R32 Gtr - Atessa Confusion During Skidpan

[Hornet2572]

G'day all,

I have been playing with my R32 GTR for a little over 12 months now, and am still relatively confused as to how the 4WD system works in the car. I have been competing in a wet skidpan motorkhana championship throughout the year, and during those events have been confused by how the system reacts versus how it is supposed to react.

It's simply a very wet skidpan scenario, lots of revs, lots of handbrake and clutch work. I have noticed though that if I throw the car around a cone in a 180 degree turn, when I step off the clutch the rear wheels hook up quite strongly and no power at all goes to the fronts. The car sort of hovers with the rear wheels screaming for probably a second to a second and a half, and then the fronts kick in, and I launch off across the concrete towards the next cone.

In a drift situation where I am feeding the power on, and sliding sideways around the obstacles, mostly the fronts engage and I get a nice smooth all-wheel drift. Sometimes though, the fronts will only kick in mid corner, or will cut-out mid corner. I don't get a warning light, or any error codes throughout the competition, and all the fluids / reservoirs seem good. If I grab the handbrake too quickly before the clutch is all the way in, I get a 4WD warning light on the dash, so I know that at least the light is working.

Is there any hard and fast rule or information about how the system should be working in those circumstances? I get a lot of people coming up to me and asking if I have disabled the system, or if I have a controller and have put most of the power to the rears. Granted, none of the people who ask me own Skylines, or know much about them, so they could just be assuming it's meant to be constant all wheel drive?

On a dry road, the system works great and I've never noticed it cutting in and out during normal or even "spirited" driving on dry surface.

Anyone got any similar experiences? Or can at least fill me in if this is how it should be working, or if it sounds like there's an issue?

Cheers.

Cliffs

Under load on wet skid pan during Motorkhana competition, front wheels engage randomly, and disengage randomly, causing me to spin out which makes me sad. Help.

[jiffo]

Do you remember what the torque gauge is doing?

It could give you an indicator.

If the gauge is working instantaneously but you're not feeling the fronts grip, then the fault would be mechanical but if the torque gauge isn't reacting, I'd guess electrical.

As an aside I check mine in a wet grassy paddock, haven't done wet bitumen. (haven't had a wet paddock for a while either)

Does slides, straight line clutch drops etc and it hooks up as I'd expect, instantly, gauge and front wheels all happy together.

[datsun_1600]

I found this article interesting:

http://www.autospeed.com/cms/article.html?&A=107753

The G sensor is pivotal to how the system reacts. Also it might be worth re-calibrating the G-sensor. You can see how I did it in my thread here: http://www.sau.com.au/forums/topic/356654-r32-gtr-g-sensor-fix/

Regards,

Jeff

[GTSBoy]

I'd say that using a fairly crude AWD system in a scenario it wasn't set up for will likely cause unexpected results. The GTR was intended to be a tarmac race car. The ATESSA was pretty much there o make it power the front wheels on a straight line launch and to transfer drive to the front under certain lateral G conditions. If that Autospeed article linked above is the one where JE swapped or rotated his G sensors, you can get a good idea of how basic the program in the computer is.

[blind_elk]

Being the first incarnation of ATTESSA, the version in the R32 was quite crude, and relatively slow to react (compared with the versions in R33, R34). So it's quite likely that your manouvres on the skidpan are happening so quickly that ATTESSA can't keep up, and may lag behind or just give up in despair.

[jiffo]

There's some pretty clever blokes working on the "G" sensor and their results are astounding.

Datsun_1600 would be one of those blokes and there are others on the GTROC forum.

Incredible that upgrading this sensor can have such a profound effect on a 25 year old chassis.

Sure the 32 was the first ATTESSA version but the 33 isn't too different, maintaining line pressure to the transfer case clutch packs in order to reduce their reaction time.

I do like the electronic upgrade.

[GTSBoy]

Fixing a faulty G sensor and improving the performance of the ATTESA system as a whole are not quite the same thing.

There have been a number of aftermarket ATTESA controllers done by various people for various purposes. The early Jap ones were pretty much teh same sort of thing that JE came up with - effectively signal benders. But it's not really the G sensor that needs to be modded so much as making the ATTESA computer faster and more thoroughly programmed to be able to control the output side of the system more appropriately. Vis ATTESA Pro and so on.

[MrStabby]

IMO the biggest problem with R32 ATTESSA is its tune, not the response speed. The ATTESSA ECU takes fore/aft accelerometer and slip signals to push power to the front (which works fine, as we see in straight line response) but then uses the lateral accelerometer signal to reduce the amount of power that goes to the front (this function is way overdone). The signal benders reduce the lateral accelerometer signal, so the ATTESSA ECU doesnt cut power so much.

