4x4 high loss of torque when stuck

[mrjking2000]

hello all, pure curiosity if anyone knows why in 4x4 high range, when you get a ram 2500 power wagon stuck in snow, it won't spin the tires in drive or reverse to "get free" of the deep snow. You have to fight the t-case selector and get it into 4x4 low in order to move. This seems like a programming thing where it's pulling torque as the engine lugs and RPMs do not climb.

any idea where this is? curious if it's worth re-programming this while i'm in there shutting off MDS.

wasn't sure if this was transmission or engine related so i figured i'd post here.

thanks,

[white1]

Try turning traction control off. Youd thing in 4wd it would disable traction control, but for some reason in 4 hi it does not

[mrjking2000]

traction control is off, and i can also kill it 100% with the zauto tazer ram. you still cannot spin the tires when you get stuck. it's being limited somewhere.

[nmineau]

what kind of rpms are you getting? if its around 2300rpm, its simply all shes got in a stall condition.

[mrjking2000]

yeah it's about 2000 or so and it bogs down. i'd expect this giant 6.4 hemi to be able to burn rubber for days when stuck like any other truck can. i figured it was something limiting torque.

[nmineau]

yeah it's about 2000 or so and it bogs down. i'd expect this giant 6.4 hemi to be able to burn rubber for days when stuck like any other truck can. i figured it was something limiting torque.

the 6.4 will stall at 2400-2600rpm WOT at sea level on the 6 speed on a stock tune. if its only reaching 2000rpm, and the dropping from their, then something is cutting power like crazy, or something else is wrong.

It Should be pretty easy to simulate with a 4wd/full throttle / full brake/ stall speed test to see if you can reach full stall rpm or not (dont do this long in fear of toasting the torque converter fluid.

If you said you strapped the truck to a tree, and were on bare pavement in 4wd, trying to pull it down, and it wouldn't spin in 4 hi, i wouldn't be suppressed cause its so heavy. but in the dirt or especially the snow, you shouldn't need 4 low to break the tires free if its getting full power.

i think something is cutting power like crazy, could be the stability control system, may be the power waggon has some weird torque managment in 4hi that the non power waggons dont

[nmineau]

the 6.4 will stall at 2400-2600rpm WOT at sea level on the 6 speed on a stock tune. if its only reaching 2000rpm, and the dropping from their, then something is cutting power like crazy, or something else is wrong.

It Should be pretty easy to simulate with a 4wd/full throttle / full brake/ stall speed test to see if you can reach full stall rpm or not (dont do this long in fear of toasting the torque converter fluid.

If you said you strapped the truck to a tree, and were on bare pavement in 4wd, trying to pull it down, and it wouldn't spin in 4 hi, i wouldn't be suppressed cause its so heavy. but in the dirt or especially the snow, you shouldn't need 4 low to break the tires free if its getting full power.

i think something is cutting power like crazy, could be the stability control system, may be the power waggon has some weird torque managment in 4hi that the non power waggons dont

when i said they stall at 2300, thats a 5.7 hemi. the 6.4 pushes harder against the convorter in that situation, reaching close to a 2600rpm stall

[mrjking2000]

yeah that's why i'm pretty sure something is pulling torque. you can't spin the tires at all framed out in the snow. i have no idea where that would be located... engine or transmission tuning.

[nmineau]

yeah that's why i'm pretty sure something is pulling torque. you can't spin the tires at all framed out in the snow. i have no idea where that would be located... engine or transmission tuning.

post your tune file and ill look at it and see if i can find it

[mrjking2000]

post your tune file and ill look at it and see if i can find it

thanks a ton! I licensed the transmission file before I pulled the PCM so there are two.

2019 power wagon engine only - STOCK.hpt2019 power wagon trans only-STOCK.hpt

[f.creek-ranch]

If you got slip, you only got 150Nm , thats what your TQ management of the tranny says.

ESP and Transmission TM in PCM shutting off throttle fuel and spark.

Modern cars uses a lot of things to cut power, some of them even if you disable ESP at button.

Disable torque management step by step and look what makes the most loss.

Sometimes it helps to disable parts of TM like only fuel cut, wich means the most.