High Flow Cats help
 

ok, so figured out i had blocked cats. they would glow red hot when i drove. pretty bad. so i gutted the 2 front ones, cut the rears off and put on high flows, put the rear o2 within 6" of my rears. is THIS enough to change my tune? truck already has gibson exhaust, headers, tb, electric fans, 4.10 gears, fresh transmission, new upper intake manifold, plugs, etc.

I don't think so but I'll post a note for bill to look at this.

Are you still in NM? Have you gotten your truck registered yet?

The problem with gutting the front two catalytic converters is that you WILL NOT pass emissions because you will get P0420 and P0430 codes due to catalyst efficiency (of which you will have none).

I just talked to Bill about this and his advice was to take your new rear cats, install them in the front locations since the front cats are the ones affected by A/F corrections. You WILL need new tunes to alter the diagnostic strategy for the high-flow cats and also to turn off the rear O2 sensor diagnostic.

yes still in new mexico... well when i get to those codes i'll know thats where i'm supposed to be.... guess i'll try to do some tinkering and see if Gotts Mod will help me out on this one. worth a shot i guess

The Gotts Mod isn't going to fix a cat problem. It DOES seem to improve air intake at high RPMs though.

Try to deal with one issue at a time. Don't go hog wild and change a bunch of things at once. That kind of approach can create strange interactions that cause problems that are hard to diagnose.

- Jack

I think he might be talking about the gotts o2 mod?

OK, :shrug:

- Jack

Gotts has one to many mods, doesn't he?
The Gotts O2 mod with pics - F150online Forums