How much MPG did y'all gain from your lean cruise tunes?

 

im running about 15.2 now.. havent had time to change it but 15.8 is what im shooting for. I get 18 on the highway now..with 370, big cam, and 4.56s

 

How do you guys with all this motor work and bigger motors getting better MPG than my basically stock 5.3? I realize it's 4wd with 33s, but I'm getting like 14-14.5mpg being easy on it.

 

it get 20-21 straight highyway at 15.5 AFR... in city it drops to about 15 due to my damn converter.....

 

Usable power band, no crap stock tuning, and lean cruise. There is this little thing called spark advance too. Its some pretty wondrous ****.

I've tried targeting as lean as 16.5:1 but running that lean it really starts to work against you. Some engines will do it, some won't, mine won't. The engine starts to loose enough power that it has to work harder and in the end uses as much or more fuel then running it at something sane like 15.8:1, not to mention how high the EGTs can get running really lean. I'm going to try 15.5:1 on my 95 and see what happens. There for a while I was getting in the low 16 mpg range running 70 then I tried 16.5:1 and got something like 15 mpg and it was hating the head wind.

 

It's the tires man. I lost 4 mpg when I went from 245/50/20s to 305/50/20s. The weight and added tire height made a huge difference.

 

Yea heavy wheels and tires kill it. my last setup got like 15 maybe a hair above on the highway and around town 11-12

 

Yeah I know the tires are hurting it, but I only lost about 1-1.5 from going from 285/75-16s to my 18s. Lost some performance too. But like dirt track racer said he's getting 18 on the highway with 4:56s

 

Is lean cruise the only way to gain much more fuel mileage over the regular tune? I know a couple years ago when I was reading up on tunes, waitforme tunes were advertising a fuel mileage tune that was suppose to net 3-4mpg over stock. Im not so sure about those gains though. If thats true could I tune my tow/haul to race mode with more aggressive tuning? Or does tow/haul only affect shift points?

 

If it makes you feel any better I can only get 14-15 mpg highway out of a H/C 6.0/3600/80e/4.10s. In town I get 7-11 MPG.

Back when I had stock 16s and tires, stock 6.0, 4l60e, and 3.4s I got 23 mpg highway, no ****.

I honestly feel that the the 285/60/18 tires on all 4 corners made the largest difference in my fuel economy than any other factor. Hell, when I got them on I lost so much performance I HAD to swap to 4.10s. Once I got the 4.10s in it felt as peppy as it was with the stock wheels and tires.