spark plugs and wire problems

[brandon vaughan]

Need help please, I just put new plugs and wires on my 04 4.0 st, I put the autolite double platinum plugs gapped to 1.39mm and the autolite professional series 8mm wires on. Well i ended up cracking the ceramic on 2 of the plugs when i installed them and didn't notice it when i went to drive it the truck bogged down when under a load about 3000-4000 rpms i came home pulled the plugs and bought 2 new ones and put them in, on the 2 test drive the same thing happened and my check engine light flashed a few times only when i got on the gas but wont give me a code on my scanner? please help

 

[EddieS'04]

Make sure the plug wires are securly snaped into postion. If even one of them is not fully snaped in, it can cause intermentent misfires, that you may not detect...

 

[Todd Z]

The gap on the plugs is .054 I don't know what the MM equivalent is, But I think that may be the first issue...



Second, Make sure the firing order is correct and also check everywhere you worked that you did not knock off or break a vacuum line...



Todd Z

 

[Gavin Allan]

I had a bad plug last time I changed mine. Looked fine, but misfired. Replaced plug with identical new one and it ran fine.

 

[Tom Schindler]

.054" = 1.3716mm



1.4mm is about .055" gap.



Your gap is fine.



Are you sure you did not crack the new plugs. Another thought, I do not care for any other brand of plugs than Motorcraft. People claim that Autolite plugs are the same as Motorcraft, but I am not willing to take that chance.



Check you firing order. You coil should have the plug numbers on it and make sure they are going to the proper plug.



If need be, you will need to remove each plug and make sure they are intact and not broken in any way.





Tom

 

[brandon vaughan]

Thanks for the replys i ended up finding one with a small hair line crack, replaced it and the truck runs great. Thanks again

Brandon