Looked at a tahoe owned by a GM tech, and was told it had some kind of program or tune for the transmission that allowed it to get 18-19 mpg city and into the 20s on the highway but does lower overall torque. Said it is a factory tune, but is hard to get someone to do it and you have to know the right people to get it done. Can black bear do a tune that will get similar numbers? Have a long trip coming up and looking to get the best numbers possible.
Transmission Program/Tune
- Thread starter SP543
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Sounds like hog wash to me. There is maybe a few things to help mileage like prevent downshifts from happening as quickly and upshifting early but I doubt it would make a huge impact. On the hwy you could make the converter stay locked under more throttle and that may help on long trips, but again I don't think it would yield stellar results. Plus a stock tune is about as conservative is I'd like it anyway.
FrankU
Full Access Member
One can expect better fuel mileage with a better shifting transmission out of a Black Bear tune. I did , and recommend the tune.
For starters their is alot of torque management, as well as alot of the time the downshift tables are skewed (this makes for alot of unwanted heat from the trans) Shift times are delayed and fuel maps are not perfect for what the engine wants, Timing is lazy as well so that we can burn the horrible fuel they supply us nowadays. These are things that a tuner can remedy and you will notice a difference. But will require some better fuel run thru it.
I just moved the fuel economy on the wifes 04 denali we just purchased from 15 to 18.6 out on the highway and I am not completly done yet with the tune. This is hand calculated not from the faulty DIC. This was from changing me changing the tune.
The factory does a good job with the tune and with it the rig will run good everywhere but they are conservative and they have to keep things dialed back to keep big brother happy.
It has actually been a fun project just to see how good I can get the mileage. I am hoping for the magical 20 mark out on the highway when done.
I just moved the fuel economy on the wifes 04 denali we just purchased from 15 to 18.6 out on the highway and I am not completly done yet with the tune. This is hand calculated not from the faulty DIC. This was from changing me changing the tune.
The factory does a good job with the tune and with it the rig will run good everywhere but they are conservative and they have to keep things dialed back to keep big brother happy.
It has actually been a fun project just to see how good I can get the mileage. I am hoping for the magical 20 mark out on the highway when done.
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FrankU
Full Access Member
Izcain just about covered it. But I had BB do a on the spot tune for premium gas. I get better fuel mileage and more power (SOTP) under the peak. With regular gas and no detonation on my read out.
My 5.3 runs very well.
Cons.
Cost , no big deal well worth it.
They upped the WOT shift point to 5900+ (a bit to high IMO)
Put too much pressure in the transmission , hits 2-3 shift too hard.
Funny you just mention that. I recently just took out some rpm out of the 1/2 shift. Stock was 5600 on 1/2 and 2/3 was 5200. I put the 1/2 to 5200 to match. The engine just doesn't make/hold power long enough to justify the higher rpm shift. I like it much better.
