Engine 05gt Backfire

[05GTDavid]

New to this board. Been researching reasons for backfire on my 05GT. Great info as to what to check. I do not have all the specs about the tune on car I would like to have as I just bought it in Feb. , but it has Ford Racing cai ,BBK short headers&crossover pipe, Pypes axelback muffler deletes. Car ran perfect for about 2 weeks then set a code for Cats. but still ran perfect , about 3 weeks ago I noticed a slight backfire randomly that has gotten worse . It is random that sometimes nothing then it will run like crap for a day then good the next. I saw a lot about the alt. causing a problem for some but just what / how can that be ? I only get the one code for cats and when I clear it it makes no diff. and resets in about 2 weeks. Can bad cats. cause this backfire? I do not know that much about these later ( post carb. ) cars. Thanks for any input you may have to give. Car still runs great otherwise.

 

[05GTDavid]

I see no one has any idea's about what to check or look at on my backfire issue. Sometimes it's so bad I do not want to drive it but it is my only trans. right now. I guess I will have to trust a local shop to try and fix problem , not that I trust too many shops around here to be honest and just shoot straight.

 

[Bullitt95]

Plugged cats could certainly cause a backfire but you might want to rule out possible header leaks.

 

[05GTDavid]

Update; loose plug on #1.

 

[Red Pony]

Same issue for me loose plugs in 1-3, roughly 30,000 since dealer changed. changed all plugs and coil packs, now for the weird part, back fire gone but flashing check engine upon test drive.

 

[Red Pony]

Problem solved, brand new motorcraft plug was bad, no spark whatsoever. Put in an old one with 30,000 on it and car ran fine. American Muscle replaced without issue, swapped for older plug as soon as it was received.