mustang6640

I have a 2006 f-150 with a 5.4 3v 4x4. A few weeks ago it started running horrible. At idle it sounds fine but when you start accelerating it had no power and it pops and back fires. I just replaced all the spark plugs. Its been throwing codes for #5 and #7 cyclinders missing firing. I also had a code for the catalytic converter but i did clear it and it went away. Ive been doing some research and narrowed it down to the cam phaser being bad or the catalytic converter being clogged. Most people have told me if the cam phasers went bad it would sound like a diesel at idle as far as clattering. Mine does not. Thats why im leaning towards the cats. Please let me know if anyone else knows what might be the problem. Thanks.

R.S.LOGAN

Checked the plug wires , firing order / timing ?

Lincoln1

This may sound silly but it happened to mine...try if you can to dissconnect the exhaust before the cats, see if it still runs rough...my cats where plugged, ie melted, a injector was failing and raw gas was leaking into cat..hope your spark plugs are in good shape..

mustang6640

I had the cat. pressure checked and the driver side is totally plugged. So i had it replaced and it runs 10 times better. Thanks.

R.S.LOGAN

Good to hear you got car fixed , thanks for update .

Bluegrass

Wow!.
First there are no plug wires.
Next there is no timing to set.
Next having two cylinders dead will pass raw gas to the cats in that bank whre it ignites overheats and melts them if driven very long.
Clearing the cat codes is only temperory until the PCM looks at them again and resets the code.
Have you checked on the cost of OEM cats and OX sensors and labor lately?
Ya just can't fool on these engines without knowing what your doing.
Good luck.