Aston Martin DB9 Coil Packs – Everything you wanted to know and more

As I was preparing to replace my Spark Pugs and Coil packs (read the article here) to deal with a Lumpy Idle issue with my DB9 (read this other article here) I was researching the Coil Packs to learn if I could find a cheaper source for them.  Many of the parts in a DB9 are not bespoke, and rather scavenged from the massive Ford conglomerate parts bin.

lincoln-ls-ingnition-coil
Lincoln LS Coil Pack

Google searching this I came across several forum articles from like-minded individuals on the same search.  Some suggested that Coil Packs were the same as a Lincoln LS 3.0l V6 or a Jaguar S Type(both part of the Ford universe back in 2002-2005).  In either case, there was no certainty.  In fact, they acknowledged that the electronics were likely the same, but the ‘Boots’ that inserted into the cylinder head and internal springs connecting to the Spark Plugs were different, but you could just move the boot and spring from your old one to the new.   I was not convinced.

On top of this, there are two generations of Coil Packs for the DB9.  Early cars (MY 04 through sometime mid MY05) had 2-pin Coil Packs, and the MY06 and later cars had 3-pin (referring to the number of electrical connectors).  I have not found any clear reference to the cutover VIN number in 2005 yet.

2016-07-01 20.54.05I never found an alternate source (either a cheaper aftermarket Coil Pack made specifically for the DB9) or the exact same part sold for another car for less (the Lincoln/Jag may have been similar, but not the same).   I gave up and got the Official Aston Martin part number 4G4E-12A366-AA.  You can find them online for $66 USD each here, and I paid about £39 ($51 USD) each by contacting Rob Sims at HWM in England.  (see my article on Parts Needed to Change your Coil Packs for more details).

After I changed mine out, I decided to disassemble the old one to see if the boots/springs were easily interchangeable, and maybe this would help others find a cheaper alternative.   Below are photos and a video showing the disassembly and the result.

My Observations

  • aston-martin-db9-2-pin-coil-pack-dismantled-viewYou can remove the rubber boot from the coil pack, and this leaves a wound coil spring exposed that carries the electrical charge to the Spark Plug connection.   This spring adds some adjustability to the system.
  • aston-martin-db9-2-pin-coil-pack-dismantled-spring-with-solid-core-view-2The spring is NOT removable from the electronics head of the Coil Pack as far as I could tell.  I futzed with it significantly to try and get it disconnected, but no luck.  This would be an essential step if you were trying to reuse this portion of the old Coil Packs and marry them to a new electronics head.  If you know how to do this without cracking the whole unit open, please share the process with me.
  • aston-martin-db9-2-pin-coil-pack-dismantled-spring-with-solid-core-view-3The spring is specially wound (see the photo) and includes a special area that contains a solid metal ‘core’ that has been inserted.  This must play some important role in dampening electrical noise or assisting in transmission of the electrical charge from the Coil to the Spark Plug.

My Conclusions

Since the spring/core section is not removable, it seems that if you only interchanged the rubber boot to an alternate part from a Lincoln (that has a shorter stubby body) and maybe just ‘stretched’ the Lincolns spring to reach the same length, you’d not have the solid core or same spring setup.  This would worry me greatly that it may affect the performance of the unit in some unanticipated manner – and is not worth saving maybe $20 bucks.   It is SOOOOO hard to get in and change these rascals if you do have an issue, the savings would be false economy.
So for now, I don’t know of a better solution.  I am very interested to hear your input on this if you’ve got a better solution, or if I missed some detail here.   I would love to find an alternate source for this part that was half the price and as good or better.

Check out my video of the disassembly process here, and below are a series of High Resolution photos that might help you in this quest.


Bonus Photos

Here are some high resolution photos if you are interested in seeing the details close up.  Enjoy!

10 thoughts on “Aston Martin DB9 Coil Packs – Everything you wanted to know and more

  1. Enosh Kelley

    When using the OBD that you recommend, will you only get readings for misfires for one side of the motor?
    You mentioned how it only reads 6 cylinders, so dose it only register misfired for the side it test? Or will the misfire code be for all 12?
    Is there a way to switch it so it can read the other side as well?

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      1. Enosh Kelley

        Thank you Steve!
        Your blog has been a big help.
        I ordered a wheel from the supplier you mention. They gave me a discount and the part was shipped to Iowa in two days!
        I am thinking about doing the coil plug job myself. When I inquired about the parts they wanted to know how many pins the could have. I see that you rolled the dice and ordered two pin. I have an 06 DB9 volante. With 22k no misfire codes have ever appeared but I do have a lumpy idle. I am worried about the catalytic converters getting damaged, it doesn’t backfire either.
        Enjoy Japan. Looks like you be able to at least get to go for a ride in one while there.

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  2. Mike

    Hi, Steve. I began my coil pack project today – the disassembly phase. I have a 2006 Volante built in late 2005, so I wanted to see the coils before I ordered replacements. In case anyone cares, engine number AM04/14958 uses the THREE pin coils. I’ve emailed Rob at HWM for his best price on the coil packs, plugs, and gaskets.
    It took about 3.5 hours to get to the point of having removed the plug covers and one coil and plug (I’m leaving the others in place until the replacement parts arrive).
    I just want you to know that your nomination for sainthood is moving along nicely, and you can expect to be hearing from the Vatican any day now. I cannot imagine the terror of doing this job without your guidance. You have made it pretty much idiot-proof. Thank you so much.

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      1. Hi Enosh,
        I haven’t got an article posted about this yet (in the plans for the months ahead) but here is a link to a photo that shows it. For this photo, I have the left side Throttle Body and Intake manifold removed, but I don’t think you’ll need to take that much off. Maybe just the throttle body (which is easy – check out my other article on that). Hope this helps. https://aston1936.files.wordpress.com/2017/08/aston-martin-db9-engine-number-location.jpg

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    1. Hi Mike. Looking forward to a call from Pope Frank, he seems like a cool guy to meet! Glad the articles helped, and that you nailed down you needed 3 pin coils before you ordered. 3.5 hours is a good pace, you might get hired by AM! Good luck with the rest of the project….

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    2. Enosh Kelley

      Mike.
      Where were you able to locate the engin number?
      Steve showed me where his is but it’s seems they may have relocated it on the 2006 model.
      I also have a 2006 and and am about to do the job.
      Any info will help
      Thank you
      Enosh

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  3. Walter Stirling

    I really appreciate the excellent advice provided. My car is a 2007 DB9 coupe with sports pack and 28000 miles. I have been researching changing the auto transmission oil. ZF say change after 8 years or 50,000 miles which I think should be the definitive answer. There is a good educational video from ZF on you tube. I’m not sure how easily the fill plug is to access on a DB9. Your opinion would be helpful.
    Regards Water Stirling.

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    1. Great idea for an article, was thinking about that myself. I’d love to see the video you’ve found if you can reply and paste in the link. I know we’ll have to deal with the fluid in the Transmission Cooler lines/radiator as well, and put back the right amount and type of fluid.

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