I don't think you have a lemon. It has already 81k on it! I think it's just that time for a big maintenance job. I think GTA will fix it for you. Do do not like to lose any customers. Aston Martin Clientele is not that big so they should be working hard for you to address this problem. But when all these items are addresses i think your DB9 will last a long time before heading back into the shop. I do not care much for extended warranty. Its a lot of money IMHO. You can fix quite a bit on a car for that kind of money. After they fixed your car i would maybe just get a mechanic look your car over for the general state of it but i think you should be fine. It just sucks they sold you a car with problems, they should have fixed it before they sold it to you. But it wil get fixed and you will love the car.

 

UPDATE:

Local dealer voluntarily replaced all the coils packs and injectors, and AM HQ advised they reload software onto the car (a reboot of sorts I guess). Dealer told me car was fixed, so picked it up on Oct 21.

Drove to cottage and back that weekend, and the CEL came on again twice, with message "Emissions Service Required". The first time happened after about 50 km, with same codes... P0300, P0311 and P0316. Reset codes and then the CEL came again after another 400 km or so. Dropped the car off a few days later.

Dealer has reset codes and test drove a few cycles and says the car is fine. (I fully expect the CEL will come on again after I pick the car up at the end of the week and drive it a while). I've asked Dealer to drive it a bit more this week.

The Dealer is trying their best to resolve this but seem to be coming up short. Any suggestions? Problem codes are P0300, P0311 and P0316. I understand these are random and startup misfires, especially in #11.

Any suggestions are appreciated.

 

I had all 12 coils & plugs replaced at my dealer with parts supplied by the dealer. Within a week I was getting the same p-codes you've got.

One of the new coils was bad. Dealer replaced it (parts warranty), and all has been good since.

 

So you thing the coil in # 11 needs to be replaced?

11 was the same cylinder with the most mis-fires when this non-sense started.

 

That's what happened in my case. I'm not sure what diagnostics led them to that decision, or how often a new coil is faulty.

Seems a bit suspicious that #11 is the culprit before & after. Bad injector, faulty wiring?

 

Suspicious... agree!
They also replaced all injectors, checked wiring and compression. Maybe coil 11 needs to get replaced again.

 

The odds of it being coil 11 before and after is statistically zero. Likewise injector. It has to be a common element that was unchanged. Wiring, connector, leaky valve stem seal, etc.

 

Suggestions as to other potential causes are what I'm looking for. However, as I'm no mechanic, how would a leaky valve stem seal relate to misfires?

 

Leaky valve stem would add oil into the mix, but is easily detected. What comes to my mind first is either a faulty wire or cracked connector for that cylinder or a loose pin in the connector and it is not making a good connection to the coil (which is my guess). You can ask for suggestions all day long, but the only way to know for sure is to tear into it and see. I am about to do it for the second time, because I did not see the oil leak leak in the valve cover the first time.

 

So with leaky valve stem, I suppose the problem would be a poor gas/air mix leading to non-firing. Dealer confirmed there was no oil in spark plug wells, but I guess that's a different issue (cam cover gasket).

 

In the DB9 ODB2 diagnostics manual there are several pages on troubleshooting these codes. They cover fuel- ,ignition- ,intake- and vacuum systems. Has the dealer done this?

 

Oil from valve stem would show up as a fouled plug or at the bare minimum of oil slug on the plug.

I am not an expert, but as someone who has raced cars and had several cars over 200k miles, that is what I have seen.

 

Agaton12: Good lead! I've passed along your suggestions to the Dealer, who has also contacted AMHQ again.

Randyb: The plugs were recently changed, so don't think that's the issue.

 

Did they replace the coil connectors when they replaced the coils?
If not, IMHO coil connector for cyl #11 would be my primary target.

Hope you get this resolved and start enjoying your car soon.
I know how frustrating it can be. Hang in there.

 

Then my bet would be a broken/cracked connector or broken wire.