Hey Bud, I was looking at this and don't mean to bring a thread back from the grave..but was wondering if you every resolved this concern...did you feel a misfire??..and was your clutch ever replaced??

BTW: Check Engine light/Emissions light is "not" a normal thing..this is when vehicle runs in open loop and does "not" operate correctly.

 

For the last couple of months it was fine. No more check engine light, tho there are still two error messages about the misfire in the ODB scan. I will have to replace the ignition coils and sparks for these two cylinders as well.

I am not aware my clutch has been replaced, but I never had issues with my clutch tho. Why where you asking?

J

 

If the misfire corrections are not stored...or the clutch was replaced along with the flywheel and the misfire corrects were not cleared and then relearned..this will store a misfire code even though there is no misfire occurring..the triggers are on the flywheel and if a new flywheel is fitted, the adaptations from the old one are used if not cleared..if the new flywheels triggers are off by even 1/32 of an inch..the PCM thinks the engine is misfiring and stores a code. Same goes for if the misfire corrects are never stored/learned(possibly your case). If they are never stored the PCM cannot detect a misfire correctly and diagnosics can lead to the incorrect part being replaced/diagnosed.

 

I am not sure if I understood everything , but I will check on the clutch replacement. Thanks for the input.

 

hehe.."misfire corrections" is something that needs to be reset with Aston Martin AMDS computer which is what teh dealership uses to diagnose faults..the misfire corrections can "ONLY" be rest with AMDS, a battery hard reset does not do this for the PCM stores these misfire corrections in it's memory..

To relearn the misifre correction..the dealer will need to erase the stored corrections with AMDS..then perform a step-by-step road test at certain speeds to have the PCM store it's new misfire corrections(a.k.a it's 36-1 points)..

If none of this has been done during a clutch replace..or say the clutch wasn't replaced and the vehicle never had the misfire corrections stored/learned..a misfire can be triggered by the PCM even though nothing is wrong ..*PCM looks for number, anything out side this range reflects to a fault if the PCM cannot correct the range to get these number back to spec range..thus the MIL light comes on**

 

Do I take it that if a coil or 2 goes bad its worth replacing all 8 coils?

That would make sense imo. Especially since the others with similiar wear and tear maybe close to the end of their useful life?

 

Depending on the mileage and model..if the car has 200km and a coil took the boot..just the coil and plug unless there was a defect noted and ID of coils are in that range then all coils should be replaced...if car has 50,000km and 1 coil is acting up..that one coil should be swapped with another and checked for the other cyl to misfire..if the same cyl misfires with another known working coil..fault is not with the coil..(this cannot be done on oler V12's like Vanquish and DB7)

When a mechanic recommends to replace all the coils because 1 stopped..it's usually because of the mileage or labour involved...on a V8V or DB9 I just change the faulty coil and plug(there simple and easy to replace)..on a Vanquish/DB7 which you need to remove the entire upper intake manifold..it's not worth changing just 1 coil because of the labour involved so all are replaced..

Vanquish/DB7 are known for coils, plugs, and misfire module..V8V's and DB9's are not.

*This is only based on what I've seen, and also heard from other tech's at training events..*

 

Now, I'm not questioning you on this, it is true. But man if can show me how to get a coil and plug out of a DB9 without pulling the upper intake, you are my hero. Unless you mean the DB9 intake is easier to remove than a Vanquish or a DB7, then yes, I with you on that (damn harness).

 

Hehe..wait my bad..I should correct..you have to remove the intake on all V12's (I can be good but not that good ..just ther newer V12's are faster for me and there are more diagnosic feed back to pin-point 1 more coils compared to the systems on Vanquish and DB7..

 

I am unearthing this topic as I have a misfire on my 04 DB9,as I have access to an AMDS it shows DTC P0312 and P0316 narrowing the probleme to cylinder 12;

I have cleaned all DTC but those codes are back after a short normal drive but disapears when going slow,the car has done 30 000 miles now.

I am thinking of changing coils (2 pins) and plugs on all cylinders as I already have them,before going that route what could be checked , MAF values are equal on each banks and the fuel pressure is ok.

Thanks for your help,I have to do it myself as the nearest main dealer is 3000 sea miles away!

 

I've never seen a P0312 on a DB9, but I've never had a 2004 model, in my area it's just the 2005 onwards for north America..but I don't see it changing anything. Due to the 2 PCM's misfires are from P0301 -P0306 and then labeled for primary or secondary. Nonetheless if u have access to an AMDS, load up the misfire monitor and verify the cyls that are misfiring..does it show the misfire present and do you physically feel the misfire??

 

........OBD 2 scanners...............don't leave home without it! Save yourself lots of money/guessing.........buy one and learn how to use it!

 

Said he had a AMDS...that's Aston Martin's diagnostic scanner

 

Thanks Irish,

my AML DTC guide gives me codes for the "single cylinder misfire" from P0301 to P0312, so from cylinder 1 to 12 (page 2.72).
When I plug the AMDS to check all DTCs I get 312 code and "misfire cylinder 12"
I am not new to diagnistic equipement (JLR IDS,JEEP DRB / STARSCAN)but discovering the AMDS (also have an old AM WDS)the misfire monitor is to be loaded in the datalogger ?
Yes the misfire is easy to feel.
My AMDS is launch mode V1.02 and update 2.12

 

right, I know.......I don't know how that can be.....I thought that system was proprietary?