Hi

I have a 2005 5.4 4wd while towing a small boat(light) uphill overdrive off brought the check engine light on and makes dieseling noise and missing and big loss of power. oil was full and just changed with mobil 1 and pressure stayed good and going level or down hill runs fine but every hill(turned around) same thing and once engine light blinked for a minute. motor is 150k highway miles plugs changed 120k, scan tool only shows po303 and po307(across from each other?) . back at home start fine idles well and revs good. should i start with injectors on 3 and 7 (none ever changed). or do you think this is a timing issue or spark

thanks for help

 

05 does have that injector extended warranty but your past it. goes to 130k I think. Hard to say. What plugs did you use? How about your coils? Stock? I would normally think coils first.. Swap them with 1 & 6 and see if the miss(both) moves. Under stress they seem to fail..

 

The plugs were done at ford no coils have been changed. drove downtown today 6 miles each way cleared codes ran fine down to town put some octane boost incase the cheap gas was causing the pinging which is timed to revs on the way back once i heard a ping for a second or two threw no codes let off on gas and finished the trip okay. no missing and no other noise

 

you might pick up a set of them cheap e-bay coils global and uneek supply are selling them for about $110 a set. Thats where I'd start. Save the known good ones in case of a failure.

 

Thanks, this weekend i will swap coils, just out of curiosity what might cause a seqencial misfire in the firing order it goes 1,3,7 and the only codes thrown on near stalling were the p0303, and the po307

 

Well, theres the cam on that side.. Cam phasers maybe.. Might be your cam chain tensioners are shot.. thats kind of a big deal. a couple grand to repair it at the dealer..

 

thanks jethat for help so far
before i change phaser stuff....., what sensors can be unplugged to keep from engaging phasers for test purposes .this truck never had an issue until i had dealer change plugs, then 400 miles later miss fires bad took it back and they told me it blew head gasket, they fix it, now this po303 and 307 that wont go away, it only happens when hot and going long uphill or uphill on interstate. i have replaced 7 with new coil and its connector and swap around and greased all other other coils(they were all dry think dealer would have greased them) and changed coil connector on 3 as well (ford tech told me they failed alot) ran great for 3 days then uphill knocking and misfire comes back and again po307 !@#$%%^