Want to tune 08 TBSS for fuel economy

[WS6HUMMER]

Anyone have any suggestions, its a friends truck & I'm not familiar with gen 4 operating systems. He also wants some tranny tuning, I searched the repository but theres nothing but a stock tune for 08's and I think that year had a new OS. I'll take any input anyone has, thanks.

Hummer

[Sneakyws6]

08's Do Have A New Os...

Has He Upgraded The Servo In The Tranny Yet? The Tbss Tranny Will Not Take Much In Upgraded Power, Shift Pressures, Or Removal Of Torque Management Without Grenading So Be Careful With How Much You Remove.

Do Some Searched In The Tranny Section, There Are Several Posts Over There From Other Tbss Owners With Some Tranny Tunes In Them.

I HAVE A 2008 TBSS AND IT HAS BEEN FUN TRYING TO UPDATE AND SETUP THE TUNE AND THE TRANNY TUNE.

[WS6HUMMER]

08's Do Have A New Os...

Has He Upgraded The Servo In The Tranny Yet? The Tbss Tranny Will Not Take Much In Upgraded Power, Shift Pressures, Or Removal Of Torque Management Without Grenading So Be Careful With How Much You Remove.

Do Some Searched In The Tranny Section, There Are Several Posts Over There From Other Tbss Owners With Some Tranny Tunes In Them.

I HAVE A 2008 TBSS AND IT HAS BEEN FUN TRYING TO UPDATE AND SETUP THE TUNE AND THE TRANNY TUNE.

Thanks for the help, I have a corvette servo brand new un opened I found when I was cleaning @ work the other day. We may just have to put it in and try it out.

[RWTD]

Fuel Economy? I seriously doubt you'll find any better than the factory tune, tho some "enhancements" could be made to help. The PE Enable TPS is already at 87, so it takes a bit of effort to move into PE mode. Like most other trucks, it may also has a PE Enable Delay Timer (HPT doesn't show access to it - hence why most just zero out the Delay RPM, Enable RPM, and RPM Hyst.). Even the Enrichment Rate is low.

You could modify the Stoich AFR 0.00% column to be slightly leaner, tho you may find some drivability quirks because of it, and you'll want to "do the math" to richen the PE table back to get the same commanded AFR as before such change. Keep in mind, this will only affect OL (Open Loop), and it doesn't affect CL.

Another option is commanding DFCO sooner (active at lower rpms and speeds than the factory 1700 rpm enable point - you may have to modify the CylAir and TPS enable points, as well).

All in all, you can forget fuel economy if he wants overall performance, too. He bought a heavy gas hog, so he should learn to live with it.

The trans tuning is the same as the Gen3 vehicles.

[WS6HUMMER]

Fuel Economy? I seriously doubt you'll find any better than the factory tune, tho some "enhancements" could be made to help. The PE Enable TPS is already at 87, so it takes a bit of effort to move into PE mode. Like most other trucks, it may also has a PE Enable Delay Timer (HPT doesn't show access to it - hence why most just zero out the Delay RPM, Enable RPM, and RPM Hyst.). Even the Enrichment Rate is low.

You could modify the Stoich AFR 0.00% column to be slightly leaner, tho you may find some drivability quirks because of it, and you'll want to "do the math" to richen the PE table back to get the same commanded AFR as before such change. Another option is commanding DFCO sooner (active at lower rpms and speeds than the factory 1700 rpm enable point - you may have to modify the CylAir and TPS enable points, as well).

All in all, you can forget fuel economy if he wants overall performance, too. He bought a heavy gas hog, so he should learn to live with it.

The trans tuning is the same as the Gen3 vehicles.

Wow good info I really appreciate the reply/advice!

BTW: what is is a good safe stoich value, 15.xx 16.xx?


Hummer

[brianko]

Wow good info I really appreciate the reply/advice!

BTW: what is is a good safe stoich value, 15.xx 16.xx?


Hummer

For cruise, that's OK. But you're not going to achieve that, because the computer will always try to adjust for 14.7 in closed loop.

[WS6HUMMER]

For cruise, that's OK. But you're not going to achieve that, because the computer will always try to adjust for 14.7 in closed loop.

Unless you change the stoich value. If you tell it stoich is 15.11 then the computer will be trying to acheive 15.11. Correct me if I'm wrong.

