Hello,

2008 f150 2 wd 4.2L engine v6. had misfire under harder acceleration, CEL came on. #3 cylinder misfire Bought all 6 spark plugs but I only changed the #3 cylinder. Passenger side closest to firewall. I went to autozone and didn't ask for motorcraft., they gave me autolite double something(i can look but..). I wanted to see if that would fix it for a week. It started a little different, should of stopped there, but i drove around and about 15 minutes later it misfired, studdered un hard accel. No CEL, 10 miles I drove. Could it be the autolite? Yes I checked gap. I am going to get motor craft tomorrow. So the question is could it be just the autolite brand? Tested old spark and the ground and tip wasnt getting continuity. Any thoughts? 68K miles, yes I am going to change all 6. Its a work truck and the pens game is on and just cant miss it so put a new spark in, let the guys run it tomrrow, and let them come back and Ill change the rest, they are fairly easy. Easier then glow plugs. Thanks

 

Swap the coil with another cylinder to see if the misfire code moves there or stays at #3.

 

Also make sure there are no vacuum leaks at the manifold or on the PVC/ brake booster hose at the back of the manifold. You should change all plugs and auto lite double platnium are fine.

 

Just posting an update to the issue of #3 cylinder misfire on 2008 Ford f150 4.2 v6 2wd 68K. So I put new spark plugs in oem Motorcraft. the ones that came out of engine were Motorcraft AGSF- 34n (or hn, I forget) they were discontinued so I used Motorcraft AGSF- 34f platinum. After I put new plugs and wires still had a misfire. So I put new coil pack in. fixed. Common issue for the 4.2 v6 engine is if you are getting #3 cylinder misfire it is 8/10 times coil pack bad as well. 3 plugs were broken off in the wires so I took extra caution on getting old spark plugs out. Cranked them a hair and sprayed PB blaster in there and let soak for 5 minutes and turned a little more. None broke in engine side. Very easy fix for anyone who wants to do this them selves and save money. Simply unhook negative battery terminal and wrap in with rubber or something that will not allow it to make contact, unplug spark plug boots, label the wires with tape and mark which spark plug they go to. I simply than took out old plugs and replaced all at once. Coil pack was the easiest coil pack in the world to change. Simple 3 bolts, i believe 8mm. Use de-electrical grease for new wires, Also check the gap on the spark plugs, THEY WERE NOT PRE-GAPED CORRECTLY! Should of been gaped at .054 but they were all .04. The left side of the coil pack is for all the left(passenger) side plugs and right side(in front of vehicle looking at engine) of coil pack is all right side (drivers side). I believe this is correct through my experience. TO MAKE SURE, I would call ford or do a little bit of research to find out exactly. Everything came off pretty smoothly and went back together SMOOTHERRRRR. Started up and ran perfect. Has been 3 days since fixed and truck runs great, accelerates fantastic, and best of all no more misfires of CEL .... Thanks again to all who helped and hopefully this helps someone in need. If you start a thread needing help, PLEASE finish your thread with an updated fix, this helps the next person that is in need, I believe this is what these forums are kinda about? could be wrong on that too. Have a good day YINZ.

 

sounds pretty much what I've been dealing with, hopefully coil pack (singular) majority assume (cop) , went ahead & orderd fuel pump dohicky, bolted it on, no start! DORMAN PRODUCT, Amazon sending another. Had put in Bosch plugs new wires, ran good & started developing odd stumble- miss got code P0303 found a crisp shorted wire ( thinking break interior) . Anyway coil is next as swapping Autolite made no remarkable changes over Bosch

 

Just a note, all right and left designations are from drivers seat , His right is passenger side . So you can see why we use drivers /pass designation instead of r/l . It is a constant battle and can get many people in trouble ,you did good to include both . Add to that the numbering system for cly between manuf also causes headache.