Hello, I purchased a 2008 5.4l superduty with 84k a month ago and it has been at ford where I bought it, for a total of three of those weeks for a random missfire. I used my sct to scan for codes the first time, where I located cylinder 7 was the problem ford replaced cop and plug and the truck ran slightly better. The second time it was at ford I couldn't get a mil to stick so they tried for two weeks and told me it had no problems and ran fine, I got rude and all of a sudden the next day they found the problem, cylinder 4 coil and plug change and I'm back where I started. I'm giving up on using ford because they are giving me the run around so any advice would be appreciated. The truck missfires under a load or at wot on the low end and around 45 mph. I cant get a mil to stick, however, I pulled a PO300 random misfire code. Where do I begin? Thanks in advance!!!

 

Change all the plugs. At 84k they are overdue.

 

Well, I changed six of the 8 the other two ford will have to retrieve they broke off in the head. So when I get my truck back in a month I will let you know if it was the cause. ..

 

A month??? A Lisle tool is 60 bucks, you can extract the broken ones yourself.

 

I just you tubed that tool for the 3v pretty neat! Thanks for the suggestion! A month was an exaggeration, the truck came with a 1000 mile bumper to bumper warranty ever since the test drive it had the missfire, so I took it in for the work but ford said they couldn't get it to missfire the whole time they had it, they put 265 miles on it and didn't even return it to me with any gas in it ( I dropped it off with 30+ gallons in it). So I complained to the manager that the fuel gauge is at 9 miles till empty and I had a full tank and they drove it to the gas station and filled it up to 1/4 of a tank, I went back inside and asked them if its normal to sell a return customer who just bought a brand new f150 a year ago a broken truck then put a ton of miles on it and not even fill his tank, not to mention fix the missfire? So needless to say its not at that dealer now I found a polite one and when I buy a new truck in 2016 the new dealer will have all of my business.