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Guys,
I posted a thread 4 weeks ago about an engine miss but no CEL. The problem was very intermittent and would quickly clear itslef up. My plan was to leave it alone until the truck told me what was wrong with it which it finally did.
So, like I said I finally got a code: P0303 which is a miss on cylinder 3 per Autozone. Anyway, the problem was intermittent and never caused the truck to stall. In fact, it would clear itself up before setting the code but on Tuesday (very cold day) it finally flashed the code. The Autozone tech seems to think its a plug because it's intermittent. He said that if the coil pack goes, it goes completely out. However, I think there are only two packs on this truck, each one controlling 4 cylinders...if the pack goes out, won't it affect the other cylinders? I'm trying to figure out the best (cheapest) course of action. Should I start with the pack ($48) or start changing plugs/wires? If you recommend replacing stuff, what brand should I go with? Lastly, when I'm done, should I reset the CEL or let the computer recognize the fix and reset? Thanks for the assist.
if you dont know how long its been since the plugs and wires have been changed it wont hurt to get it out of the way, mite get a 1-2mpg better fuel while your at it even shouldnt be that costly especially if your doing it yourself. if that doesnt clear it up try doing like mentioned above and swapping the coil pack to the other side to see if it changes your code, if it does you know were the problem is
1. Swap coil packs and see if the misfire moves to the other bank.
2. Reset the PCM. Simply remove the 3A or 5A minifuse in that little box back there in the driver's side corner under the hood spring. Leave the fuse out while you're swapping coils, reinstall when done.
Be prepared to replace the plugs and wires. Suggest only Motorcraft plugs unless you know exactly what you are doing. Can't go wrong with Motorcraft wires either, but they are not as crucial as the plugs.