Severe misfiring on 5.4L

[1955moose]

Yep, he's not paying attention to past posts! Misfires kill cats. At this point you need to figure out what's causing misfire, then do a full exaust back pressure test, sounds like you've got ow, and meow, as in misses, and Kitty's not Happy! Kitty's are expensive!

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[gflat65]

Someone mentioned early on that it if nothing else pans out to check the cats. I will check O2 sensors and pressure at the cat (and probably start with full exhaust pressure test).

What issues are there with the universal clamp in cats, if one is bad?

Are the four different cats on the 2002 5.4L different from one another in function?

I've had it two years, and have only put 7-8000 miles on it. It's probably been driven 60-80 miles since the issue started. I use it more for utility that as a daily driver.

 

[1997SCEBFEX]

I think inferred here, check your cables too.
++ on ohming out COPs.

battery cables for specificity. might be on to something else by now.

 

[Joseph3]

I just went through a severe misfire problem out on the road that got me stuck in Wenatchee WA for three days awaiting service. Turned out to be mainly a coil pack failure on cylinder 2. Replaced the single coil and all of the spark plugs and my rough idling/misfiring/SES light flashing all went away. Wenatchee was nice.

 

[ManUpOrShutUp]

http://easyautodiagnostics.com/ford/4.6L-5.4L/how-to-test-the-cop-coils-1