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2006 f150, 5.4l.

Basically it runs good 90% of the time. Periodically it will act like it misfires, usually between 45-70mph. Happens only a couple times a day. Hooked up a scanner and it showed the data stream as I was driving. Everything looked good, no codes.

Thinking at first a gas issue so I threw on another fuel filter and heet in the tank in case of water. No difference. Replaced the fuel module cuz it looked in bad shape. No difference.
Thought about new coils but before I just throw parts at it I thought I would ask and see if anybody else might have had this issue.

Forgot to add it only happens on slight acceleration. I can floor it and it runs as advertised. I thought of TPS may have a dead spot, crap clogging the sock on the fuel pump but it should happen at any speed. Maybe a tray issue? Lock up acting up?

I'm just stumped.

I've not worked on the new stuff but what about cap and rotor and wires?

I had a similar issue with a 02 F150, 4.6 . Have you ran a scan tool on the coil packs . I had one of those go out and caused the same issues you're talking about.

I had similar problems but only when it had been running an hour or longer. Turned out something as simple as a couple of plug wires building up heat and resistance.

The scanner I was using is supposed to pick up each cylinder through its cycle. A friend used it and that's how he picked up his bad coil. It's pointing to a coil but I can't pick it up.

New coils are cheap but I hate just throwing parts and hoping. Think I'm gonna have to do it.

FYI, the triton engines don't have a cap and rotor and wires. That would be to easy. Each cylinder has its own coil pack.

Rubber boots need replacing, they get hard and crack and arc causing your miss. Won't set a code neither unless you really make it miss hard.

Watch the engine run in the dark. If it's arcing, often you can see the sparks.

I suspected as much, but I've never even popped the hood on one. Good luck tracking it down.

My 07 F-150 was doing that, and I replaced the plugs and coil packs and it has run great ever since. It had 140,000 miles on it when it started acting up.

How many miles on it and how old are the plugs? In the old days we'd call that a "lean misfire". It would happen when plugs were worn and it takes a bunch of voltage to fire with a lean mixture. It takes a LOT more voltage to make a worn plug fire compared to a new one.

Sometimes the ignition just couldn't put enough power out to fire the plugs and an engine would miss.

I suppose the coils being weak would have similar symptoms.

Notorious for coil packs

Coil packs for me also on my 02 5.4L. Replaced the Coil packs. No more issues. I've got 250K+ miles on mine.

Roughly 145k on engine. 60k on plugs. Tonight I finally got a code for a misfire on #7. Good timing since my coils I ordered came yesterday. Replaced the coils tonight and I'll see how it runs tomorrow. Atleast I can eliminate the coil if still has a mis.

Do a little research before you change the plugs. A friend, retired mechanic, spent over 1k when he had trouble with the galded plugs in his truck.

Replaced the coil packs. Runs as advertised.