When is a misfire not a misfire?
Discussion
Readers may remember that about six months ago my newly-bought 14K mile 2007 DB9 with full AMSH was stuttering when accelerating from low revs when warm. The first reaction with the V12 always seems to be 'Misfire, coilpacks and plugs, or you will destroy the cats and then the engine, don't drive it'. As you can imagine this caused a great deal of concern, not least as this was supposed to be the pinnacle of my motoring aspirations.
At this point the supplying indy dealer stopped responding, so, as I needed to get the car fixed without delay, I resolved to get it done elsewhere and then make a claim. The car (which according to the dealer had new coilpacks and plugs six months before), was trailered off to a well known Aston independent. They had, they told me, all the special software, and 75 years' experience, and could see the car the next day. Excellent!
The plan fell apart when the well-known Aston independent with all the special software and 75 years' experience could find no codes nor any cylinder misfire data. And so they proceeded - with my approval as I trusted them - to take the engine apart bit by bit. First the induction side... looks OK, £150 for a smoke test, seems OK, let's take an inlet manifold off, £450 I'm afraid sir, new gasket of course, £120 + VAT, only come in pairs you know, hmm the coilpacks look OK but you never know, can't test them... oh hang on this coilpack clip is broken, that might be it, we can fit a new one for £79, after all sir a new loom would be £4,000... actually what we should do next is change the spark plugs, £288 and see if that fixes it.'
At this point I realised I was paying them good money for no more than guesswork, called them off and retrieved the car. A kindly forum member lent me his Foxwell, which I took round to my friendly local mechanic, and two misfiring cylinders were found. The offending coilpacks and plugs were replaced, and the misfires were fixed, but the stutter was still there. Bugger. But it shows that a Foxwell in competent hands beats a monkey with AMDS.
Some time later I happened to be in Halfords. An assistant came up and asked if he could help. 'Well maybe, if you know anything about Aston Martins?' 'Well yes sir, our service manager used to work for them!'. So I had a good chat with the service manager, who told me he'd helped develop the V12 engine software (scoop!), and took him for a test drive. He said 'Yes definitely a misfire'. He said he had a laptop with all the software needed, but it was with a friend and he'd have to borrow it back... the weeks went by, no laptop. But he did mention a place in Colchester that did diagnostics.
So I gave up on the man with the imaginary laptop and went to the place in Colchester. The boss got on the case and after several hour's testing concluded that the car needed a new torque converter for £5,000 + VAT. That was game over. I forwarded his report to the supplying dealer and told him I wanted to reject the car. This time I got a reply straight back offering to take the car back and fix it. But he didn't believe it was the torque converter, and neither did the Aston specialist he took it to. 'Hmm no can't be the torque converter, never known of of those to go in all the 15 years I've been working with Astons'. But he had AMDS, and unlike the first lot, knew how to work it. It was indeed the torque converter. The oil was found to be very dark and a litre low. An oil and filter change didn't fix the stutter so it was gearbox-out time...
Last Saturday, after eight weeks away, my DB9 came back. And now it works as it should do. For the first time, I can accelerate without worrying that I might be destroying the cats and the engine. I can now, at last, start to enjoy my first Aston, and everything works perfectly.
Looking back:
I hear that the official Aston Martin line is that the gearbox is 'sealed for life'. The main dealer who serviced the car every year 2007-2020 recommend it's changed at 40K miles. My car fell through the gap because it was far short of 40K miles. Had the dealer changed the oil after, say 10 years, very probably all the above would never have happened.
So the lessons are:
1) Not everything is a misfire, despite it being the go-to answer for the V12.
2) Just because you have AMDS doesn't mean you can fix things.
3) Change the gearbox oil by time as well as mileage.
Of the first 'Aston specialist', a polite letter pointing out that they'd been looking at the wrong end of the car received no reply; Section 75 recovered my money.
One name I can mention, because they did a brilliant job and unlocked the riddle of the stuttering Aston, is Fairfax Motors in Colchester. Not 'Aston specialists', no AMDS, but one bloke with shedloads of practical experience and brains (there were two Bentley W12s outside so he evidently has a reputation!).
Edited to say 'The main dealer who serviced the car every year 2007-2020' not 2007-2014...
At this point the supplying indy dealer stopped responding, so, as I needed to get the car fixed without delay, I resolved to get it done elsewhere and then make a claim. The car (which according to the dealer had new coilpacks and plugs six months before), was trailered off to a well known Aston independent. They had, they told me, all the special software, and 75 years' experience, and could see the car the next day. Excellent!
