My truck BEFORE i cut the cats out got around 15.5 mpg around town and AFTER i cut them out I'm getting around 17.5 mpg around town. And may i remind you that i still haven't done anything to my computer such as a tune or chip. Is this the norm? I was thinking the back pressure had something to do with it. But every one i talk to says it should go down Has this ever happened to any of ya'll? Or do i just have a really weird truck? Let me know somthin' guy's and gal's. ThAnKs!

 

UM, who says it should go down? Ive removed the cats from EVERY VEhicle Ive ever owned that had them.. and performance and mileage ALWAYS go up.. The only time I can see mileage going down, would be on a turbo'd motor, sometimes if you open the exhaust up, and dont let it breathe more air in.. i have seen negative results on mileage.. But with a gasser, opening everything up, like u have done, will increase mileage, and torq.. as well as HP..

 

im very surprised the truck didnt stay in open loop........how many miles does it have???? as it gets older i think your going to see a slight decline in mileage......

 

X2 Do you have O2's after the cats? It is still possible that your mileage went up. Maybe your cats were getting clogged and this solved that. You might have seen similar results if you had just replaced your cats with some new hi flowing cats. Glad to hear you found some mileage though.

 

CATS are worthless. glad it went up, still planning on getting a tuner or a tune for it?

 

Lucas, Ive had SEVERAL chevy gassers, matter of fact I still own one, 92 Z71 with crate 350 TBI.. (getting a transplant soon tho.. ) and I've run 3 or 4 different types of programmers on them for performance and mileage. Ive had alot of luck with Hypertechs on the Chevy Gassers. Also, if you want a lil more mileage, you might check out Throttle body spacers. Ive run Helix Power Tower on my last 3 SBC Trucks, and I love them..

 

i felt more power with my TB spacers than headers.

 

yes i'm still planning on getting a custom tune for it from nelson performance after i save up some money it's close to 400 smakers to pay for the new computer. it has two o2 sensors behind both the cats, unplugged though. millage is 250,000. When my dad bought the truck new in '99 it got right at 19mpg.

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i'll look in to the tb spacer, but i have to make a custom bracket for the cables the at go to the pedal and tranny. And i'm not planning on putting headers on the account of the back pressure issue. funny thing is my dad wasn't too trilled about it b/c he didn't want the service engine soon light to come on and my mileage to go down

 

here is a quick simple thing to try to clear the check engine light that is more than likely on due to the rear O2's being unplugged. go and buy 4 of the big spark plug non-foulers. they are the same thread as the o2 sensor bung. it might be best to take one out and take it with you to make sure you get the right ones. screw 2 of them together, put it in the exhaust pipe in the o2 bung that is already there, then screw in the o2 to the new adapter you made. plug o2 in and the light should go out. do this on both rear sensors hince the 4 non-foulers you need to buy. if it doesn't work you will only be out a few bucks but i know alot of Jeep guys that do this and it works for them.

 

that sounds like a great idea benjamin, but there is only one problem with it, I cut past the O2 bung to get the pipes to fit.