Aston Martin Misfire and "Emission System Service Required"
Discussion
Hello, I'm new to the forum having purchased an Aston Martin DB9 2005 (34,860miles) earlier in the year and it has recently developed a misfire along with now I also get an "Emission System Service Required" warning. Are the two directly related? my guess is yes ! The misfire started a couple of weeks before the Emission warning.
I have checked the misfire with my OBDII tester and I get the following number of misfires over a short period of time :- Cyl 1, 7; Cyl 2, 0; Cyl 3, 651; Cyl 4, 1; Cyl 5, 6; Cyl 6, 4; Cyl 7, 9; Cyl 8, 2; Cyl 9, 105; Cyl 10, 88; Cyl 11, 14; Cyl 12, 11.
Clearly the main offender is Cyl 3 with 651 misfires the tester says "Cyl 3 misfire", but Cyl 9 and Cyl 10 also look to be starting to fail although the tester doesn't flag them up ..... yet ! Does anyone know what is the maximum number of misfires that is considered "acceptable" before action is needed.
As other DB9 DIY owners will know the work is extensive to replace the plugs and coil packs as half of the engine disappears under the passenger compartment and getting the air intake manifolds off is quite a challenge not to mention getting the plugs out of cyls 6 & 7.
I plan to change the spark plugs and coil packs on Cyls 3 and as a precaution 9 & 10. Since the other cylinder misfires are low I'm torn with the thought that I should replace them all while it's stripped down but that's not cheap !!! I have to spend £225 for the two inlet manifold gaskets but then a plug and coil pack costs £15-20 and £65 respectively so its circa £80 a pop !!! .... £960 for a full set !!! still you don't buy a DB9 expecting it to be cheap when things go wrong.
I've checked out Steve's work on Aston1936.com and it seems quite straight forward albeit access is a bit of a nightmare.
Any thoughts anyone ...... do I go with just the three cylinders or is it the full monty ???
Thanks,
Mike
I have checked the misfire with my OBDII tester and I get the following number of misfires over a short period of time :- Cyl 1, 7; Cyl 2, 0; Cyl 3, 651; Cyl 4, 1; Cyl 5, 6; Cyl 6, 4; Cyl 7, 9; Cyl 8, 2; Cyl 9, 105; Cyl 10, 88; Cyl 11, 14; Cyl 12, 11.
Clearly the main offender is Cyl 3 with 651 misfires the tester says "Cyl 3 misfire", but Cyl 9 and Cyl 10 also look to be starting to fail although the tester doesn't flag them up ..... yet ! Does anyone know what is the maximum number of misfires that is considered "acceptable" before action is needed.
As other DB9 DIY owners will know the work is extensive to replace the plugs and coil packs as half of the engine disappears under the passenger compartment and getting the air intake manifolds off is quite a challenge not to mention getting the plugs out of cyls 6 & 7.
I plan to change the spark plugs and coil packs on Cyls 3 and as a precaution 9 & 10. Since the other cylinder misfires are low I'm torn with the thought that I should replace them all while it's stripped down but that's not cheap !!! I have to spend £225 for the two inlet manifold gaskets but then a plug and coil pack costs £15-20 and £65 respectively so its circa £80 a pop !!! .... £960 for a full set !!! still you don't buy a DB9 expecting it to be cheap when things go wrong.
I've checked out Steve's work on Aston1936.com and it seems quite straight forward albeit access is a bit of a nightmare.
Any thoughts anyone ...... do I go with just the three cylinders or is it the full monty ???
Thanks,
Mike
Edited by 8436mike on Thursday 27th July 11:15
Hi Flugplatz,
I'm hoping that once I change the three plugs and coil packs on cyls 3, 9 & 10, that I know I have to do (if not all 12 cyls), then that should stop any unburnt fuel going through the O2 sensors triggering the fault and all will then be OK !!! If I still have a problem I will then look to the O2 sensors first and hopefully not the cats.
Thanks for your reply,
Mike
I'm hoping that once I change the three plugs and coil packs on cyls 3, 9 & 10, that I know I have to do (if not all 12 cyls), then that should stop any unburnt fuel going through the O2 sensors triggering the fault and all will then be OK !!! If I still have a problem I will then look to the O2 sensors first and hopefully not the cats.
