slapped in a new Cat, 2 new NGK o2's and new ngk plugs and mpg (mostly hiway) is now up to 14.0 mpg... havent had that in months. still have a leaky plenum gasket though. I'm hoping to fix that in the next month or so... maybe 16 mpg??? who knows but it sure would be nice!!!

 

****, I'm thrilled to get 9!!

LOL!
Those 35's and the lift really sent my fuel economy down the crapper!!

 

yeah, I was supprised, I was thinking there was one more thing killing my mpg... the plenum leak. I'm sure it's killing some power too. What kind of o2's do you have? It has been recommended to get the NGK's from ngk.com, for my truck, they were $60 bux a piece. Also, some of the other mods I did really helped out the mpg... the best I ever got consistently was 14.8 mpg, and that was just before my plenum started leaking, (my guess anyway, cause the power dropped off a bit).

 

Damn Steve, I get avg. 15 hwy and city with NO mods & all orig Cat, wires, etc. Non- synthetic fluids too.

Maybe you should ease off the gas pedal a bit.....

 

what does getting a new o2 sensor do? where the hell is it located anyway? heh

 

I used to get 15 mpg on average. It's between 11 and 12 right now. I think the 285 tires hurt the most, but I've gotta check the plenum too just in case. Seemed to happen pretty much overnight.

 

ah yeah! Right foot is really heavy, but the 14mpg came with a bungy cord attached to the right toes and the steering wheel [sm=sleeping.gif] I do have a leaky plenum gasket which will hurt the mpg. It'll also kill the o2's over time so now that I have the new o2's in there I need to get my *** in gear and fix it asap...

the other thing to that I should mention is the gas and the additives have a lot to do with mpg performance... last summer when i went to Yellowstone I averaged 14 mpg out to the park, then 15.8 on the way back for 2 tank fulls... I filled up in Wyoming and Utah when I got the 15.8. as soon as I filled up in Nevada and CA, mpg dropped... yeah, california gas sucks!!

 

I have the 285's (soon to be 295's) and the 4.11's front & rear... had that setup when I went to Yellowstone btw. Check your plenum gasket... and get the NGK o2's...

 

Depends on what year truck you have, mine has 4 o2's, 2 primary's on each exhaust bank and 2 secondaries for monitoring cat effeciency... on my truck I lucked out, supposedly there is a s/w bug that does not report the o2 failures and since my primary o2's are empty, no CE light... I did however put on the carsound hi flow cat for the 3rd cat. It would be interesting to see how my truck would do on the smog test...

 

You are exactly right. I just noticed your signature. Your state gov't works hard to provide you with that quality gas. The county I live in in Va does not have any emissions inspections (yet) or gas additives that I know of. All we have is a state inspection yearly where they check the exhaust (usually by putting a hand on the tailpipe) to see if it is leaking.