Hi all,

I have a 2009 DB9 on 39k miles. Only had it a week or so and am trying to get my head around a few of the Aston peccadillos.

I've seen Aston1936's videos on his misfire and coil/plug changes and decided to have a look with my code reader what mine are up to.

After about 30 miles/20 minutes of driving I have between 11 - 100 misfires per cylinder. There is no loss of performance or CEL.

I'm about to go on a 3k mile road trip where I will be spanking the car for most of that distance and would like to know if I should do the coils and plugs before I go?

Does it sound like my coils are on the way out, or is the level of misfires I'm seeing on the code reader what I would get even if I replaced them?

The car has a full history but no mention of coils being done at the 7 year service.

What's you advice/experience?

Cheers

 

30-50K miles seems to be when coilpacks start dying off. Mine needed to be replaced just after 40K miles (2006 DB9). If my car was showing that number of misfires for each cylinder I'd have my coilpacks changed before the road trip.

As I understand it the problem with misfires is that unburned fuel hits your primary catalysts, burns, and degrades them by overheating. Then catalyst debris can be ingested by your engine.

 

If your having misfires with they need addressed as stated above. You will definitely do damage sooner than later to the expensive catalyst or engine which is not worth waiting for a CEL to warn you that there is something wrong. Yes it's an expensive repair to fit new ignition coils but a $40k engine plus new catalytic converters would be a total loss. Unfortunately the ignition coils are a weak point regardless of mileage but your going to do more damage if you don't repair the current issue.

 

It's time for plugs and coils ! Make sure your battery is not the original battery prior to your road trip (battery change, if done, should be noted in the history).

 

If you're going to have the coilpacks replaced, consider replacing PCV valves, injector o-rings, and spark plugs. Most of the cost is labor (labour to you), though the gaskets are pretty dear too. And don't even think about replacing one, or two, or six coilpacks -- do all of them.

 

Ok thanks everyone. I'll be replacing the lot then
I'm doing it myself so the labour cost isn't an issue, but it leads me nicely onto the next question
- which plugs do I go for? The 450hp plugs are dirt cheap, but the 470hp plugs (from what I can gather) are still only available through AM at £100+ for 4 plugs. I presume NGK supply those plugs but is there an equivalent which is available?

 

I was having misfires last year. I had my car in at a respected indy shop and he put in spark plugs. I was only a few miles from the shop when the cel came on again. It was time for winter storage so I ordered coils from Aston Bits. Even with postage, it was cheaper than I could buy them locally and they were "genuine" parts. Probably be another month until I can drive the car. Hopefully this will cure the problem.

 

hi all... what code reader can read the misfires? I have the foxwell?

 

I've got the Foxwell too. You need to do the coast down to enable the misfire detection and then its hidden in the 3rd module.

Aston1936's misfire video shows you how to find it, whatever code reader he uses has exactly the same display and menus as mine but is a different brand

 

ok great... I've looked at his website often