If your DB9 has developed a Lumpy Idle (see my in depth post on this) you’ll be faced with either taking it to the Dealership (and a $1,800+ labor bill plus parts) or undertaking the task yourself over a weekend. There is a considerable level of skill and determination required to accomplish this feat. Easily the most complicated service event I’ve done yet on my 9. If you have the gumption, tools and the time it can be a rewarding and cost saving experience. I think anyone can do it if you properly prepare.
I did a LOT of research on this prior to starting. I Googled, checked the Official Aston Martin Workshop Manual, read many forum articles of like-minded do it yourselfers, and even had a few readers of this blog send in their tips and suggestions. What you’ll be reading (and watching in the accompanying videos) is a compilation of all that advice and my own hands on experience added to it.
Forum Posts I got some background from
Credit where credit is due, I gathered background from a few others worth noting here:
Keep in mind that I don’t agree with all the things going on in all the posts, so read on to learn more.
How Aston says to do it
It would seem like Aston Martin’s official Workshop Manual would be the ultimate authority on the process, but it’s not. My opinion is that it was created by a Technical Writer (not a mechanic) who was sitting with a designer and asking “Hey, what do you have to do to change the Coils and Spark Plugs?” and the designer rattled off an answer, but didn’t actually try and do it on a real car with the engine in situ.
Regardless, here is the link to the relevant sections of the workshop manual. It’s mostly correct, but you can entirely skip the section about removing the fuel rails. I bought the special tools, and was determined to follow their guide, but it is nigh impossible to access the fuel rail connectors with the engine in the car. Even after removing the entire intake system, they are buried 8” deep under the cowl, and you’d be hard pressed to get even the smallest hands into the space, see anything, and even then manage to use the special tools to disconnect them [the photo in their manual is taken with the engine removed from the car]. Even if you got the rails decoupled, you would have to cut a series of special plastic tie-wraps to separate the electrical harness that is strapped to the fuel rails, and even then you’d still have the harness lying around. As others have documented before me, you can do it leaving the fuel rails attached, and carefully moving them aside as you complete the work. My videos will show how.
Dealer Cost to Fix
What does it cost to get this fixed at an Aston Martin Dealership? Good piece of data to know if you are weighing if its worth the bother to fix it yourself. Recently there was a 2007 DB9 sold over on www.BringATrailer.com, and the owner posted his last Dealer Service Invoice from a visit in 2020 when he had all the niggles fixed on his car. The dealership was located in Northern California (one that I’ve visited before).
They charged $2,514 USD for parts, and $1,880 USD to install them, for a total of $4,394 USD. As you’ll see below, you can do it yourself over a long weekend for less than $2,000 in parts saving yourself about $2,400.
How long will it take?
I tackled it over a long weekend. I had already ordered and received all my parts, and dedicated 4-6 hours per day to it. Having never done it before and taking the time to shoot the videos and photos definitely added to the effort. If I was asked to do it again with all the knowledge, I could knock it out in a single day (8 hours or less). A Dealer is supposed to be able to do it in 5.5 hours.
I paced myself, and broke the effort into the 3 days, tackling it in blocks:
Steve’s Guide to the Process
So here is MY summary guide to the steps you’ll want to follow. In order to make the upcoming blogs and video’s a manageable size, I have it broken down into easy to absorb smaller steps. Each post will include photos, video and all the relevant torque specs and service tips I can come up with. As I complete each blog/video I will link it here:
- Inspect your Coil Packs to find out if they are 2-pin or 3-pin
- Purchase your parts
- Gather the necessary tools
- Access the Cabin Fusebox
- Depressurize the fuel system
- Disconnect the battery
- Install Fender covers
- Remove the engine bay cross braces
- Remove the intake manifold center brace
- Disconnect the fuel rails and remove the fuel injectors
- Disconnect the ancillaries connected to the Intake Manifolds
- Remove the Intake Manifolds (including the dreaded rear bolts)
- Remove the Spark Plug Covers
- Remove the Coil Packs
- Remove the Spark Plugs
- Prepare and Install the new Spark Plugs
- Prepare and Install the new Coil Packs
- Prepare and install the Spark Plug Covers
- Remove and Replace the PCV Valves and assemblies (if you are servicing this too – recommended)
- Prepare and Install the Intake Manifolds (including gaskets)
- Prepare and Install the Fuel Injectors and Connect the Fuel Rails
- Reconnect the ancillaries to the Intake Manifolds
- Prepare and Install the Intake Manifold Center Brace
- Prepare and Install the Engine Bay Cross Braces
- Reconnect the Battery
- Restarting the Engine for the first time
And because you had the battery disconnected you will need to:
- Recalibrate the Door Window Glass Auto Drop Positioning
- Calibrate the Seat Modules
- Set the Clock
- Relearn the Misfire Correction Factors. This is the final and important step necessary since the old calibration would be lost with the battery disconnect, and needed to be redone anyways since you’ve changed the Coils and Plugs and the correction factors need updated. If you skipped my advice and left the battery connected, you will need to head to the dealer to ask (a.k.a pay) them to use their AMDS system to tell the system to relearn the correction factors, and hence I think you should just disconnect the battery and let the system dump the old ones when the memory is lost.
I hope you enjoy the series of blogs and videos that follow next. To aid in this I have created a YouTube Playlist that links all the related videos together into a single channel, and they will play in order of how to do the entire project. Enjoy!