Any idea why this OEM table is so strange?

[Gone Nomad]

Does anybody have an educated guess as to why this 3500 LMM van high altitude table (in the oem tune)

is so different than the low & medium altitude tables,
considering that none of the tables in an LMM 3500 pickup or 5500 Topkick are like that?

Thanks!

 

[Gone Nomad]

OK, let me ask what should be an easier question.

When the "Tow/Haul" button is on, does that cause the ECM to use a mode (A, B, C) as shown in the charts above that is different than the normal mode?

Or does "Tow/Haul" only affect how the TCM controls the tranny?

 

[GMC_2002_Dmax]

Torque based fuel is how the ecm "fuels the truck" along with pedal position to desired torque, fuel pressure, main injection.

Pedal Position to desired torque is the throttle table, those numbers are then used in the torque based fueling to look up the fuel rate mm3, then that looks up the actual fuel in the Main injection table and the fuel pressure table is also referenced so the ecm knows at what pressure to deliver the PW and then of coarse timing is also referenced along with any multipliers or limit tables.

Air is thinner at high altitudes, so fueling and timing and boost is altered based on Altitude.

I know a lot of tuners can't get anything to run at higher altitudes like they can at sea level, once you understand how everything works and why then with the proper changes they run just as well up at 5000 feet as they do at sea level.

It just takes a lot of time to understand how the pieces of the puzzle fit together.

 

[Gone Nomad]

...I know a lot of tuners can't get anything to run at higher altitudes like they can at sea level, once you understand how everything works and why then with the proper changes they run just as well up at 5000 feet as they do at sea level.

Thanks...

Just to clarify, this table is from the OEM GM tune.

The other OEM GM LMM tunes don't have such a weird map in this table.
I guess it's difficult to guess why they made it this way.

.....

 

[THEFERMANATOR]

Maybe you should submit a report to EFILIVE about it. It could just be a mis scaled table as it does happen. I know that in an 02 TCM operating system the 4-5 shift is mis marked for tow haul mode, or how tow/haul and 4 low are reversed.

 

[Gone Nomad]

Maybe you should submit a report to EFILIVE about it. It could just be a mis scaled table as it does happen.

In other words, the EFILive software could be misinterpreting or misrepresenting the actual data that is in the oem calibration?
I didn't think about that possibility. I will pose the question directly to EFILive.

BTW, here's the table data that goes along with that map:

I know that in an 02 TCM operating system the 4-5 shift is mis marked for tow haul mode, or how tow/haul and 4 low are reversed.

So I guess that also answers this question:

When the "Tow/Haul" button is on, does that cause the ECM to use a mode (A, B, C) as shown in the charts above that is different than the normal mode?

Or does "Tow/Haul" only affect how the TCM controls the tranny?

IOW, "Tow/Haul" changes how the TCM works, not the ECM?

 

[THEFERMANATOR]

For LMM's there is 3 different throttle based fuel tables, but I never logged it to see if it used it just 1 of them or changed which table based off of tow/haul or not.