hi i am new to forum i have an 06 fx4 the cel came on and i pulled code it says #8 misfire detected engine runs relativly well but is a little harder to start sometimes starts well when cold but i have to hit key two or three times before it will catch i changed that cylinders cop and plu one week later same code appears any suggestions injector maybe any help will be appreciated thanks in advance

 

i would lean towards the injector yes. only because you said you replaced the COP and Plug.

 

First off welcome to the forums! I hope you find it a useful source and enjoy what it can offer.

Now to your problem we need some more information. Since you have gone ahead and changed the COP I am going to assume the plugs have been changed. But I am curious as to when and what kind of plugs where used? Plus I wanted to know how many miles are on the truck and what else has been done recently?

 

to coskid, he truck has 34,790 miles it just recently started acting up. truck is bone stock, fuel filter and air filter were changed 3000 miles ago in late summer i use 5-30 semi synthetic motorcraft oil and filters and do my own maintenaince.

 

to coskid, i only replaced the one sparkplug in #8 as i was pressed for time when i changed the coil, thanks.

 

OK I was figuring it had more miles on being an 06 so my first thought is out the window. I agree with shawn and lean towards the injector at this point.

 

just out of curiosity though, are you experiencing problems as such.......

when you are going down the road and the overdrive kicks in ( approx 60 mph ), and you floor it, does it misfire, kick and jerk, and sound like it is backfiring through the intake?

 

to coskid sparkplugs going back in are motorcraft, just like came out. also spark plug did not come out that hard. to shawn n, only other symptoms are slight miss at idle and at tip in after that miss goes away i will be trying a can of seafoam first i always use mobil or shell gas from the same two stations thanks for replys

 

ok then. i was just trying to compare what symtoms you have with what i believe is going on with mine as i made a thread topic as well. But i have not yet replaced the fuel filter/plugs/COP yet on my misfire on cyl 5. but i am also not throwing a code. mine just misfires under a heavy acceleration at cruising speeds.

 

to shawn n i try not to drive it that way! i do tow a 7000 # travel trailer from time to time and it never skipas a beat. just starts funky and sometimes misses at idle and tip in, otherwise yoy would never know there was a problem if stupid cel light didnt come on, theres a lot to go wrong with thesee things and most times it works pretty good. i like my truck!

 

update, a little late. cel has not come on since I ran two cans of seafoam and a bottle of stp through the fuel tank, also switched from mobil to shell gasoline. starting issues are gone also.

 

I know mine does this. My local mechanic can't figure out the problem..... Im thinking i need to go somewhere else if i cant fix it myself.

 

https://www.ford-trucks.com/forums/1...t-misfire.html Maybe it is yours lucky day that I come to another G of F150 for a day. If it is #8 there is good chance problem is like in mine truck.