i have a 2006 ford f 150 with a 5.4 Triton 3v engine and every time i floor it and the engine reaches 3000 rpms the truck backfires and looses power. sometimes it wont pass 3000 rpm it just stays there and backfire and have no power. sometimes the check engine light flashes......i took the coils off and looked at them and they all looked pretty clean. also the truck idles rough and sometimes when it cruising at low rpms, and i give it a little gas the truck will randomly misfire and shake hard. also the engine sounds like a diesel engine........ does any one know what might be wrong

 

How many miles are on it? Take it in to an auto parts store that will read any stored codes. That will give you a starting point. It could be several things. VCT solonoids plugs, or cop's. I don't think you can diagnose a bad cop by just looking at it. You could have carbon trails down the side of a plug or plugs is another thing.

 

Mine was doing the same thing and it was bad plugs. Changed them to champions and no more backfiring or power loss at high rpms, but still has the rough idle. Also fried my cats because of all the unburnt fuel being dumped into them.

 

definitely have your cats checked, I had been fighting mine running rough and backfiring through the intake. New plugs, cops, filters, and yesterday found out that drivers side was completley clogged. Just had him put straight pipe in its place and it runs awesome!

 

thanks ill try all of those suggestions

 

Hi there. I would first like to say this site is awesome!! I have already fixed a few of the little issues with my 07 Screw, including this one. I was getting the same miss fire/ back fire under wot. Dealer said it was the cats. I then went on this site and read that the plugs are usually the problem. So last weekend I decided to tackle the job myself. (save a bunch of money) By following the reports from other users I removed all 8 without one breaking. talk about stressful. Took the truck back on the road dropped the hammer and the miss fire is gone!! I think changing the plugs is the cheapest way to solve this problem. After comparing the old plugs to the new ones there was about a .030" difference in the plug gap, and thats only after 70000 km. I replaced the stock plugs with motorcraft's sp-515 which is supposed to be the answer to the plug breaking problem. Good luck!!

 

Myfav8.... any updates? fixed?

 

I have a 2005 F-150 that was back firing under load and would loose all power, the exact same symptoms as Myfav8. I replaced the exhaust from the engine all the way to the back and it seemed to help a little. After reading this forum i decided to replace the spark plugs again which i had the ford dealer replace due to the breaking problem. The plugs only had 35k on them so i was skeptical about that being the problem and i put champion double platinum plugs in it and now it runs like a whole new truck. I hope this helps anyone with the same issues.

 

Replaced my plugs to solve the "bucking" problem. Found out that Champion has an updated plug from the old one. Apparently a 1 piece plug to alleviate breaking them off.