omarrakeen

iTrader: (2)

tune. i have the seem thing along with O2 codes. this is one a zero leaking exhaust. i can literally smell the unburnt fuel! i noticed it the past week ill wait for the cam to tune

MR WESST 02

eventually i got a code for a bad 02 on b1s1. replaced it with a denzo. now the gas mileage seems back to normal. after i installed the 02 i put about 300 miles on it and no codes came back. then tonight i went through 3 gears and i got p0410 (secondary air something. air pump.) and slow response for the new 02 b1s1. these codes are starting to **** me off..

ponyeater01LS1

hey MCFLY YOU NEED A TUNE YOU BLOCK HEAD thats the problem you need a tune anything other than stock **** on a car is gonna mess with stuff go get a tune and it will correct your mileage maybe even get more out of it, after you GET A TUNE!

1madss

iTrader: (10)

So adding LTs without getting it tuned causes a %50 reduction in mileage.......

No way. It's something mechanical. I ran my LTs for years and never had it tuned (many years before even LS1 Edit was out). Hell, I ran my H/C combo for 5 years with nothing but HPP# tuning and still got 25mpg highway with 4.11 gears.

Will a tune help. Yes! But this is not the major culprit here.

RevGTO

iTrader: (12)

If you ditched your air pump, then you'll have that code till you get it tuned out. And welcome to the fun world of LT's and O2 sensors. You'll probably want to tune most of your O2 codes to not report because they rarely work to what the PCM expects with LT's.

Full-Force

iTrader: (11)

Bottom line for the record since this is a place people come to get info. Headers do not make car use more gas. In fact I would say just the opposite. They are much more efficient so it should improve.

With the exception of WOT tune being off and using more gas your mileage should not go down. At part throttle (closed loop) the PCM will maintain 14.7:1 assuming o2's are operating right.

MR WESST 02

yeah its all figured out now. it was just a bad 02 sensor. getting a tune within the next couple weeks.

heres what i did for numbers the other day.
https://ls1tech.com/forums/dynamomet...ud-videos.html