Originally Posted by
IARLLC
Yes, the file is stock. It will be best if you can hook up to IDS and watch misfires clearly as you go wide open. I have asked HPTuners about adding it before but have not noticed it being added. So I use IDS. It is possible that Forscan might also have live misfire data. I use Forscan for coding Fords but they offer just about all that IDS offers in the way of diag as well.
I run Ford Performance plugs now, gapped .27". I'm sure there are other options but I need cooler plugs for what I do. Also, beware of ebay "Motorcraft" plugs. It is pretty clear that a lot of them are made somewhere else.
I should also mention that it takes them a little while to get past an old misfire. Clearing KAM (Keep Alive Memory) will help it learn fresh characteristics with your new plugs. I'm not absolutely sure of it but it seems that they can expect to see detonation or misfires or whatever in the situation where they used to see it. So after changes it can help to clear memory.
A little hole or tear in a coil boot can cause it to misfire as boost rises. Also very common, if the old plugs were bad and the spark began to take a route down the outside of the plug, that path is often burnt into the rubber boot. In such a case new plugs smooth it out until the cylinder pressure gets high enough to make the route down the outside of the plug an easier path than through the plug and from the electrode to the ground.
I have had quite a few of these come in needing plugs......and boots.