Cmher18

Sorry for this being my first post but trying to help my brother out. He has a 2007 f150 lariat 5.4. Its missing bad idle and drive... Im getting 3 codes cylinders 5/6. And a random misfire... So far i have swap new plugs (broke one) did nothing no change. I swapped coils 1/2 over to 5/6. Nothing still came up miss5/6. I put new injectors in 5/6 nothing.. I checked voltage at the plugs and there reading 12.66.... Now i started to do a compression test but my tester wasn't seated right or i don't have the right adopter. Got to 90 psi and blew out of the whole Either way its got compression. Wat now

Irishjew

Could be a leaky valve. Somewhere on this forum there is a link to a YouTube video of a guy with a special computer program to diagnose it. In that video it explains how a miss can occur even after replacing the plug, coils and fuel injectors. I will look for it and post it after I find it. Good luck with figuring out what's wrong with your bros truck.

Irishjew

Lookup the user ATSTUBE8 on YouTube.

I hope you find your problem.

primalurges

Maybe a blowby in the head gasket between 5 and 6. Any change in the rough idle between when engine is cold versus hot?

Cmher18

It almost seems like it gets worst with temp. But motor temp stays good

Cmher18

Well quick update. Did a leak down and 5/6 had alot... Ended up pulling the heads off and low and behold looks like the cam phasers were on there way out. One tencinor collapsed. Over all the short block is good... Number 5 had a broke valve spring and 6 a bent valve

primalurges

Thanks for the update. Too many threads die a mystery. Glad to hear you were able to resolve your issue.

Cmher18

Should wrap it up tomorrow

Cmher18

Just sucks truck has a 60,230 miles and the passenger side head was warped. And the driver side had the broken stuff got it all back from the machine shop this morning. Im going to guess it jumped time