496chevy

alright, im no tuning jesus, i dont fully understand hptuners. i have done some reasearch and find the process of going through one one button at a time and searching how to /where to find the value for my truck. i.e. lean rich voltages for the o2's, just about everything besides the trans shift points, and pressure. that doesnt do anything for my hwy mpg.
heres what i got.

1987 silverado (short bed) 2004 5.3, 4l60e (2000 pcm) w/3.08 gears
ive been driving around and havnt ever ever hit 20 mpg on the highway yet!!?! now i know trucks in general are aerodynamic bricks, but i should be hit 20 on strait highway right? ive done a mpg post on this site and got the concensis that i could do better.

what would you guys (thats tuned for yourselves) recommend me looking into and modifying for better mpg. if you have any tutorials handy, i will add it to my collection. i do NOT have a wideband. im sure i could snag a botch 4.2 wideband from a bmw (from work) and run it through the a/c pressure signal wire, but im not 100% sure how to set up a pid for that or if i need a signal converter.
i travel 20 miles strait highway to work, 30 miles strait highway to school, seriously another 19 miles strait highway to home... so if i can start tapping into the 20mpg+ i would be very gracious.

99LoweredSierra

iTrader: (7)

I get around 18 on the gas some!! Thread needs to be moved out of dodge thread though!!

shakinlm7

iTrader: (5)

18 is the best I've EVER seen out of mine too

trever1t

iTrader: (14)

move to the GM tuning section

496chevy

sorry about that 99lowered, and thanks trever1t...

trever1t

iTrader: (14)

no problem. I find I get a tremendous rise in mpg slowing down, keeping the rpms at 2000 rpm or lower. Sucks to let cars fly by but nice to save fuel on the long road.

RandomHero

iTrader: (24)

I get around 21-22 with my extended cab truck 29" tires and 3.42s driving around 80 mpg. If I keep my rpms around 2200 or higher my gas mileage plummets dramatically.

Wide Open

You didn't mention if your truck is 2WD or 4WD. It makes a difference. You should be able to hit 20's with the 3.08 gears. What is your tire size?

nonnieselman

iTrader: (10)

i would think that 3.42s would give you a lil better mileage compared to the 3.08s... whats your rpms at 70? and whats your tire size? You dont want to be too low of a RPM while cruising or its goin to bog some and put a load on the engine..

I can get 23.5 out of my truck.. but it has to be all highway driving.. stop and go driving my mileage drops to 16-17 real fast..

i have 3.42s and 29" tires... 68mph = 2000rpms for me thats with GPS and EFI Live scanner.

496chevy

thanks, its 2wd, 255/70/15 ~ 28.5 or so tall tire nor more than 29 for sure. at 2000rpm i would say im at 65-low 70's.
i kinda feel bad for posting such a cheap post... i go to work 6 days a week and 30 hrs of school a week (for reference purposes ) and i just want the cliff note on the how to.
prety much i have the stock tune file on there and the only things ive modified are the the:
trans shift times .300 across the board.. well heres my *cough* tune file... im trying to learn as much as i can in a 30 minute spread before i go to bed.
thanks,
clint