No turbo boost in 4Lo?

I spent a few hours today in 4Lo on a rocky trail. First time I've used 4Lo in my new 4G Tacoma, but have used it many times in other trucks. I noticed immediately that the throttle response was deader than dead, and I figured that was just how Toyota programmed it and I would have to get used to this annoyance.

But then as I kept driving it, I noticed there is ZERO turbo boost being created (as displayed in the gauge cluster) even when making a long, sustained hill climb in 2nd gear and about 4000 RPM. At some points the hill was so steep the RPM was dropping despite full throttle. This absolutely would not happen if the turbo was making boost. As soon as I switched back to 4Hi, everything was back to normal and you could pull a freight train with the torque of this turbo motor... This behavior was consistent every time I switched in and out of 4Lo.

Anyone else notice there is zero boost registering on the gauges in 4Lo? I have a manual transmission but I'd be interested to hear from anyone who has extensively used low range on the 4G.

 

Likely limiting throttle body opening. Without enough airflow, no boost…

 

Just think about what you're asking for lol

The truck already limits boost by gear to not break stuff, it's going to limit that even further in 4Lo so you don't demolish your drivetrain by trying to launch your 4500lb truck at a 10:1 crawl ratio LOL

The throttle response feels dead because aside from limiting boost in 4Lo, the truck can't even build it in 4Lo because you blow through the RPMs in 2 seconds

If you're in 4Lo it's not an annoyance, you just need to go slower. If the terrain requires 4Lo, slow down.

I've driven up a mountain in 4Lo and it does fine, shifts up and you can cruise along at 10mph or more with the torque converter locked. Cuts down on trans heat a lot.

OTT guys claim to unlock full boost in 4Lo but that's pretty dumb Anyone who launches their shit in 4Lo deserves to blow up their CVs/driveshaft etc

Edit: If anyone does launch their truck in 4Lo, with the OTT, please brake boost it and PLEASE record it. I want to laugh at you when your driveshaft flops off and your CVs explode!!

 

Same as 1st gear, limits boost likely to prevent the drivetrain.

I'd love to drive a tuned 4th gen with 1st gear uncorked but I wouldnt want to own one with the tune.

 

Would be sweet to see a 4G tug of war with an ecoboost F150, see how long it lasts before shit starts breaking

 

I'll admit I have been drinking so my memory is foggy, but isn't this TFL all over again?

 

Hella torque vs brake rotor (ATRAC/MTS) and they nuked the front diff lol

Toyota responded by just reducing the power (probably by just boost by gear / less boost if low range engaged) output.

I've only been tripoded hard enough for ATRACT to engage once and I immediately backed off and took a different line because it felt like it was going to break something.

 

It works great. My use is task or work vs hobby/fun oriented but that also means off road (non paved) use. For also having to do road driving,

Maybe explain what you are after? My experienced is the 4x4 modes, general drive modes and tow mode adjust things just fine for the job at hand. Sport mode for people who race to stop lights, and the others are good for work and truck tasks. It's pretty sweet to have it capable for off road work, errands, and towing and be a nice handling rig that can get some decent fuel economy.

 

I'm waiting for a tuned 4th gen throw a rod through the block and someone call it an unreliable POS

 

Meh, just a newly added inspection port.

 

I believe the OTT tune removes the boost limit in 1st gear (perhaps even in 4LO). Someone correct me if I'm wrong.

 

I'm still waiting for mine to toss one out the block... but clearly mine's better cause I do get boost in 4Low

 

Soon...

 

So far, no one has attempted to respond to my direct question, "Anyone else notice there is zero boost registering on the gauges in 4Lo?"

Instead, a couple red herrings were thrown around. I will address these:

• What are you doing, tryin' ta race in 4-LO buddy??? -- No, pops, I'm trying to drive up a really steep hill on a loose surface where you need to keep your speed and momentum up. Crawling up it in 1st gear, low-range, is not a viable solution. Nobody here is trying to "do a drag race" in 4LO. Get real.
• This is just like TFL!!! -- Not at all, champ. They were crawling up and over a sheer rock ledge with some wheel slippage and ATRAC engaged, which had some faulty programming that resulted in the system activating the brakes to control wheel spin in a way that grenaded the front diff. My scenario / use-case is nothing like the video (I watched it).

I would love to hear from anyone who can explicitly confirm (hopefully with the manual transmission) that they observed, or did not observe, any boost building under mid- to full-throttle in low range. I will also drop a line to the OTT guys to see if they have a solution. If nothing else, I will try attacking that hill next time in 1st gear, hi range, so that I have full use of the ENGINE POWER that I paid for.

 

What does your owners manual say?

 

Did you find something useful in there? I read through the "Operation of the 4WD system" section again just now, and there is no mention of a deliberate reduction in engine output in 4LO or any other advice or guidance relevant to the situation here. I also did quite a few keyword searches throughout the manual looking for other situations where engine output is deliberately reduced. None apply.

 

I appreciate the sentiment, but I don't think that describes the outcome here. The throttle tip-in on the 3G Tacoma with the V6 and the manual, in 4LO, was pretty strong and you could unintentionally take off quite abruptly and snap some necks. I think Toyota deliberate softened the throttle response in the 4G to prevent that, and perhaps 100% throttle request is mapped to, say, 60% throttle opening in 4LO.

However, the 4G is very capable of building turbo boost right off idle RPM. If you are suggesting that the engine is physically incapable of building boost at partial throttle, that is not supported by observations in 4HI.

 

Id imagine toyota tries to limit torque output to keep the drive train together while they're under warranty. Some cucklefuck somewhere will try to launch/yank in 4lo and turn it into an external combustion engine in the process. Or reshape the cab/bed floor with driveshafts.

 

I can't find anything official in any tech docs but if you punch it in to google you get this, makes sense they would want to limit torque to protect the driveline in 4L as your essentially multiplying available torque to the driveline by 2.5 in 4L.
Easiest way to limit torque on a turbo engine is to open the wastegate and dump the boost.

 

It's definitely wastegate on these trucks. Other trucks won't allow the throttle to fully open in 1st. There's lots people don't know about.