B1901 Max Allowed Engine Torque

[SHOGOR]

2002 Silverado 8.1L L18 with 5 sp Allison auto trans.

Anybody know if the value of the cell B1901 is merely used for calculating in other areas or does it actually limit your max torque?

I have disabled axle torque limiting B6601, but the value entered into cell B1901 only seems to affect how the trans up-shifts. e.g.: value of B1901 set to 50 and the trans bangs the shifts very very hard, if you set it to 640 which is max, it up-shifts very very soft. I assume it affects the % of torque reduction on the up-shifts, but I want to know if setting B1901 to 640 max allows more engine torque or is it really infact limmiting more torque?

thanks.

[oztracktuning]

I have heard that this B1901 has been used to control fuel pressure in some Australian utes. Can anyone verify and clarify this.

[Whippled 496]

2002 Silverado 8.1L L18 with 5 sp Allison auto trans.

Anybody know if the value of the cell B1901 is merely used for calculating in other areas or does it actually limit your max torque?

I have disabled axle torque limiting B6601, but the value entered into cell B1901 only seems to affect how the trans up-shifts. e.g.: value of B1901 set to 50 and the trans bangs the shifts very very hard, if you set it to 640 which is max, it up-shifts very very soft. I assume it affects the % of torque reduction on the up-shifts, but I want to know if setting B1901 to 640 max allows more engine torque or is it really infact limmiting more torque?

thanks.

Finally!!! A fellow 8.1L/Allison guy. My tune originally had MAX torque set at 500, i changed this to the MAX of 640. I noticed no differnces when scanning engine requested torque or demanded engine torque. Those were the only two numbers i tried though. I was of the understanding that NOTHING in your PCM programming would have any effect on your tranny functions when you have the Allison like we do. All shifting functions need to be programmed via the TCM. Have you looked at your TCM file yet?

So your saying when you changed the MAX torque setting to "50", it effected the shifting firmness? Thats interesting. HAve you looked into how to reduce torque management within the Allison yet? Do a search for my screen name and the posts i have made, we probably have a lot of the same questions. We are in a huge minority here because we have a GAS/Allison setup, where as 95% of the guys with an Allison have a diesel. I still dont even nderstand why we have a "transmission" section in the PCM interface when it has no effect on our tunes. Thats why we have a TCM, so why the redundancy? I have asked several times and sent PM's to both ROSS and PAUL asking why we have tranny sections in the PCM file and if changes made to them effect anything at all, but have not heard back from them yet. I will let you know when i do.

[oztracktuning]

It seems the Holden engineers used this table to control fuel pump voltage. They set it to 135Nm and anything below this in torque the pump drops voltage - above it everything works fine. If you change it higher it drops the pump voltage and the car will struggle to provide enough fuel.

Good if someone can add something about this table.

Does it effect anything else - like transmission changes etc.?

[Delco]

It seems the Holden engineers used this table to control fuel pump voltage. They set it to 135Nm and anything below this in torque the pump drops voltage - above it everything works fine. If you change it higher it drops the pump voltage and the car will struggle to provide enough fuel.

Good if someone can add something about this table.

Does it effect anything else - like transmission changes etc.?

It is only wired to the fuel pump controller on the Aust utes , they just used the code to quieten the pump , the yanks have it on the truck gearbox control

[SSpdDmon]

This doesn't affect the "yank" f-bodies, does it? I know we all up the Max Allowed Torque to it's max. But, no one ever explained why...

[TAQuickness]

I'm going to have to give this a try on the drive home.

[joecar]

What happens if you down it (F-body)...?

[TAQuickness]

Not sure yet. Still stuck at work :(

But, I was thinking it may not have any effect with a hotwire kit. I haven't looked at the schematic for the fuel pump in a while.

[TAQuickness]

I changed B1901 back to the stock setting and didn't realize any difference. But, I haven't had an opportunity to really get on it either. When opportunity permits, I'll get some before/after logs posted.