2007 4runner Atrac VS 2010 Land Rover Terrain Response test and quick comparo video

[CruzadoBlanco]

Not doubting your answers by any means... But where did you learn all this?

being an engineering student i got curious, so i started reading into every system on these newer toyotas, especially the ABS system since it seems so complex on the surface. i also started doing research for a SAS when i eventually blow the front end up in the future

 

[CruzadoBlanco]

OP, I appreciate the video. It's pretty obvious that the LR performed better in this situation than the T4R. However, I'm a bit confused, because I've seen videos referenced on this forum where the T4R handled similar hills to the one you were using for testing, and did a much better job than yours did. To be honest, your 4Runner pretty much behaved as though ATRAC was not working at all. I would have definitely expected better performance and I can see why you were disappointed.

I have no first hand knowledge, not yet having had the opportunity to take my '06 on a similarly difficult trail (have to wait for summer around here). I wonder, though, if not using 4Lo had more to do with it than you may have thought. I spent quite a bit of time investigating the FJ Cruiser before I bought the 4Runner, and I'm pretty sure I read in multiple places that the FJ ATRAC is much more aggressive in 4Lo than in 4Hi. That may be true of the 4Runner as well.

Just trying to correlate all of the different experiences I read about here. Still don't have a real clear picture.

the performance of the ATRAC system can be effected by many things. from worn brake parts, or glossed parts, to a obstructed or partially damaged tone ring or sensor. even having old brakefluid could affect it.

 

[JB.]

The term A-TRAC has not been used consistently across generations in Owners Manual and brochure literature. I always dread trying to manage the term in discussions and I often resort to descriptive terms like "brake pulsing" and "engine management" to avoid doing so.

The acronym A-TRAC appears nowhere in the 4th gen manuals 2003-2008. It does, however, appear in the quick reference guides for those years so we can safely assume that the references to Active Traction Contorol in the owners manual are references to A-TRAC. The use of the term Active Traction Contorol in those manuals, compared to just Traction Control, apparently only serves to distinguish 4wd from 2wd models.

The A-TRAC with it's own switch, introduced in the 2009 4th gen TE and continuing in the 5th gen, is a more aggressive, low speed form. Presumably, the brake pulsing that takes place in a 5th gen without the A-TRAC button pushed is the same thing as the 4th gen 03-08 A-TRAC but I don't know.

fromLRtoT4R,

Thanks for the video. The Land Rover is indeed impressive.

Btw, the brake pulsing seems get a little more aggressive in the 4th gen in low range so at some point you might want to check that out.

 

[CAN-03runner]

Thanks for running comparo testing.
How come you didn't run this in 4Low center locked?
　
Pretty confident A-trac needs the center locked to activate. Without it you have Trac. Locking the center also disables the VSC if you don't have a VSC disable button or hack/mod. Otherwise VSC and A-Trac fight each other.
　
And based on if you are in 4Hi or 4Lo center locked, the algorithm is different; 4Hi center locked has a priority on stability, 4Low center locked has a priority on driving through. Shifting into "L" also further changes how it functions. There is a Toyota University type of document on this some where that I’ll try to dig up again.
　
To give A-trac a fair shake you need to redo these tests in 4Low center locked and in "L" gear to test the full capability of A-trac otherwise you are not testing its ability to get through and unstuck. And you have what looks to now be the somewhat constant test bed to recreate the test. The terrains of our playgrounds look like they differ, but I'm in 4Low, center locked, "L" pretty much the whole time. Rock and mud of the north east.
　
It also needs constant stable rpm, of around 2000 rpm.
Also I might try a yaw rate and zero point calibration. The ECUs make use of these signals to function properly. If nothing else, doing a zero point has for me significantly increased its street driving. VSC kicks in at better times and more predictable. http://www.toyota-4runner.org/5th-gen-t4rs/71093-yaw-rate-acceleration-sensor-zero-point-calibration.html or you can get Techstream or get Toyota to perform this for you via software.

 

[dkyleb]

being an engineering student i got curious, so i started reading into every system on these newer toyotas, especially the ABS system since it seems so complex on the surface. i also started doing research for a SAS when i eventually blow the front end up in the future

Of course! Could you link me to some reading material? I, too, am very curious.

