Torque based Fuel Maxes out at 886

[Kirker912]

How does the ECM figure fuel over 886 ftlb if the torque based fuel maps max out at 886? I've been trying to command 1400ftlb in B1161 petal position to desired torque and when I log a run I never see anywhere near that value.

Truck is an 07.5 LMM on 12628594 and obviously built trannie. Trannie tune is maxed out in the torque tables. I only see requested torque reduction on shifts.

Appreciate any thoughts or information. I have logs and tunes to post if anyone is interested.

[Wheelz]

Maybe there is a better way, but what I would do is modify the duration to mm3 values to be what you want (thereby causing the actual injected mm3 amount to be incorrect) and you use torque based fuel to command a mm3 level that corresponds to the duration you want

Then you would have to modify your torque reduction tables as you need

[Kirker912]

I thought about that for a bit but didn't start down that road in hopes that someone had a better plan. I see two ways to lie to this. Not to aruge but to understand... Why do you change duration instead of changine the torque based fuel?

Route 1: Lie on the petal position to desired torque and have it max out at 886 and then lie on main injection pulse to make a request of say 3214mm3 actually inject 5000mm3 because of the longer pulse.

Route 2: Lie on the petal position to desired torque and have it max out at 886 and then lie on torque based fuel to make a request of 886ftlb actually produce 1400ftlb.

Numbers are just guesses off top of head to point across. Real numbers to come after we work out the theory.

[Wheelz]

If it was a cummins ECM I could see route 2 easier. It lets you customize your axis so you can command however much mm3 of fuel you want, and desired torque. Since you can't rescale the axis in the lbz ECM, and your torque based fuel axis maxes out at 886, that's why I recommended what I did. I would love to know a better way to do this

[THEFERMANATOR]

As soon as you modify tuning to go beyond what the stock tuning was set-up for, then forget the torque numbers being accurate. If 886 is as high as you can go in the lowest table you can call for, then make 886 your max and work off of that in your other tables.

[Dmaxink]

As soon as you modify tuning to go beyond what the stock tuning was set-up for, then forget the torque numbers being accurate. If 886 is as high as you can go in the lowest table you can call for, then make 886 your max and work off of that in your other tables.

Very good info, I stressed this hard at the efi classes!

[Kirker912]

Ok back to the computer tonight and I'll start working up some new fuel tables and have the petal position to desired torque max out at 886.

Kory, One of these days I hope to be able to attend one of those classes. I've learned a lot over the last few years but as I build more HP I realize how much more I need to learn.

[THEFERMANATOR]

The best way to describe the torque tables is if you have ever tuned an LB7. the throttle tables and several others can be set to call for 200MM3 of fuel, bt the fuel tables themselves top out at 100. So any changes made to call for more do nothing. I've had people criticize tunes I've done for them because I only call for 102-105 MM3 of fuel in LB7 tunes, and I tell them that by commanding more doesn't get you more. So why make the tables go so far beyond the area where they are meant to stay in. Once you hit 99.9, it's good, so I just go a little more to make sure it maxes out.

[Dmaxink]

Good info for sure! Mine is actually even a little lower than that! I don't care what it hits as long as it gives me my desired pulse, rail, and timing.... Trans stays happy within known values :-)