Thanks for your reply,
Mike
I would do all 12 whilst you have the inlets off. The others may be on their way out.
Plugs are not that expensive if you source them from non aston dealer likewise the coils.
They are jaguar 3.0 v6 coils with a longer boot. Just reuse the old boots. Search on the web for further info.
Plugs are not that expensive if you source them from non aston dealer likewise the coils.
They are jaguar 3.0 v6 coils with a longer boot. Just reuse the old boots. Search on the web for further info.
You can change one bank at a time, since the common labor is not that great. But if you need to change coils on both banks, DO ALL 12 !!!
Manifold gaskets are certainly reusable after a close inspection. So, if you can wait, then look at them before ordering new ones. My old ones looked no different than the new ones...what a waste of money.
Buy your plugs from your local auto parts store.
Manifold gaskets are certainly reusable after a close inspection. So, if you can wait, then look at them before ordering new ones. My old ones looked no different than the new ones...what a waste of money.
Buy your plugs from your local auto parts store.
Same symptoms on my 2005 DB9. New coil packs and plugs (all 12) sorted it. If you going to go through the pain of accessing a few of them then do all 12 at the same time. Do you want to have to do the rest in a few months?
Can you see from the service history if they have been done at all ? If not then circa 40k miles seems about right for a new set of coils.
Can you see from the service history if they have been done at all ? If not then circa 40k miles seems about right for a new set of coils.
Hello to all who have responded and thanks,
I really appreciate the input from you all ....... I know it makes sense but the thought of dumping 9 working coils (all be it only for now) sticks in the craw a bit !!!
I've another question now and one that I've seen bantered around a bit with no real outcome that I have found [other than a bit of P1ss taking about left / right; offside / nearside; port / starboard !@*?] ... how are the cylinders numbered???
Option 1 - Logic says working along the crank shaft from front to back ...
Windscreen
11 12
9 10
7 8
5 6
3 4
1 2
Front of car looking
into engine radiator
this end !!!
Option 2 - but I've seen it like this.....
Windscreen
6 12
5 11
4 10
3 9
2 8
1 7
Front of car looking
into engine radiator
this end !!!
Option 2 - and I've seen it like this.....
Windscreen
6 7
5 8
4 9
3 10
2 11
1 12
Front of car looking
into engine radiator
this end !!!
I've got a downloaded DB9 manual and have trawled through it trying to find this answer but nothing !!!
Anyone know for sure ????
Thanks,
Mike
I really appreciate the input from you all ....... I know it makes sense but the thought of dumping 9 working coils (all be it only for now) sticks in the craw a bit !!!
I've another question now and one that I've seen bantered around a bit with no real outcome that I have found [other than a bit of P1ss taking about left / right; offside / nearside; port / starboard !@*?] ... how are the cylinders numbered???
Option 1 - Logic says working along the crank shaft from front to back ...
Windscreen
11 12
9 10
7 8
5 6
3 4
1 2
Front of car looking
into engine radiator
this end !!!
Option 2 - but I've seen it like this.....
Windscreen
6 12
5 11
4 10
3 9
2 8
1 7
Front of car looking
into engine radiator
this end !!!
Option 2 - and I've seen it like this.....
Windscreen
6 7
5 8
4 9
3 10
2 11
1 12
Front of car looking
into engine radiator
this end !!!
I've got a downloaded DB9 manual and have trawled through it trying to find this answer but nothing !!!
Anyone know for sure ????
Thanks,
Mike
No idea about numbering of the cylinders. But to get back to the coils....the reason they have a 40k-ish lifespan is that they sit in the V and get exposed to very high temperatures. I know you may think it makes sense to only replace the failing ones, but the rest will go west sooner rather than later
I did this recently as a preventative measure at 40,000m and replaced all 12 coils and plugs when I installed the breather catch can.
Thats a lot of work, and those manifold gaskets are not cheap, to guess which coils are already playing up without replacing the rest.
