Possible misses on #5

[lil_dq]

Ok guys my truck is stumbling at idle not too bad but enough for me to notice. If I take her out on the interstate it will throw itself into safe mode and pop a cylinder 5 missfire code. I can clear it out with my scanner and limp her home. but if I stay around town and don't put a load on the truck real bad it seems to be fine. It is an 02 F150 5.4 that I recently installed a supercharger on.

Here is what I have done...

Changed coil on number 5---> no change
Switched plug and coil to number 6 location and a miss still shows on number 5.

I am going to pull compression and compare it to the others but I was curious if there were other factors that I should look into. I can get the valve covers off pretty easily and that is probably my tomorrow project but do I need to look for anything in particular.

Would a valve spring being weak have the same effect?

 

[d-kuzmen]

When you have the cover off make sure the rockers are still in there correct location, switch fuel injectors to see if the skip moves. Check compression.