 

[CruzadoBlanco]

Of course! Could you link me to some reading material? I, too, am very curious.

ill see what i can dig up both on my computers and the internet that i read through. one good source for info about our ABS and stability systems and even just the 4wd electronics is RockSolidToys. its a forum and site specifically for SASs on the 120-150 chassis (03+ 4runner, 05+ tacoma, FJ cruiser). There is a ton of info over there. ill try to find my FSM, it has a ton of info if you know where to look and what systems were called over the years.

found some sources that got me started

https://www.tacomaworld.com/threads/a-trac-trac-auto-lsd-explained-easy-to-understand-i-hope.70551/

Understanding & Using ATRAC II+ - Toyota 120 Platforms Forum

http://www.toyota-4runner.org/4th-gen-t4rs/145163-07-4runner-how-does-speed-sensor-work.html

 

[CAN-03runner]

ill see what i can dig up both on my computers and the internet that i read through. one good source for info about our ABS and stability systems and even just the 4wd electronics is RockSolidToys. its a forum and site specifically for SASs on the 120-150 chassis (03+ 4runner, 05+ tacoma, FJ cruiser). There is a ton of info over there. ill try to find my FSM, it has a ton of info if you know where to look and what systems were called over the years.

found some sources that got me started

https://www.tacomaworld.com/threads/a-trac-trac-auto-lsd-explained-easy-to-understand-i-hope.70551/

Understanding & Using ATRAC II+ - Toyota 120 Platforms Forum

http://www.toyota-4runner.org/4th-gen-t4rs/145163-07-4runner-how-does-speed-sensor-work.html

That's it! Post 47

 

[CruzadoBlanco]

That's it! Post 47

knew it was in one of those threads some where

 

[Drunner97]

I actually prefer to have the center locker there and add the rear locker to it.. I believe the Trails do not have a locking center.. just the rear.. and it works well, but I like the idea of a manually 100% locking center diff.. something about it very comforting.. maybe the 09 Trails had the second gen Atrac systems??

All 4th gens have a center locking diff. It's the difference between AWD and 4WD in the 4th gen platform, especially with the V8 full time AWD (4hi). Trails were the only one that came with the rear locker I believe.

 

[AKmoney]

That's it! Post 47

We have a winner!

This is great information, thanks for sharing. Clearly there are differences in how ATRAC is programmed when comparing 4H to 4L. Perhaps OP could give that hill a rematch with the xfer case in 4L?

 

[capri_auto]

How steep was that hill? I went from an 04 D2 to an 08 T4R for the same reasons, but my old D2 would have laughed at that terrain in 4 hi.

 

[RonJR]

Going up a hill in 4hi is in no way "better" than going up in 4lo unless you need to go faster than about 30 mph, which is hardly the case here.

Toyota is a pretty conservative company, and as we all know, they spend a lot of time and effort to "protect" us from ourselves, sometimes frustrating us in the process. It does not surprise me that Toyota would optimize traction control for stability in high range at the expense of motive power, and reserve the high traction settings for low range. I've got no problem with that - it seems a sensible approach given their broad customer base. I use low range all the time when off-road anyway - I find it gives me much better vehicle control.

What is unfortunate is that the whole operation of ATRAC is explained so poorly in the owner's manual. There needs to be an addendum for real off-roaders that goes into the details of ATRAC and provides solid tips for optimizing performance under various conditions. They've put an incredible amount of off-road capability into these vehicles - why keep it such a secret.

 

[capri_auto]

Going up a hill in 4hi is in no way "better" than going up in 4lo unless you need to go faster than about 30 mph, which is hardly the case here.

Toyota is a pretty conservative company, and as we all know, they spend a lot of time and effort to "protect" us from ourselves, sometimes frustrating us in the process. It does not surprise me that Toyota would optimize traction control for stability in high range at the expense of motive power, and reserve the high traction settings for low range. I've got no problem with that - it seems a sensible approach given their broad customer base. I use low range all the time when off-road anyway - I find it gives me much better vehicle control.

What is unfortunate is that the whole operation of ATRAC is explained so poorly in the owner's manual. There needs to be an addendum for real off-roaders that goes into the details of ATRAC and provides solid tips for optimizing performance under various conditions. They've put an incredible amount of off-road capability into these vehicles - why keep it such a secret.

I know 4hi is not better than 4 low in that situation... like I said the D2 would have made it up in 4hi without issue. Still, I think reliability is a very important factor when choosing a truck (probably the most important)and the t4r is plenty capable for my needs these days. I've seen plenty of videos of stock 4th gen 4runners going up worse with no issue. A lot has to do with the driver. I just got my truck and cant wait to take it to the trails that I hit with the D2 to see how it compares.

 

[RonJR]

Yeah, I'm also looking forward to lifting the front 2", the rear 1", trying it out on some moderate trails this summer, and getting some first-hand knowledge. I'll report back around July

 

[AKmoney]

I know 4hi is not better than 4 low in that situation... like I said the D2 would have made it up in 4hi without issue. Still, I think reliability is a very important factor when choosing a truck (probably the most important)and the t4r is plenty capable for my needs these days. I've seen plenty of videos of stock 4th gen 4runners going up worse with no issue. A lot has to do with the driver. I just got my truck and cant wait to take it to the trails that I hit with the D2 to see how it compares.

Here you go, I've done the work for you.. Reposting this from the other thread.

2004 4Runner. 4LO, center diff locked, ATRAC visibly doing its thing.



