07 #8 miss and others

[hvacmech]

I have a 07 EL EB 4x4 with 136000 miles I just picked up last week. It had a slight miss under heavy throttle at interstate speeds. It still had the factory plugs so I changed them (3 came out 5 broke and had to be extracted). So now it has a dead miss on #8 and the cylinder contribution test shows some misses on cylinder's 1,5,6,7. On #8 I replaced coil, another plug, and injector but still have the miss. What have I done wrong.

 

[stamp11127]

From what I've read on other posts these engines are finicky as to the brand of plug used. Sounds like bs but we are now in the age of razzle dazzle electronics and just being out of spec a little can throw a code.

What brand of plug, what is the plug gap and what brand of coil did you install?

If you didn't replace any of the springs/boots that could be your problem. Those have a life span and probably should be changed out of habit with the plugs.

 

[f150dave2002]

The replacement motor craft SP 515 Plugs can not be gaped. Check for cracks in the coil pack boots. Replace boots if they are cracked. Don't forget dialectic grease...

 

[hvacmech]

I got it fixed this weekend. I did replace the boots and springs with the plugs. But the coil I used was a Autozone duralast. I picked up a Motorcraft coil and that fixed #8, but still had random misses on other cylinders. I found a older TSB for 05 and 06 years that said to use SP514 plugs in engines with spark nock or random misfires(one heat range colder). Found a set at the local dealer and all is good now. Thank you guys for the help.