I am hoping someone can give the authoritative answer to the following Vantage V8 misfire learn question for 2010 onwards cars. There is a lot of somewhat confusing information about this topic, possibly because of the early models being so different from the later, the Sportshift i vs ii and manual cars etc.

It appears from what I have found that on early cars a misfire learn was required whenever a battery disconnect occurred or some other major ECU reprogramming was undertaken. Further it appears that particularly on manual cars, the misfire learn could happen on its own after several hundred miles of driving. However, it appears that on earlier Sportshift boxes the learning only occurred with the AC off and the vehicle in D mode. Given how truly awful my Sportshift ii D mode is, I doubt anyone even drove any distance in that mode and so only an active 'manual forced learn' would ever work. Indeed, one DB9 owner reports that he may have driven thousands of miles without a misfire learn being completed and this had odd side effects. This, incredibly, included the ECU not registering genuine misfires as P fault codes since the learn had not been completed. After the learn he could read the P fault code for the offending cylinder.

Things seem different from 2010. It is mentioned in some postings that for these later cars, the misfire learn is retained for all time after the initial one and that only AM dealers can reset so that a re-learn can be undertaken.

Is this correct? If so, under what circumstances would a conscientious 2015 Vantage V8 owner who lives 6 hours from the nearest AM dealer want the misfire learn reset? In other words, for these later cars is it a real world issue?

Regards

Philip

 

The misfires wont learn in "D". IIFC you need to be in 3rd gear, no AC, and get the engine RPM up to ~4500 and let it coast (in 3rd gear) down to ~1500 RPM. Try that 3-4 times in a row and it should stick, you wont be able to tell without connecting an AMDS if they actually took or not though.

 

Thanks for the reply, but it reinforces my observation that there is a lot of confusion about this process. The earlier DB 9 official service bulletin specifically states that for automated transmissions that the automatic gear section must be used, not the paddle option. Of course this is a different car from a different time, but others recommend D option on the Vantage and it apparently has worked for some (car age and success percentage rate unclear). I do not know of a later service bulletin, but that may be my ignorance. Your are the first to ever mention rpm rather than speed and doing the whole thing in 3rd gear.

It is also still unclear if the later Vantage models are looking to recalibrate if they believe they have a valid previous set. In other words, after wearing a red not green T shirt, one black and one white sock, driving in 3rd, accelerating slowly then smartly, patting your stomach and coasting on a pool table smooth road with no braking and no AC, that if the engine management system shows a learned status, it is a new learned status, or just the previous learned status and the driver was totally wasting their time all along A) because a new set was not needed or B) because even if it was needed, only an AM dealer can get the later cars into a mode where they are receptive to relearning.

Philip