$60 ebay signal bender transformed my 32.

The more work you've done on your suspension setup to reduce understeer, the more power you'll be able to send to the front. Nissan included the lateral accelerometer/power cut function as a way to stop power induced understeer.

[Hornet2572]

Do you remember what the torque gauge is doing?

It could give you an indicator.

If the gauge is working instantaneously but you're not feeling the fronts grip, then the fault would be mechanical but if the torque gauge isn't reacting, I'd guess electrical.

As an aside I check mine in a wet grassy paddock, haven't done wet bitumen. (haven't had a wet paddock for a while either)

Does slides, straight line clutch drops etc and it hooks up as I'd expect, instantly, gauge and front wheels all happy together.

The gauge is working when the wheels engage. If I complete a hook turn and step off the clutch, as the rear wheels spin up, the gauge does nothing, but then as the fronts kick in, the gauge then bounces up to the level it is seemingly providing. So I think the relationship between the wheels and the gauge is ok.

I found this article interesting:

http://www.autospeed.com/cms/article.html?&A=107753

The G sensor is pivotal to how the system reacts. Also it might be worth re-calibrating the G-sensor. You can see how I did it in my thread here: http://www.sau.com.au/forums/topic/356654-r32-gtr-g-sensor-fix/

Regards,

Jeff

Cheers Jeff, I'll have a read through the article and your thread. A re-cal might be worth doing, even if it doesn't 100% fix the issue.

I'd say that using a fairly crude AWD system in a scenario it wasn't set up for will likely cause unexpected results. The GTR was intended to be a tarmac race car. The ATESSA was pretty much there o make it power the front wheels on a straight line launch and to transfer drive to the front under certain lateral G conditions. If that Autospeed article linked above is the one where JE swapped or rotated his G sensors, you can get a good idea of how basic the program in the computer is.

Of course - Never have I expected the system to work flawlessly while chucking it around a wet skidpan, and I am under no illusion that it was designed for that purpose. But Tarmac race-cars sometimes raced in the rain, so surely the system would have had *some* of it's design characteristics aimed towards putting the power down on a wet surface.

Being the first incarnation of ATTESSA, the version in the R32 was quite crude, and relatively slow to react (compared with the versions in R33, R34). So it's quite likely that your manouvres on the skidpan are happening so quickly that ATTESSA can't keep up, and may lag behind or just give up in despair.

Hmm... I think the lag is definitely there, but was hoping that it was for a reason other than that it just simply can't keep up.

There's some pretty clever blokes working on the "G" sensor and their results are astounding.

Datsun_1600 would be one of those blokes and there are others on the GTROC forum.

Incredible that upgrading this sensor can have such a profound effect on a 25 year old chassis.

Sure the 32 was the first ATTESSA version but the 33 isn't too different, maintaining line pressure to the transfer case clutch packs in order to reduce their reaction time.

I do like the electronic upgrade.

I'll have a look over on GTROC and see what I can dig up. Cheers.

IMO the biggest problem with R32 ATTESSA is its tune, not the response speed. The ATTESSA ECU takes fore/aft accelerometer and slip signals to push power to the front (which works fine, as we see in straight line response) but then uses the lateral accelerometer signal to reduce the amount of power that goes to the front (this function is way overdone). The signal benders reduce the lateral accelerometer signal, so the ATTESSA ECU doesnt cut power so much.

$60 ebay signal bender transformed my 32.

The more work you've done on your suspension setup to reduce understeer, the more power you'll be able to send to the front. Nissan included the lateral accelerometer/power cut function as a way to stop power induced understeer.

Thanks mate, the signal bender sounds like something I should look into. If I do a G sensor re-call, and test it, and then if still no luck, have a look at one of these jobbies, hopefully I can get a solution. Do you remember which one you used? Brand? Description? I'll scan eBay and see what I can dig up.

Thanks for the responses - It was a relief to log in here and not just see a bunch of replies of "Your system is f**ked" etc... There's still hope! Lol.

I will have a bit of a read of the G-sensor stuff and the benders and see what the go is.

Cheers.

[tricstar]

Check out the "Full Race ETS pro"

Complete stand alone attessa computer and digital G sensor.

[RBN1]

Assuming ATTESSA is working fine - Get the transfer case modded by a place that knows what they're doing. Power transfer comes on sooner and harder. Difference is night and day. Best $ mod for handling i've ever done.

[KiwiRS4T]

Being an R32 I would have thought for skid pan you would just pull the awd fuse and run in 2wd

[Hornet2572]

It basically runs in 2wd most of the time I'm competing anyway, and that works well for certain maps/courses, but I'd love the AWD to work full-time just to see what difference it makes. It's a wet skid pan, so no major loading of the driveline, it would just be interesting to see how it changes things.