This all started about 1 year ago running really bad took it to ford said a coil was bad replaced it ran great now it only has 75K miles on it ok. This year started to run like crap again took it to ford said 2 coils were bad replaced them ran ok. Now just 2 months ago it ran like crap very hard misfire so I went out bought a snapon solus pro scanner was tired of taking it to ford. Well I drove it around hooked up my snapon dealer told me this would tell me what cylinder was not firing ok so I drive and tells me #9 was a very non contributing cylinder had 2 extra coils put one on still ran like crap. Thinking what is going on called snapon told you need to use mode 6 ok did that no problems or codes would come up what so ever. So I thought ok maybe its a plug it has 78K on by now so took it to ford had all the plugs replaced started to drive it home bucking again so now I am really mad, I opened the hood and when they replaced the plugs took coil off #9 and put it on 10 so got my other coil put it back on number 9. Figured hey got the problem fixed but the scanner was still telling me it was #9 called snapon again you need to do the cylinder contibution test which I was doing still tells me #9. Running like crap so I cant take it anymore take it to ford they tell me its #3 repalced the coil one of the remaining 5 runs ok not great but not like it was so here I am 3K scanner which wont tell me jack on this ford engine. Went out and replaced the remaing 5 coils it runs and gets better mileage so its a good thing. But my Question is why didnt the scanner tell me there was a misfire on one cylinder that was not really having a problem and the one that was passed. Any one else have this problem with fords as to not being able to tell what coil is not firing correctly????

 

My truck is a bear like that too. I finally just replaced all the coils, boots and plugs. Been fine since.

99 F-350 Lariat 4x4 V10 CC LB

 

yea im not a fan or replacing just 1 coil..

better to do them all at the same time, and be certain of the lifespan going forward..