07sl150

New to the site here so first off hello to everyone. I just purchased a 07 f-150 supercab 2wd with the 5.4 triton. Truck has 32 thousand miles. After some drive time with the truck it has thrown a p0420 code if i recall right. I had it read at an avance auto parts and they said that the cats were clogged and needed to be replaced. Upon further inspection both cats have been cut open and hollowed out and welded back shut. So I guess my problem is how do I get the o2 sensors to read correctly again. The truck is running way rich as you can smell almost raw fuel at the pipes and the mileage def reflects it. Thanks in advance as I m a newbie to the truck scene just not on the mechanic aspects.

Mod (Ret.)

Welcome aboard!

Replace the cats. It's illegal to run a vehicle with the cats tampered or removed. It's federal law, so forget those that tell you that the "state does not care".

There are places that can reflash your PCM (powertrain control module), but again, it's illegal.

Install some performance cats, and be done with it. No HP loss, and you're legal, and the codes go away.

07sl150

Ok. My only thing with replacing the cats was I m worried I ll loose the deep loud rumble the truck has running the way it is. These truck s have 2 or 3 total?

speeddemon86

You will no doubt lose some of the sound but it's a proper fix

Mod (Ret.)

Depends on the year. The early trucks ran 4 cats; two on each side coming off of the engine exhaust manifolds. The '07's had 2; one on each side.

Black_05f150

Get magna flow hi flow cats

Mod (Ret.)

The "good" performance cats are less restrictive than the OEM; legal for use as a replacement, and I doubt you'll notice too much of a reduction of "rumble".

07sl150

Ok thanks guys. I appreciate it. I guess I ll have some magnaflow high flow cats put in as it has a magnaflow exhaust on it now. I just looked and it has one one each side plus I guess a resonator behind them in the straight part that has been hollowed also. Will I need to do anything with this or can it just stay?

Mod (Ret.)

Install the two cats. You're good everywhere else.
To clear the code (once the cats are installed), remove the battery negative cable for a couple of minutes, then re-install. Go for a ride, as the PCM will need to relearn the idle characteristics. Don't panic if the idle seems low, this is normal when the battery is disconnected.

Or, maybe the shop that is doing the cat install has a OBD-II reader that can clear the code for you. If this is the case, then removing the negative battery cable will not be required.

07sl150

Ok cool. So the high flows wont throw a cel?