The plan fell apart when the well-known Aston independent with all the special software and 75 years' experience could find no codes nor any cylinder misfire data. And so they proceeded - with my approval as I trusted them - to take the engine apart bit by bit. First the induction side... looks OK, £150 for a smoke test, seems OK, let's take an inlet manifold off, £450 I'm afraid sir, new gasket of course, £120 + VAT, only come in pairs you know, hmm the coilpacks look OK but you never know, can't test them... oh hang on this coilpack clip is broken, that might be it, we can fit a new one for £79, after all sir a new loom would be £4,000... actually what we should do next is change the spark plugs, £288 and see if that fixes it.'
At this point I realised I was paying them good money for no more than guesswork, called them off and retrieved the car. A kindly forum member lent me his Foxwell, which I took round to my friendly local mechanic, and two misfiring cylinders were found. The offending coilpacks and plugs were replaced, and the misfires were fixed, but the stutter was still there. Bugger. But it shows that a Foxwell in competent hands beats a monkey with AMDS.
Some time later I happened to be in Halfords. An assistant came up and asked if he could help. 'Well maybe, if you know anything about Aston Martins?' 'Well yes sir, our service manager used to work for them!'. So I had a good chat with the service manager, who told me he'd helped develop the V12 engine software (scoop!), and took him for a test drive. He said 'Yes definitely a misfire'. He said he had a laptop with all the software needed, but it was with a friend and he'd have to borrow it back... the weeks went by, no laptop. But he did mention a place in Colchester that did diagnostics.
So I gave up on the man with the imaginary laptop and went to the place in Colchester. The boss got on the case and after several hour's testing concluded that the car needed a new torque converter for £5,000 + VAT. That was game over. I forwarded his report to the supplying dealer and told him I wanted to reject the car. This time I got a reply straight back offering to take the car back and fix it. But he didn't believe it was the torque converter, and neither did the Aston specialist he took it to. 'Hmm no can't be the torque converter, never known of of those to go in all the 15 years I've been working with Astons'. But he had AMDS, and unlike the first lot, knew how to work it. It was indeed the torque converter. The oil was found to be very dark and a litre low. An oil and filter change didn't fix the stutter so it was gearbox-out time...
Last Saturday, after eight weeks away, my DB9 came back. And now it works as it should do. For the first time, I can accelerate without worrying that I might be destroying the cats and the engine. I can now, at last, start to enjoy my first Aston, and everything works perfectly.
Looking back:
I hear that the official Aston Martin line is that the gearbox is 'sealed for life'. The main dealer who serviced the car every year 2007-2020 recommend it's changed at 40K miles. My car fell through the gap because it was far short of 40K miles. Had the dealer changed the oil after, say 10 years, very probably all the above would never have happened.
So the lessons are:
1) Not everything is a misfire, despite it being the go-to answer for the V12.
2) Just because you have AMDS doesn't mean you can fix things.
3) Change the gearbox oil by time as well as mileage.
Of the first 'Aston specialist', a polite letter pointing out that they'd been looking at the wrong end of the car received no reply; Section 75 recovered my money.
One name I can mention, because they did a brilliant job and unlocked the riddle of the stuttering Aston, is Fairfax Motors in Colchester. Not 'Aston specialists', no AMDS, but one bloke with shedloads of practical experience and brains (there were two Bentley W12s outside so he evidently has a reputation!).
Edited to say 'The main dealer who serviced the car every year 2007-2020' not 2007-2014...
Edited by Simpo Two on Saturday 4th June 12:35
It's good to hear your problem was solved by changing the torque converter, but what was wrong with it? Presumably something to do with a lock-up clutch but why would that only show up under acceleration? Maybe it was simply slipping under high torque conditions - hence no codes. (The classic way to detect a weak clutch in a manual car is to accelerate from low speed in 3rd gear.) As you discovered, lockup clutch slip can feel like a misfire and will trigger no codes. It can also "look" like a misfire on the rev-counter because engine rpm will fluctuate slightly as the driveline slips and grips.
How many miles did you put on the car between the fluid change and eventual TQ replacement? I only ask because the clutches in an auto are "wet" and the friction surface is impregnated with whatever fluid is in the transmission. After a fluid change it can take perhaps 300 miles for the new fluid to fully displace that old fluid in/on the friction material.
