I recently posted about a misfire on cylinder 3 that would not go away... Thank you everyone for the great advice and links to coils...etc.

I found the source of the misfire on #3... the E3 Plug was trashed! The plug was fouled and also obliterated! All replaced with stock replacements, no more E3!

So after fighting the monster for nearly 4hours I got all the plugs completed and the new cops installed. Start it up and the misfire code goes away immediately and the truck idles perfect!

I took it for a test drive and found that the truck falls on its face when I accelerate. It seems to struggle through the gear but then SURGES when it shifts! At one point it actually died when I came to a stop.

The only thing I can think of is a vacuum leak but I am not getting any trouble codes from the computer. It idles perfect in the normal range in Park, but seems to dip in drive and then when you touch the accelerator is coughs, jerks and just feels like its in its death throws! I am also thinking about investigating the passenger side injectors to see if they are seated correctly since I did lift them off the manifold for access.

I'm stuck at work for the remainder of the evening and now all I can do is ponder what the heck is going on.

Any ideas from the gallery?

The truck is a 2003 F150 SuperCrew, 5.4 with 115k on the dial.

Thanks!

Marek

 

Has the throttle body ever been cleaned and how many miles on the fuel filter?

 

Hi Bluejay-

Fuel filter has about 10k on it, have a new one ready to go in.

The Throttle body hasn't been cleaned for a while...

I'm leaning more and more to a vacuum leak somewhere effecting the transmission. The engine seems to be running like a dream but the trans can't figure out whats going on. I am going to dig around tomorrow morning and see if I find anything loose or broken...

 

These transmissions are electronic, they do not use vacuum any more.

 

ok... then I guess I'm back to square one... Crap! It may be misfired like hell before but at least it was drivable!

 

New COP's are not always good COP's or the correct ones. Stick the old ones back in and see what happens. Also when you changed the sparkplugs did you apply antiseize to the threads, to much and the plugs will foul and missfire. Is the air intake tube completely connected at the throttlebody? Is the MAF contaminated or harness reconnected after removing and reinstalling the intake tube? Are the injector and COP wires connected correctly? Just a few things to ponder. Good luck.

 

Another possibility. If you had a plug not burning all the fuel, you could have a cat partially stopped up. I would do the things already mentioned, and if that does not solve it, then have the cats checked.

 

Thanks for the tips!

I had planned to bring back the old COPS and see what happens. There is a good chance I might have over done some of the Anti-Seize... but would that only show up on acceleration and not at idle? I wiped all the Anti_seize into the threads before I screwed the plugs down...didn't leave it all gooped up.

The idles like a dream... all the issues arise the second I apply the gas pedal!

Thanks for the help guys! I appreciate it!

 

In the future, if you use Motorcraft plugs, they do not require antisieze.

 

Good to know!

Thanks!