Power loss offroad

Background: I'm on 40" tires, supercharged, regeared to 4.88s, and have a rear air locker on my Tundra.

This happens maybe 5% of the time I'm on a technical rock crawling trail but the truck completely gives up as far as momentum goes. The engine runs but I can floor the pedal and get no RPMs going. It typically happens when I've stopped on some rocks and there's a giant boulder or two behind (or in front) of one or two of the wheels and I'm going uphill (either forward or in reverse). I'm talking boulders that are over half the height of my 40" tires. Even with the rear air locker the truck wouldn't budge.

We disconnected the battery for a few minutes last night on our trail run and I think it fixed it but I'm not sure since there wasn't too many hard obstacles left to get hung up on; doing this resets the computer's learning of your driving habits and other knowledge.

 

So when you hit the gas, the engine does or doesn't rev toward redline?

 

Doesn't rev at all.

 

That squashes my torque converter failing theory.

 

and in 4Lo all the Nannies are turned off iirc.

 

Traction control or stability control. I found you have to hold the traction button down to disengage it. Even with 4lo.

 

Fuck. I really hope that's not it. I do forget sometimes to completely turn it off after going into 4-low, haha.

 

To clarify, I normally do the "1 press, 3 second hold, 3 second hold" while in 2-high off the bat when offroading but sometimes when I go straight to 4-low I forget to do the extra 3 second press if I didn't do it initially.

 

It may habe something to do with that. I remember once in mud I could hear the brakes doing there thing and I believe it cuts power to the engine at the same time.

 

https://www.youtube.com/watch?v=MsW44QboqCg

Also.. here's exactly where it died last night. This is a video from the perspective of the YJ that was following me (ie. you'll see my truck in front of him) and the first part of the video shows where I got stuck; I ended up winching out a bit since I had no revs backward or foward. It's a completely off-camber spot while going uphill and barely wide enough for Jeeps so I was riding the rocks and at one point when my revs vanished my passenger side was half an inch from the rock face on the right -- I did tape my passenger rear door a bit down to the metal (ie. not a dent but the paint got eff'd).

Edit: His video doesn't really show the fact that as I got out of that first part I actually made the obstacle easier by breaking down some of the rocks.

 

Let us now if thats the case. My Taco doesnt have the nannies so I originally thought the Tundras 4lo would cancel them out...nope. kinda frustrating.
My tundra will never see trails like what youre driving but its good to know.

 

Man!!! You guys go up rocks n shit like that in the tundras .. lol.. way to tight of a squeeze between those rocks for me

 

I almost cried when my truck got keyed for fsakes. Lmao

 

Haha.. this might trigger you guys then.. this was from the trail run.. I have 3 or 4 other spots with clusters of scratches like this all over the truck but this is the first one down to the metal..

 

Smart brake acting up? Are you holding the throttle less then 25% and letting the brake up ?

 

Don't think it was the brakes because that wouldn't explain the 0rpm -- or I could be wrong.

 

Lol whatd you wash it with? a rake?

 

Don't we all use sandpaper to clean the grime off our rigs? I hope I'm not the only one..

 

If you are on the gas first and then tap the brakes (while still on the gas) this will activate Smart Stop... engine will lose power and go to idle. But if it's going to 0 rpm like you said, i have no idea.

 

Yea, it's not that. I mean I'd be at full stop to hold the truck from rolling back but then I let off completely and step on the gas (ie. all the way to the floor) and get 0rpm; I wasn't two-stepping the pedals like some obstacles require.

 

I used to race my 2011 supercharged Tundra. I can tell you that anytime I put the truck in 4 low with both nannies off the minute I floored it the computer simply cut the power. I tried multiple times to fix it and finally decided to run it in 4 high with the nannies off. I came to the conclusion the transmission couldn’t shift fast enough to keep up with the engine when it was in 4 low. Thankfully it happened during time trials instead of actual races.

 

I put mine in 4hi on a gravel road just to see if it worked, does this allow me into the 4x4 club? Seriously though, I brushed some azaleas in the yard with my MGM and about shit my pants when I saw the dust stuck to the lines of dew down the side. thought it was scared for life.

 

i'd be willing to bet it was traction control, i've forgotten to turn it off a few times off road and always smack myself in the head when i figure out that was it.

 

@Spvrtan were you able to track down the bugs?

 

I have experienced the same phenomenon. Both times I was backing up a steepish hill. Once was in mud, once on dry dirt. First time I was in 4wd with all the nannies off. Second time 2wd all traction aids engaged. Both times I was backing up, lost momentum and stopped. Once stopped, I could not get the engine to rev and break traction. It was like the tuck sat down in the middle of the trail and refused to go any further.

I think the only solution is to convert to 6 speed manual and or, carry more speed....

 

For reference, truck is N/A, 33s, stock gearing.

 

Whenever i am in 4lo i always go to manual shifting and never had my truck do that.
@Spvrtan what trail is that? I wanna run it.

 

3 steps

https://m.youtube.com/watch?v=Z_rtr_qcbKc