2010 Torque tables

[SASDakota]

E2701 vs. E2702

What are your thoughts? I know another tuning software I have used, does not reference E2702. Everything looks like E2701, makes me really wish I could see the bigger picture in there (pcm).

The smarter guys than me, care to toss the guy in the dark a flashlight?

[GMPX]

The Cummins calibrators can choose to base some axis's off fuel mm3 or Torque.
Regular trucks seem to use Torque, but Cab and Chassis use Fuel mm3, this is why the axis is defined as 'Load' as it could be either Torque or mm3. So yes you'll find in the regular trucks E2701 & E2702 will have the same numbers, but take a look at the C&C tunes to see the difference. Did your 'other' software support C&C vehicles for confirmation on this?

To know for certain what you are dealing with checkout -

{E2759} Injection Core, Load Axis Reference

You cannot change this, it is there as a reference only. And no I have no idea why the C&C trucks are based off fuel amount, but I am sure they had their reasons.

[SASDakota]

I saw E2759, which was very cool to have in there as it is simply insight into what is going on.

What I am talking about is {E2711}(Tq-Fuel) references {E2702} (LOAD) for an axis. While Timing, pressure, etc. Used {E2701} (TORQUE) for their axis.

This is all looking at OS# 22100538 and Cal#10350031BG

[GMPX]

What I am talking about is {E2711}(Tq-Fuel) references {E2702} (LOAD) for an axis. While Timing, pressure, etc. Used {E2701} (TORQUE) for their axis.

Correct :grin:
You can't have a Torque to Fuel conversion table (E2711) reference what it is trying to look up.

[SASDakota]

I don't see that is or that it could with what I am talking about. I'm thinking we aren't on the same page. So correct me if I am wrong, but Tq-Fuel uses {E2702} LOAD instead of {E2701} TORQUE. Then the other maps don't reference {E2702} LOAD, they use {E2701} TORQUE. Thus in my brain... makes the maps not line up when the engine operates through various rpm&torque scenarios because fuel is {E2702} Load based, but timing and turbo is {E2701} Torque based. How are they working together?

[GMPX]

but Tq-Fuel uses {E2702} LOAD instead of {E2701} TORQUE.
Ok, ignore the axis numbers for the moment.
E2710 - Torque to Fuel conversion, for a given RPM and engine torque value it needs to inject 'x' amount of fuel, that is what this table is for, figuring out the fuel needed. So here it needs to know RPM and desired engine torque (not load) so therefore it must look to {E2701} Torque To Fuel Conversion, Torque Axis.


Then the other maps don't reference {E2702} LOAD, they use {E2701} TORQUE.
E2503 - Main Injection Timing, again RPM is used, but this is where Cummins can choose to reference the 'Load' axis by either commanded fuel mm3 (result from E2710) OR actual engine torque.

So to try to paint the picture on how it all ties in it goes something like this...

B0752 - Pedal To Torque Conversion - Converts the accelerator position to a desired torque figure, in older systems like the LB7 Duramax this would just convert from pedal position directly to fuel mm3.
E2710 - Torque to Fuel conversion - Converts the desired torque value (from B0752) to a fuel amount value in mm3. The result could potentially could be used by timing etc, or just fed through to the injection control (via limiters etc of course).
E2503 - Main Injection Timing (scenario 1) - Cummins want to reference the "LOAD" axis to fuel amount NOT torque, therefore they will look to the result from Torque to Fuel to get the mm3 value.
E2503 - Main Injection Timing (scenario 2) - Cummins want to reference the "LOAD" axis to torque amount, therefore they don't care how much fuel is being injected, they want to base the timing on the amount of torque being produced.

I hope that helps, I'm not sure how else to explain it.

[SASDakota]

Ok, ignore the axis numbers for the moment.
E2710 - Torque to Fuel conversion, for a given RPM and engine torque value it needs to inject 'x' amount of fuel, that is what this table is for, figuring out the fuel needed. So here it needs to know RPM and desired engine torque (not load) so therefore it must look to {E2701} Torque To Fuel Conversion, Torque Axis.
^^ Agreed.

E2503 - Main Injection Timing, again RPM is used, but this is where Cummins can choose to reference the 'Load' axis by either commanded fuel mm3 (result from E2710) OR actual engine torque.

So to try to paint the picture on how it all ties in it goes something like this...

B0752 - Pedal To Torque Conversion - Converts the accelerator position to a desired torque figure, in older systems like the LB7 Duramax this would just convert from pedal position directly to fuel mm3. Agreed
E2710 - Torque to Fuel conversion - Converts the desired torque value (from B0752) to a fuel amount value in mm3. The result could potentially could be used by timing etc, or just fed through to the injection control (via limiters etc of course).This is where I was saying that fuel and timing go their separate ways. Because of scenario2
E2503 - Main Injection Timing (scenario 1) - Cummins want to reference the "LOAD" axis to fuel amount NOT torque, therefore they will look to the result from Torque to Fuel to get the mm3 value.
E2503 - Main Injection Timing (scenario 2) - Cummins want to reference the "LOAD" axis to torque amount, therefore they don't care how much fuel is being injected, they want to base the timing on the amount of torque being produced.

I hope that helps, I'm not sure how else to explain it.

So in short, I was correct in the sense that timing and fuel have no static relationship in that regard. I think EDA with calculated load is going to revolutionize 4th gen tuning.....

Fuel is based on: Throttle>Desired Torque>Commanded Fuel qty/RPM>Limiters>Pulse.

Timing is based on: RPM/Load>limiters>*BTDC.

I strongly question how a timing calculator can really be of any use at this point if timing does not follow fueling. Am I wrong?

[Mitco39]

Scenario 2 is alot harder to play with because the computer no matter what you put in for the main fueling tables the truck will do what it wants to achieve what it thinks is your desired torque.

On the trucks based more on a fueling approach our current mapped out EFI Live tables work nicely. On the torque based approach there are more tables hiding that you will learn to believe are there once you try and turn up the power. While in theory the torque based approach will lead to a better refinement in the tuning, at the start there are many more things at play that the ecm uses to both calculate and control the torque.


Timing and fuel does have a static (or semi static if you take into account the various multipliers). What I believe ross was saying is that the ECM doesn't care how much fuel it injects, it only cares about the desired torque and the current torque being delivered. The timing is then derived from the amount of fuel the ecm figures is necessary to achieve a desired torque. Some of us have actually been using timing to monitor the actual mm3 value until EDA comes out and we can see that number as it is calculated.

[Tarmacblack]

Good information here, thank you Ross, Mitch, and SAS for the discussion.