In an auto the fluid is very much an integral part of the transmission and not just a lubricant in which the gears operate. It's interesting that yours was very dark. If it had a nasty burnt smell as well that would be the classic sign of an overheated transmission. If it was simply discoloured then the colour is likely to be fragments of clutches and bands worn off by friction. Quite possibly your lock-up clutch.
The mystery remains why this should have happened to your car if it's not a common problem with the model.
How many miles did you put on the car between the fluid change and eventual TQ replacement? I only ask because the clutches in an auto are "wet" and the friction surface is impregnated with whatever fluid is in the transmission. After a fluid change it can take perhaps 300 miles for the new fluid to fully displace that old fluid in/on the friction material.
In an auto the fluid is very much an integral part of the transmission and not just a lubricant in which the gears operate. It's interesting that yours was very dark. If it had a nasty burnt smell as well that would be the classic sign of an overheated transmission. If it was simply discoloured then the colour is likely to be fragments of clutches and bands worn off by friction. Quite possibly your lock-up clutch.
The mystery remains why this should have happened to your car if it's not a common problem with the model.
My own rule of thumb regarding "sealed for life TQ autos" is to have a precautionary fluid replacement at the earlier of 10 years or 100,000 miles. I'm not saying 40,000 is wrong but if that amounted to a change every 3 years it looks over eager. The fluid in an auto should have a much easier life than, for instance, engine oil which is exposed to heat, condensation, combustion products and unburnt fuel.
2 things
1. I am glad your all sorted and that you are now enjoying aston life for the summer
2. I am glad you shared your experiences.
All of us with V12s can face these non standard issues at anytime and it's always useful to be able to learn from others misfortunes. Information is key and it's easy to get sucked in by the supposed specialists telling you it might be this it might be that all the while a big bill is piling up in the corner.
Cheers and happy motoring
1. I am glad your all sorted and that you are now enjoying aston life for the summer
2. I am glad you shared your experiences.
All of us with V12s can face these non standard issues at anytime and it's always useful to be able to learn from others misfortunes. Information is key and it's easy to get sucked in by the supposed specialists telling you it might be this it might be that all the while a big bill is piling up in the corner.
Cheers and happy motoring
chrisbolton said:
Really glad to hear your are all sorted and able to enjoy the car properly now.
Thanks Chris, and honoured that you spent only your 7th post in 12 years on me 
Panamax said:
It's good to hear your problem was solved by changing the torque converter, but what was wrong with it? Presumably something to do with a lock-up clutch but why would that only show up under acceleration? Maybe it was simply slipping under high torque conditions - hence no codes. (The classic way to detect a weak clutch in a manual car is to accelerate from low speed in 3rd gear.) As you discovered, lockup clutch slip can feel like a misfire and will trigger no codes. It can also "look" like a misfire on the rev-counter because engine rpm will fluctuate slightly as the driveline slips and grips.
That would make sense to me. To be frank I know very little about TCs and I don't think the dealer does either - which is fair enough as his interest is to sell cars not be an engineer.Panamax said:
How many miles did you put on the car between the fluid change and eventual TQ replacement? I only ask because the clutches in an auto are "wet" and the friction surface is impregnated with whatever fluid is in the transmission. After a fluid change it can take perhaps 300 miles for the new fluid to fully displace that old fluid in/on the friction material.
I didn't have the car then; the second specialist did that (Phoenix AM in Basingstoke). The oil/filter were changed first as a 'possible cheap fix if lucky' - I was just informed that it hadn't worked. Rather than pay a high labour rate the the dealer took the car back and got his in-house chap to do the TC change. I wasn't entirely happy with that but it was out of my hands, and ultimately it seems he did OK..Panamax said:
In an auto the fluid is very much an integral part of the transmission and not just a lubricant in which the gears operate. It's interesting that yours was very dark. If it had a nasty burnt smell as well that would be the classic sign of an overheated transmission. If it was simply discoloured then the colour is likely to be fragments of clutches and bands worn off by friction. Quite possibly your lock-up clutch.
The mystery remains why this should have happened to your car if it's not a common problem with the model.
The only suggestion was deterioration due to age, which then perhaps damaged the TC somehow. I don't go anywhere near the red-line but could it have happened as a result of somebody caning the nuts off it at some time?The mystery remains why this should have happened to your car if it's not a common problem with the model.
