DB9 Plugs & Coils

[camel_landy]

I've taken the DB9 out of hibernation and on its first run out I was getting that slightly irregular and lumpy idle. The Welsh 20mph probably didn't help, so I'm hopefully going to get it on the motorway later but I suspect going to be time to change the plugs and coils.

Steve's guides (aston1936.com) are very detailed but I've got a couple of question:

1 - Are the genuine coil packs still the recommendation or is there a high quality OE alternative? (I've had to deal with 'cheap' coil packs on other cars, so not interested in it being cheap for the sake of it.)
2 - Are there any recommendations for workshops in Sth Wales? (Much as I'd like to crack on with it myself, the timing isn't great.)

M

[Dan1heMan]

I replaced the coil packs on my DB9 last year and they seem to be working fine. Mine took the 2 pin coils.

Purchased them off Autodoc, they where almost 75% cheaper than the 'Aston' alternative.

[camel_landy]

Interesting... Thanks.

Amused to see what looks like a deliberate "ERMANY" misprint, so not sure if I need to take "Manufactured for Borg Warner" with a pinch of salt too.

M

[paulrog1]

I would firstly put some fresh petrol in and go for a good run.

When were the plugs and coils last replaced?

I would take the car to a garage with AMDS, check the misfire rate.

Only the very early DB9 cars had the 2 pin coils after that 3 pin. I'm not aware of cheaper 3 pin coils but there are cheaper NGK plugs.

Edited by paulrog1 on Wednesday 4th March 12:23

[camel_landy]

New fuel done and just back from a run. It's better but Cyl5 is still reporting a misfire, requiring the clearing of a code.

Mine's a 2006 car, which sounds as though it's in the middle of the changeover period from 2x pin to 3x.

M

[8Tech]

I spoke to MSD a couple of years ago at SEMA about replacement quality coils for the DB9 but they were unable to help. It was a few years ago, probably around 2014 so dont know if they have investigated it more recently, but with the limited number of these cars in the US, and probably the world compared to the US V8's, it would probably need to be a multi fit for them to consider producing them.

I eventually bit the bullet and replaced with OEM and used the NGK plugs at a fraction of the price.

With no misfires at all on my car when replaced, just as a precautionary measure whilst installing an oil catch tank anyway, I sold my original coils for a decent price which went a fair way to paying for my new ones.

The coil failures are due to overheating in the covered plug wells and a permanent cure is to leave the covering plates off for improved cooling and substantially less heat soak. Common cure on Ford, Vauxhall and VAG inline fours. It does look a bit pants though!

Here is a link to the original post and the process involved. Quite a lengthy post, so a coffee and a sit down required....

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by 8Tech on Thursday 5th March 16:36

[camel_landy]

8Tech said:

Here is a link to the original post and the process involved. Quite a lengthy post, so a coffee and a sit down required....

Thanks... Some useful additional info there.

BTW - Did you de-pressurise the fuel rail before removal?

M

[8Tech]

From memory, I just disconnected a fuel hose or injector and wrapped a rag around the joint. very little came out because the engine had not been running for a while before I got that far so not huge pressure in there. It quickly evaporates anyway, just don't smoke whilst you do it.

I also ported the throttle bodies whilst they were off............

https://www.pistonheads.com/gassing/topic.asp?h=0&...

Edited by 8Tech on Thursday 5th March 19:29