Power loss offroad

I haven't yet. I'll try reproducing the issue again without all the nannies off the next time I'm on a trail and then turn them off.

 

It's Sidewinder in Corral Canyon:
https://www.trailsoffroad.com/trails/2214-sidewinder-corral-canyon-ohv-area

 

I’ve had this same issue a couple times. It’s weird, my truck wouldn’t gain rpm’s even with the pedal to the floor. It’s like it was in limp mode. One time I had the traction control fuse removed and it still happened.

 

Hello, first post and reviving an old thread here but I'm running into the same issue as @Spvrtan and wondering if anybody has any more info or a solution. For reference I have a '17 TRD Pro with 4:88's. 35's and an Eaton rear locker.

In 4low, even with the additional push of the button to get the "traction control off" text on screen and the nannies fully off, the truck gets hung up off road and the throttle becomes unresponsive. Usually when the wheels have to overcome a slightly taller square edged obstacle.

Been searching other forums trying get more info and it sounds like there's a "throttle interrupt" that gets triggered if any brake input is detected—some have had weird throttle cut-out issues and attributed it to LED tail light bulbs but I dont think that's what's happening in my case.

There's a camp spot I frequent and that requires going up a rock step and it's pretty mild like maybe a foot tall. I roll up to it and bump the front wheels up no prob but when the rear tires come up against it, and I give it some gas, nothing happens. No rpm's, no wheel spin, nothing. I can back up and usually bump up it with a little run up but I'd rather crawl up it and the truck should be able to do this. Engaging the locker doesn't help… it's not like the truck can't find traction—the throttle just isn't delivering any power.

So maybe when the wheels hit this kind of obstacle the truck thinks the brakes are being applied? I cant imagine who in their right mind would program the sensors or computer that way.

Anyway, this issue sucks and is frankly an embarrassing shortfall of an otherwise awesome vehicle. Wondering if there's a specific sensor that can be disabled or?

Hoping someone has a fix.

 

I’m not an off roader but I remember reading Matt Wilson from formerly OVtune, now VFtuner explaining what this is. He was able to disable if requested through his software when getting the truck tuned by him. He has since been banished from this forum but you could inquire with VFtuner.

 

Interesting, thanks.

 

@Cruzer Has been working with HPtuners software to disable the 4low limiter as well. I think he is familiar with what it is maybe he can chime in here for you guys

 

I think the only person that would be comparable to the situations you put your truck through and roughly same type of equipment you have (40s) would be @Cruzer maybe he can chime in

 

Lol great minds and all.....

 

HP Tuners can correct it.

Below is the throttle angle (86deg is max angle) for "1st Gear 4WD Low" for a TRD tune (presumably same throttle limits as stock), and as you can see over 800rpm the ECU limits the amount of throttle to about ~30% even if you're foot on the floor. You just go in and set everything to 86deg and you have no throttle limits then.

 

Unfortunately, that's not the only fix. I had mine maxed out at the Rubicon and it still wasn't able to give me the power I needed.


However, I think I do know what my problem was. Under Transmission I had this setting, where 6500 is the max rpm. My 50% and lower pedal position was just too low. Even though I was flooring it, it was just too late to overcome it. I was trying to prevent myself from snapping the stub shaft in the front diff so I thought that this profile would keep me from accidentally spinning it too much. It did not work.


So now I changed it to this. Eventually, I will dial it down and find a sweet spot so I don't break shit.


EDIT: Oh, and to explain what's happening.... the OEM tune is configured/designed to limit the power to the wheels so that you don't break axles, stub shafts, or anything else down there.

 

With these limits as you are showing, does this mean that guys who are putting the hammer down in 4lo such as competitive truck (sled) pulling are really only getting 30% throttle when holding it pedal to the metal? If so that’s a drag, so much more power on the table that isn’t harnessed for those situations.

 

If their truck is untuned then presumably yes. And as @Cruzer points out, there are multiple places inside of HP Tuners where there are throttle, torque, and rpm limits. Turning off traction control is really just telling the truck that you are okay having the tires spin freely, but there is a lot more going on to prevent the truck hurting itself which can be turned off. I am sure OV (VFT) has all these features as well, but I left that train awhile ago.

 

I wonder how much removal of these limits is almost standard protocol for the common tundra tuners. I’ll have to ask DAP where he sets these limits. If I ever need that power and can’t access it I’d be bummed.

 

A few years ago I was camping in the desert with some friends and the tundra got a little dug into the sand and I didn't think anything of it. Someone pulled in in front of me, and the next day I go to back up to leave and in low range floored I couldn't even get the tires to spin or do anything. It just sat there revved up a little and that was it. A friend with a little 4runner that was 20 years old had to pull me out with my big supercharged 5.7 Tundra. Honestly can be dangerous how much it limits the power.

 

Appreciate all the info.

Guess I need to look into a tune.

I get that there are limits in place so you don't break stuff but feels like the throttle literally becomes disconnected in situations that are far from extreme.

I've owned 3 different 4runners over the years (still own a '13) and never have experienced anything like this.

 

I’ve had this issue for a long time now. I run 38” tires and 5:29’s… I either have to bump the vehicle or sometimes I have created a check engine, light by disconnecting the map sensor with the key on. For some reason it seems to shut off the throttle cut if you have a hard fault like a map sensor. I’ve added a supercharger and it happens a lot less now, but it still happens. Mines a 2019 so the computer is pretty locked up and I don’t think I can get a tune other than the Magnuson tune. for those of you who want to try have the check engine light I may be worth a shot.

 

Lots of tuning options, 2019 has been unlocked across HP Tuners and VFT for awhile.

 

Thanks, I’ll check it out.

 

I was just curious if you were able to eliminate the loss of power with just the tune? I can’t seem to find anyone else who has solved the issue.

 

Nope. I bought a 4 speed Atlas transfer case instead.

 

I saw that on your build thread, awesome build! I saw on your YouTube walk around that you also did a lot of wiring to try to trick your truck into thinking it was 2 wheel drive so you could use tow function and get torque back. So that didn’t work either? i’m trying to find someway to bypass the system to get torque back but nobody has an answer yet. Not too many Tundra owners rock crawl that much.

 

Tricking it did work. Since I deleted the front diff stub shaft I didn't have to worry about manipulating the ADD. Chopping up the wires to the 4WD ECU wasn't fun. If I had to do it again I'd find a junkyard 4WD ECU to create a bypass adapter. I had a notepad with all my scribble dibble on it... I threw that away along with my experimental switch . From what I remember I had to trick the TC switches/sensors before starting the truck so that they saw the 2wd voltages. I think the 4HI I would toggle open so that it never received a signal. Then I used a SPDT switch to manually shift between 2wd>4hi>4Lo. There's a coil that you don't need to mess with, which I think helps with going into 4HI when the truck is moving.

 

Thanks for taking the time for a detailed response. My stub shaft delete is in process and I’m just waiting on parts as I went with genuine Toyota parts. I was hoping that I could somehow tune it out. I’m pretty good at electrical so I’m gonna download the EWD to see if I can figure it out. Thanks

 

What is the part number for the oem LC200 intermediate shaft? I’ll probably get the oem one too.

 

Shaft, Diff Side Gear Intermediate, No.2

Part Number: 41337-60020

 

It's only $230.. not bad. Gonna order me one.

 

They said mine was on backorder, but it came in today. Looks pretty strong