2003 Disco 2. 4LO, no center diff lock (open), traction control. Note crazy wheelspin due to the open center diff.

 

[fromLRtoT4R]

OP, I appreciate the video. It's pretty obvious that the LR performed better in this situation than the T4R. However, I'm a bit confused, because I've seen videos referenced on this forum where the T4R handled similar hills to the one you were using for testing, and did a much better job than yours did. To be honest, your 4Runner pretty much behaved as though ATRAC was not working at all. I would have definitely expected better performance and I can see why you were disappointed.

I have no first hand knowledge, not yet having had the opportunity to take my '06 on a similarly difficult trail (have to wait for summer around here). I wonder, though, if not using 4Lo had more to do with it than you may have thought. I spent quite a bit of time investigating the FJ Cruiser before I bought the 4Runner, and I'm pretty sure I read in multiple places that the FJ ATRAC is much more aggressive in 4Lo than in 4Hi. That may be true of the 4Runner as well.

Just trying to correlate all of the different experiences I read about here. Still don't have a real clear picture.

Atrac was definitely working.. you can see in the different modes, the 4runner performed differently. I will be checking into the braking system again soon, but fluid is good and rear pads were just replaced

 

[fromLRtoT4R]

Thanks for running comparo testing.
How come you didn't run this in 4Low center locked?
　
Pretty confident A-trac needs the center locked to activate. Without it you have Trac. Locking the center also disables the VSC if you don't have a VSC disable button or hack/mod. Otherwise VSC and A-Trac fight each other.
　
And based on if you are in 4Hi or 4Lo center locked, the algorithm is different; 4Hi center locked has a priority on stability, 4Low center locked has a priority on driving through. Shifting into "L" also further changes how it functions. There is a Toyota University type of document on this some where that I’ll try to dig up again.
　
To give A-trac a fair shake you need to redo these tests in 4Low center locked and in "L" gear to test the full capability of A-trac otherwise you are not testing its ability to get through and unstuck. And you have what looks to now be the somewhat constant test bed to recreate the test. The terrains of our playgrounds look like they differ, but I'm in 4Low, center locked, "L" pretty much the whole time. Rock and mud of the north east.
　
It also needs constant stable rpm, of around 2000 rpm.
Also I might try a yaw rate and zero point calibration. The ECUs make use of these signals to function properly. If nothing else, doing a zero point has for me significantly increased its street driving. VSC kicks in at better times and more predictable. http://www.toyota-4runner.org/5th-gen-t4rs/71093-yaw-rate-acceleration-sensor-zero-point-calibration.html or you can get Techstream or get Toyota to perform this for you via software.

I did have the center locker and Atrac was on 100%. I did not run either of the vehicles in 4low to mostly to show the differences between the two systems going up against each other fairly, and also for the simple fact that this hill just wasn't steep enough for 4low. When I ran that hill in 4low, the result wasnt much different anyway.. I can try to find sometime to record that, but the LR didn't break a sweat going up in hi gear

 

[fromLRtoT4R]

We have a winner!

This is great information, thanks for sharing. Clearly there are differences in how ATRAC is programmed when comparing 4H to 4L. Perhaps OP could give that hill a rematch with the xfer case in 4L?

Yes I can.. I did not notice a huge difference from before, but I will try as soon as I have some time and try to record it.. I will try it different ways at different speeds with different throttle applications. I will also be going through my whole braking system soon.. Just to point out, the 4Runner will make it up that hill using nothing but Atrac, its just not very consistent and everything has to line up.. On that second hill where you only see the Land Rover, the 4Runner had Zero chance to make it up.. none whatsoever.. Not because Atrac doesn't try, it just fails.. There is a slight possibility that it could just be mine, and if I find something wrong with the braking system, I will report and retest.. (Unless someone from Toyota is reading this and wants do it for me free of charge

 

[fromLRtoT4R]

Here you go, I've done the work for you.. Reposting this from the other thread.

2004 4Runner. 4LO, center diff locked, ATRAC visibly doing its thing.



2003 Disco 2. 4LO, no center diff lock (open), traction control. Note crazy wheelspin due to the open center diff.

Guys, you do know that Atrac works in hi or low right?? You only need to lock the center for it to work.. When low is required for torque, I use it.. Maybe people are trying to explain that it works better in low?? Well I know that, but its not much better.. You just have more torque to work with, thats all

 

[fromLRtoT4R]

How steep was that hill? I went from an 04 D2 to an 08 T4R for the same reasons, but my old D2 would have laughed at that terrain in 4 hi.

It was not a particularly steep hill at all. It absolutely did not require 4low or at least should not have required 4low.. You can see in the video that the 4Runner did make it up in 4hi center locked rear open using only Atrac.. It just struggled, way too much for my comfort!


one more thing I noticed! Atrac seems to have a much better handle on things when you are climbing on rock or concrete rather than dirt.. dirt and ruts seem to confuse atrac much more