I have been advised by MSD in the US that the spring in the boot is the major cause of the coil failures as well as the heat so if replacing them, then I would not advise reinstalling the old boots.
There is one manufacturer who replaces the boots and spring with a solid conductor for a positive connection.
Thats a lot of work, and those manifold gaskets are not cheap, to guess which coils are already playing up without replacing the rest.
I have been advised by MSD in the US that the spring in the boot is the major cause of the coil failures as well as the heat so if replacing them, then I would not advise reinstalling the old boots.
There is one manufacturer who replaces the boots and spring with a solid conductor for a positive connection.
8Tech said:
I did this recently as a preventative measure at 40,000m and replaced all 12 coils and plugs when I installed the breather catch can.
Thats a lot of work, and those manifold gaskets are not cheap, to guess which coils are already playing up without replacing the rest.
I have been advised by MSD in the US that the spring in the boot is the major cause of the coil failures as well as the heat so if replacing them, then I would not advise reinstalling the old boots.
There is one manufacturer who replaces the boots and spring with a solid conductor for a positive connection.
Thanks for the info.Thats a lot of work, and those manifold gaskets are not cheap, to guess which coils are already playing up without replacing the rest.
I have been advised by MSD in the US that the spring in the boot is the major cause of the coil failures as well as the heat so if replacing them, then I would not advise reinstalling the old boots.
There is one manufacturer who replaces the boots and spring with a solid conductor for a positive connection.
Do you have any alternative suppliers for the coils other than the main dealer?
Yes Option 2.
I've done this job on my Vanquish and the gaskets were still reusable. The plugs can be bought cheaply on the net and I havent seen any alternative but AM for the coils. Best place for the coils I found to be HWM.
It's a big job, you will really kick yourself if you only change a few and have another misfire a week later (and yes from what you describe it certainly is time to do something about it or you will have your cats failing next, getting sucked into the engine, resulting in a very major bill). I did all 12 plugs and coils, it will be a long day!
Have a look through the Bamford Rose sticky if you want to see what happens when the engine eats tha cats.
I've done this job on my Vanquish and the gaskets were still reusable. The plugs can be bought cheaply on the net and I havent seen any alternative but AM for the coils. Best place for the coils I found to be HWM.
It's a big job, you will really kick yourself if you only change a few and have another misfire a week later (and yes from what you describe it certainly is time to do something about it or you will have your cats failing next, getting sucked into the engine, resulting in a very major bill). I did all 12 plugs and coils, it will be a long day!
Have a look through the Bamford Rose sticky if you want to see what happens when the engine eats tha cats.
Edited by F1NDW on Friday 28th July 05:23
Again thanks to all for the replies,
I've come down on the side of replacing them all ..... you know it makes sense ...... approach, besides I don't think I can be confident about which are the offending cylinders 3, 9 & 10 despite the consensus being that it is my Option 2 for the cylinder numbering and I have no idea how to test a coil once I have got it out of the engine to make sure.
Appreciate the comments about the heat being an issue affecting the coil pack life they are certainly in the heart of the engine and with a cover plate over them as well. Perhaps the cover plate should have been a mesh or even not there at all to allow better heat dissipation. I certainly see a heat haze over the bonnet (hood for you over the pond) when sat in traffic but the temp gauge sits right in the middle (normal).
Thanks to all again I'll post another comment when I've done the job ... just off to find my wife's credit card !!!
Mike
I've come down on the side of replacing them all ..... you know it makes sense ...... approach, besides I don't think I can be confident about which are the offending cylinders 3, 9 & 10 despite the consensus being that it is my Option 2 for the cylinder numbering and I have no idea how to test a coil once I have got it out of the engine to make sure.
Appreciate the comments about the heat being an issue affecting the coil pack life they are certainly in the heart of the engine and with a cover plate over them as well. Perhaps the cover plate should have been a mesh or even not there at all to allow better heat dissipation. I certainly see a heat haze over the bonnet (hood for you over the pond) when sat in traffic but the temp gauge sits right in the middle (normal).
Thanks to all again I'll post another comment when I've done the job ... just off to find my wife's credit card !!!
Mike
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