Longy00000 said:
2 things
1. I am glad your all sorted and that you are now enjoying aston life for the summer
2. I am glad you shared your experiences.
All of us with V12s can face these non standard issues at anytime and it's always useful to be able to learn from others misfortunes. Information is key and it's easy to get sucked in by the supposed specialists telling you it might be this it might be that all the while a big bill is piling up in the corner.
Cheers and happy motoring
Thank you 1. I am glad your all sorted and that you are now enjoying aston life for the summer
2. I am glad you shared your experiences.
All of us with V12s can face these non standard issues at anytime and it's always useful to be able to learn from others misfortunes. Information is key and it's easy to get sucked in by the supposed specialists telling you it might be this it might be that all the while a big bill is piling up in the corner.
Cheers and happy motoring
Thank you for telling us about the actual fault.
What a nightmare!
So disappointing that it occurred immediately following the purchase of your (I think first) Aston Martin.
It was your perseverance which eventually achieved success. Many of us would have probably given up during that saga.
Our initial references to you about V12 misfires and the very rare consequential engine disasters, were to make sure that you knew about that possibility. I don't recall any mention here about auto gearbox failures, hence no one commented about that.
I have experienced torque converter low oil level (not Aston Martin), but my symptoms were dive slip and failure to change gear properly. That difficulty was quickly resolved by an oil and filter change.
Very pleased to know that you can now enjoy your Aston Martin.
Jon39 said:
Thank you for telling us about the actual fault.
What a nightmare!
So disappointing that it occurred immediately following the purchase of your (I think first) Aston Martin.
It was your perseverance which eventually achieved success. Many of us would have probably given up during that saga.
Our initial references to you about V12 misfires and the very rare consequential engine disasters, were to make sure that you knew about that possibility. I don't recall any mention here about auto gearbox failures, hence no one commented about that.
I have experienced torque converter low oil level (not Aston Martin), but my symptoms were dive slip and failure to change gear properly. That difficulty was quickly resolved by an oil and filter change.
Very pleased to know that you can now enjoy your Aston Martin.
It was and indeed is my first one What a nightmare!
So disappointing that it occurred immediately following the purchase of your (I think first) Aston Martin.
It was your perseverance which eventually achieved success. Many of us would have probably given up during that saga.
Our initial references to you about V12 misfires and the very rare consequential engine disasters, were to make sure that you knew about that possibility. I don't recall any mention here about auto gearbox failures, hence no one commented about that.
I have experienced torque converter low oil level (not Aston Martin), but my symptoms were dive slip and failure to change gear properly. That difficulty was quickly resolved by an oil and filter change.
Very pleased to know that you can now enjoy your Aston Martin.
The car actually had the fault when I bought it, but because it wasn't evident until after 25-30 minutes it didn't show up on the test drive. To begin with I assumed/hoped it was a bit of crud somewhere in the fuel that would clear.
I did, as you saw, eventually want to reject the car, but the dealer had a right to try to fix it, and eventually he did. While it was away he lent me a remarkably competent Mercedes E300 AMG-Line convertible, and then another Merc, albeit rather a dog, when the lease expired on the first one. If I had to have a 'normal' car then the E300 'vert could well be it. (A four seat convertible with good luggage space AND folding rear seats! Why couldn't Aston Martin design such a thing?) And the Mercs were half the price to feed than the DB9 so good things can always be extracted from disaster.
Re misfires, it seemed to be a generally held view rather than any one person, and aided by a certain gentleman's videos of doom and destruction (and to those placing bets on when my engine would blow up, I'm afraid you lost your stake). The other oddity was a sudden very loud buzz that emanated from somewhere under the car when cruising. I've only done 180 miles since the car came back but so far it hasn't buzzed, so hopefully that was related. Can a knackered TC buzz?
Scrump said:
Pleased for you that it is now sorted. I followed your earlier posts about the saga of the coil packs with some interest and although I didn’t comment I was hoping you quickly found a fix.
Thanks very much - yes, all it needed was one competent person, and eventually I found one.Simpo Two said:
... While it was away he lent me a remarkably competent Mercedes E300 AMG-Line convertible, and then another Merc, albeit rather a dog, when the lease expired on the first one. If I had to have a 'normal' car then the E300 'vert could well be it. (A four seat convertible with good luggage space AND folding rear seats! Why couldn't Aston Martin design such a thing?) And the Mercs were half the price to feed than the DB9, so good things can always be extracted from disaster. ...
