bubbabud

Removed cat's, O2 sensor code, no power, duh.

rcairbear

No O2 sensors- really? You might have answered your own question. Pretty sure the PCM needs that information.

supersnake04

It's still got the downpipe o2 sensors where they're supposed to be. but the rear ones just aren't hooked up to the exhaust, I've got them plugged in, but they're Just sitting on the frame. I need to find a set of o2 deletes.

Jbrew

Right! That's why it's way down on on power. You can't remove the cats and run it that way without being WAY down on power. So far down on power that truck won't be able to get out it's own way lol. UNLESS....you modify the tune. The only thing stopping these engines from running cat-less is the tune. So, you have to adjust the AF's to mix properly without cats. They are far outside of margins which will eventually burn that engine up if you don't. Removing all of the cats is probably one of the most foolish things you can do UNLESS,- you know everything about what your doing and cover all the bases before hand.

supersnake04

oh, that explains why it runs like s***. Thanks. So if I get it tuned, can it be programmed to ignore the lack of input from the rear o2s? Or will it still need o2 deletes?

Jbrew

Yes and yes. Your mileage MAY suffer without the rear O2's. They are more than just cat checkers, but that's about it. Usually mileage isn't affected with the built engines. The factory builds tend to get a little less. Now if you reinstall just the smaller upstream cats, you won't need a tune and you'll get your power back. Your still within parameter margins running just one of the smaller cats on each side. That's what most do since it is the cheap way and the vehicle is much louder. The upstream converter although smaller is more restrictive than the larger downstream. This way you can run all of your O2's and won't get a DTC IF your connections are tight...it can't leak very much in the Y, -or you'll get a CEL with this set up.

supersnake04

Whoever mentioned lack of maintenance was right on the money, lol. I just changed the air filter (which was almost black) and the fuel filter (which was so clogged up that it barely had a trickle with the pump on, and was full of black sludge and sediment) both where factory parts. I had also changed the factory spark plugs a few weeks ago. Truck will haul *** now. Lol I was seriously surprise how much power it gained from simple maintenance that had been neglected for the last 14 years.

comanchepilot

It's a truck. It's designed to haul stuff - it was never designed to be a NASCAR Truck racer. The vehicle is heavy.

I have a Cayenne V8 with 400hp - sure - that gets up and moves- weighs about the same - but its got 180 more hp. Even if you got the 5.4L V8, it was designed and optimized for towing - very torquey motors. That's great when hauling stuff to the dump - or towing a trailer - crappy if you're looking off the line power.

Why buy a 97-04 F-150 if you want spritely off the line?

Vortex

jbrew for president!!!