Umm no need for a 10 thousand dollars whatever but the proper way to get good readings is to disconnect one of the o2`s and hook up the AFR gauge. The PCM will still rely on the second o2 . I haven`t had a chance to do that yet.

Dennis, I thought about that but it will throw a code if it doesn`t go into closed loop within a certain time frame, I get no codes.
I talked to Paul B. today and he says he can`t get 10mpg on his 8.1l suburban either . I figure same gas mix same temps , should be a good comparison. So you sure about that 15mpg figure, were you going downhill the whole time??

Is that on the truck's computer or calculated by hand?

I don't know anyone with that. But the EFI live stuff is interesting to me. I'd like to learn some more about it.

My V10 Ford would get better than 10mpg. I could get 13 with that truck on the highway at 65mph. It was a 3.73 SRW truck.

I bought a 2004 4x4 2500 suburban 8.1L - 3.73 gears 9 passenger 3 years ago with 120k on it. I tow a 31' travel trailer with it and rolling we are at 17k to 17.5k. Pulls the camper great all over, been though the hills of Pa also. Towing we run about 8.5 to 8.0 mpg. Driving it empty on the highway we will gt 14 mpg, but we average around 11 on our town driving. Been tracking it by hand over the past 3 years.

I liked it so much, I bought a second one to tow the boat or as back up. Same thing, same color, same year, same engine.... Serial numbers are only a few off. Except it just turned 63,000 miles this week. I love them!

I put 5 to 6k miles a year on them, so one Mobil 1 oil change a year does it at $35 with filter plus $25 of oil it eats every year. I added a forth row seat so it seats 12 people, which helps on long trips with 7 kids! And I am upset that the tank is only 38 gallons as my daily driver is a 1/2 ton burb with a 42 gallon tank?!?! What gives? And yes, I have three suburbans.

Is it a diesel, no. But I need a tow vehicle that will seat 9 to 11 people and pull 10,000+ pounds. Not many other options out there for $15k or less that have 4 wheel drive.

^^^ I`d be ecstatic with figures like that. 4gpm better.. this thread would never exist.

Efi live is a great tool for gm's and the newer cummins. It unlocks your ECm's capabilities and allows you access to a great data log set, and efi controller. It's like tuning with fast or big stuff but with many more tables and drive ability multipliers.
My srw v10 ford with 4.10's and 35's is getting about 11mpg . Like I said earlier yeah my 7.3 gets better mpg, but with diesel now up to 4.29 and regular averaging 3.45 it actually costs more to go the same miles in the diesel.

Oh, and the formula at 8,500 towing doesn't even phase it. Towing a big 10,000 pound travel trailer at 70 mph is WAY harder than pulling 8,500 of boat. I forget the boat is back there, which can be scary. Only time I tracked it with the boat is when I brought it back from jersey through PA and Ohio, I think I averaged just over 10 mpg on that trip which I thought was great.

With the cheaper fuel, cheaper purchase price and lower maintenance cost, it is a win for me as long as it will pull the load. I just don't drive enough to even come close to making a diesel worth while. Not knocking diesels, just in my case doesn't work out.

Brian

I have an 06 2500 suburban with the 8.1. and 3.73 gears.Best I've seen is 12 on the hwy. but that doesn't matter if I'm doing 65 or 80 same mpg's. Around town probably 9, depending if I can keep my foot out of it. Love the power it has. !! I use to own an '02 w/4.10's, it towed and ran a little better but got a mile or two worse mileage also.

You can't beat them for a gas motor and all big blocks for as long as I can remember have always gotten around 10mpg loaded or unloaded, running 65 or 85 it's still 10mpg!!!

you have bas azz tools for your job and i have bad azz tools for mine except this one is for emmissions and i use it for performance too..i can put the probe in a tail pipe of a boat and dont have to have a 02 bung installed..i also have several scanners because each one does differant things for all the cars..