[RWTD]

For cruise, that's OK. But you're not going to achieve that, because the computer will always try to adjust for 14.7 in closed loop.

That's exactly right, and I should have made mention that I was only referring to OL (Open Loop), and it doesn't affect CL. Basically, the factory O2 sensors are only accurate at the stoichiometric AFR for the fuel that you are using.

Gas = approx. 14.6x range = 450mv
E-85 = approx. 9.7x range = 450mv

Something you *can* do is modify the O2 Rich/Lean vs. Airflow table (I probably shouldn't even mention this, lol). Modifying this will allow you to spend more time above or below the stoich point of 450mv. Above 450mv = rich and below 450mv = lean.

Edit: I just did a search. Read this thread for some good info:

http://www.hptuners.com/forum/showthread.php?t=18278

And post #9 in this thread has some awesome info:

http://www.hptuners.com/forum/showthread.php?t=15606

Scroll down and read Greg's (eficalibrator) post #37, as well.

[WS6HUMMER]

That's exactly right, and I should have made mention that I was only referring to OL (Open Loop), and it doesn't affect CL. Basically, the factory O2 sensors are only accurate at the stoichiometric AFR for the fuel that you are using.

Gas = approx. 14.6x range = 450mv
E-85 = approx. 9.7x range = 450mv

Something you *can* do is modify the O2 Rich/Lean vs. Airflow table (I probably shouldn't even mention this, lol). Modifying this will allow you to spend more time above or below the stoich point of 450mv. Above 450mv = rich and below 450mv = lean.

Edit: I just did a search. Read this thread for some good info:

http://www.hptuners.com/forum/showthread.php?t=18278

OK I see, thanks for clearing that up & for the link.

[RWTD]

And post #9 in this thread has some awesome info:

http://www.hptuners.com/forum/showthread.php?t=15606

Scroll down and read Greg's (eficalibrator) post #37, as well.

[WS6HUMMER]

And post #9 in this thread has some awesome info:

http://www.hptuners.com/forum/showthread.php?t=15606

Scroll down and read Greg's (eficalibrator) post #37, as well.

Thanks again!

[brianko]

Something you *can* do is modify the O2 Rich/Lean vs. Airflow table (I probably shouldn't even mention this, lol). Modifying this will allow you to spend more time above or below the stoich point of 450mv. Above 450mv = rich and below 450mv = lean.

I would very much like to see this work. I can tell you it doesn't seem to have any effect on an '03 5.3L (I spent a few hours on the dyno trying to get this to work; the WB wouldn't budge from 14.6.) I'm not saying that it won't work, but I suspect some O/Ses won't see a benefit. Doesn't hurt to try though...

[WS6HUMMER]

I would very much like to see this work. I can tell you it doesn't seem to have any effect on an '03 5.3L (I spent a few hours on the dyno trying to get this to work; the WB wouldn't budge from 14.6.) I'm not saying that it won't work, but I suspect some O/Ses won't see a benefit. Doesn't hurt to try though...

I did it on a 99 silverado 5.3 and the owner didnt really notice a difference, I was very mild with the changes though.

[rrmccabe]

Timing will help you a little under cruise. But these things are basically pigs.

Only other thing I have done is lock the converter a littler earlier. This probably only helps me because of the stall speed I am running.

E-Fans seem to help MPG as much as anything.

[WS6HUMMER]

Timing will help you a little under cruise. But these things are basically pigs.

Only other thing I have done is lock the converter a littler earlier. This probably only helps me because of the stall speed I am running.

E-Fans seem to help MPG as much as anything.

Thanks, it has e-fans now. I also opened the DFCO windo up to 2300. We will see if it helps in about 2 hrs.

[BBA]

Anyone have any suggestions, its a friends truck & I'm not familiar with gen 4 operating systems. He also wants some tranny tuning, I searched the repository but theres nothing but a stock tune for 08's and I think that year had a new OS. I'll take any input anyone has, thanks.

Hummer

I'm getting about 2 MPG better average MPG with my 2007 TBSS after tuning. I'm almost at 15 MPG now, not bad for AWD.

The secret is positive timing at low RPMs and high airflows, getting MAF table zeroed in for lower ST/LT and changing PE enable setting to 85Kpa.