duffy

Yea it shifts way differently, seems to Rev higher, shifts can be very jerky..
Loss in mpg's due to the performance setting, but a huge gain in HP/torque went from about 15-18 MPG to 12 -__-

duffy

***Lol wanted to say shifts not ****s****

otto457

Good to know. I don't have first hand experience with the Diablo's. The "factory specs" a/f worries me, which is probably why the OP is running lean. This is one of Bill's graph's when he was tuning on his dyno. The stock a/f stays pretty high until 4000+ rpm. You can see the towing a/f stays a little richer to compensate for the heat produced while under load. Running a performance tune will probably be leaner in the higher rpm than the stock tune.
The higher octane Diablo tune probably pushes the envelop even more on a/f on that end. When you're at 14.5 a/f even a little variation will swing it into lean as there's no real cushion for error or extra load. Their performance tunes must map the transmission for the load which is why they say they can tow with it, but the a/f probably isn't as good as what a custom tune will do. So little room for variation and not having the correct specs is what's pushing the tune lean.
I also forgot to ask from the very beginning to the OP: does it run lean with the stock tune and have you checked all the intake and hoses for leaks? Just trying to isolate whether it is a tune issue or maybe mechanical (vacuum leak, etc) issue.

jerrybizzle

For some reason when I ran the premium perf tune I lost mpg as well. With the 87 I get about 16 average. That's with the 33s I had. If u have larger than stock size tires, u need to make sure axle ratio is correct, along with tire size and nov setting to make sure your shift points are in line. It makes a big difference.

encasedmetal

16mpg before or after the tuner?

duffy

Yea I have 33's tire size should b right... don't know enough about motors/trucks to know the right shifting points... thank y I'm thinking about a custom tune just have it done right b4 I have a broken truck in my drive way... but 4-5 bills is making it hard to get

jerrybizzle

After tuner. Duffy pm me and I can walk u thru setting it up and saving yourself some cash. Works great when its setup right. What size tires you have and what axle ratio?

duffy

Dude that would be great, don't know my axle size? How can I figure that out? I'm at work right now, ill give u all the specs when I get home
Thanks a lot

jerrybizzle

Check the doorjamb sticker under axle code. H9 is 3.55, b6 is 3.73. If something else, let me know. Are your tires 285/70/17? Need to know to figure out the nov (engine over vehicle) setting which tells the truck when to shift to od.

duffy

They r nitto terra's on 18's so I believe they are 285/70/18 like I said I'm at work truck is at home so I'm not 100% sure till I go home and look, I do know I have an afe cai and a flow master exhaust if that helps