and within the last 6 moths has had one new cat.
James, you warned me and it looks like it may now be time for me to pucker up and reach for the soap. I just hope it's only one of the feckers!
What a pile of monkey metal!
In recent weeks, the very act of 'pressing on,' even under very deliberate, gradual anvil flattening, about 5-6000 revolutions dialled in and without warning - 'thud!'
Like some ruddy great limiter has suddenly called time on your romp, some kind of obvious 'limp home' mode (the car manages about 75 mph) but will not accelerate or allow cruise to be engaged.
Pull over, switch off and straight back on - sorted.
However, the regularity of this phenomenon, now of several weeks's standing, makes it very much part of the current repertoire.
It's in for a diagnostic check this Wednesday and to be honest, I cannot deny the creep of purest, Bavarian dread.
The car has a fBMWsh and only recently rendered me dangerously comparable to punters of Lamborghini Manchester insofar as the presentation of an Inspection II bill of such hurculean heft that I've only recently posted it to Frank Carson to inspire new material.
It consumes no oil and within the last 6 moths has had one new cat.
James, you warned me and it looks like it may now be time for me to pucker up and reach for the soap.
I just hope it's only one of the feckers! What a pile of monkey metal!
Hard luck mate, sounds like you know whats coming, best just to grit your teeth and take it like a man..
Sorry to hear that. Suspect the MAFs, and unless your car is under warranty then either try to clean them or replace with the VW parts that can be had for $59/piece. www.performance-cafe.com/product_info.php?products_id=787&osCsid=35111dd69928747361c7a19059cec06a
I have had two at work with similar faults that came down to 'Air Mass Meters' almost like an intermittant misfire or holding back lack of power, that left no faults in the fault memory so very difficult to diagnose.
Eventually it came to swapping parts from another car and prolonged testing as we were never sure if it was cured or just behaving itself for a while, [all this with a foreman asking if you are ready for another job yet] and Air Mass Meters did the trick.
Eventually it came to swapping parts from another car and prolonged testing as we were never sure if it was cured or just behaving itself for a while, [all this with a foreman asking if you are ready for another job yet] and Air Mass Meters did the trick.
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