Interesting that the car won you over. My current Mercedes (not half as much fun as my Aston Martin) is a 3.2 V6 petrol Coupe, that has remarkably provided reliable transport for over 20 years. Still perfect, although don't want to push luck too far, but it has encouraged me to stay loyal to the brand.
There is an all new replacement for the current E-class, expected next year, so that is on my short list. They depreciate like a dropped stone, but what the heck. Probably will be the very last IC engine version. There is a (think) 48 volt battery powered motor in line with the engine, which is used just to fill in for turbo lag. Having heard about an E-class hybrid being scrapped, following battery failure at 8 years old, I want others to experiment with this new electric revolution before me.
Edited by Dewi 2 on Saturday 4th June 19:38
Dewi 2 said:
Having heard about an E-class hybrid being scrapped, following battery failure at 8 years old, I want others to experiment with this new electric revolution before me.
I wouldn't be at all surprised if in 20 years' time the ecomentalists are whining about all the toxic metals from old batteries piled up in fields and the destruction caused by digging them up in the first place. But electricity is the new religion so we have to go along with it.I have nothing against EVs per se; indeed an electric motor with two wires and one moving part seems vastly more appealing than the V12. When they make an EV I want to buy, and it is affordable, I might get one. We shall see...
Oh and please can somebody make an actual Grand Tourer? Something distinctive that can get me to St Tropez in comfort, in style, with luggage, and with more than 18mpg?
There's a great article here on the autobox fitted to the early DB9's
https://aston1936.com/2018/12/23/the-aston-martin-...
https://aston1936.com/2018/12/23/the-aston-martin-...
vulcan26 said:
There's a great article here on the autobox fitted to the early DB9's
https://aston1936.com/2018/12/23/the-aston-martin-...
Thanks; yes that seems to match up with what shreds of info I've picked up along the way.https://aston1936.com/2018/12/23/the-aston-martin-...
'...or after eight years at the latest'. I would agree, and am inclined to pass that to the main dealer who looked after it until 2020 (who went suddenly quiet when I suggested that the oil has a service life in years as well as mileage).
One thing - the dealer said he wasn't going to use AM branded oil because it would cost £450. He used Jaguar oil instead as that was only £50, he said. If it is the same stuff, it's a salutary tale that sometimes 'The Badge' means 'I saw you coming'. If it isn't the same stuff, I can expect the gearbox to explode next week...
PS As for the diff service, why would that need doing every two years? None of my other cars seem to have needed it.
Edited by Simpo Two on Sunday 5th June 18:37
Thanks folks, I really appreciate your support. It wasn't an easy period, not least because one takes the evidence available, weighs it up, makes a logical decision, then it turns out to be wrong. The AM independent who promised all but couldn't get a misfire count and started dismantling the wrong end of the car. The former AM boff who promised all but never delivered. But then there were the good guys: Ian with the Foxwell, Jon with the spanners, James with the diagnostics, Andrew who confirmed it, and finally the supplying dealer who took the car back and (we hope!) fixed it. The car you buy because you intend to love it, that turns into a car you never want to see again, then back the other way...
@paulrog1 I hope you get your P&J back all fixed too
@paulrog1 I hope you get your P&J back all fixed too
Simpo Two said:
One thing - the dealer said he wasn't going to use AM branded oil because it would cost £450. He used Jaguar oil instead as that was only £50, he said. If it is the same stuff, it's a salutary tale that sometimes 'The Badge' means 'I saw you coming'. If it isn't the same stuff, I can expect the gearbox to explode next week.
That's a bit cheeky. As I alluded to above transmission fluid is often very model specific being part of the transmission's engineering and not just a lubricant. Keep those fingers crossed.Panamax said:
Simpo Two said:
One thing - the dealer said he wasn't going to use AM branded oil because it would cost £450. He used Jaguar oil instead as that was only £50, he said. If it is the same stuff, it's a salutary tale that sometimes 'The Badge' means 'I saw you coming'. If it isn't the same stuff, I can expect the gearbox to explode next week.
That's a bit cheeky. As I alluded to above transmission fluid is often very model specific being part of the transmission's engineering and not just a lubricant. Keep those fingers crossed.Once the probem was diagnosed Phoenix changed the oil, which I presume was the £450 version. But it didn't work so then the TC had to be changed. I wonder what happened to all that new oil? It would have been contaminated of course, so maybe binned. An expensive guess.
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