GR Yaris Balance of tuning and durability limits

[p3.auto]

If it is a sensor issue, why the fix is updating the AWD ECU via the OBD? Wouldn’t make more sense to replace the actual sensor?

As the sensor hasn’t been superseded I would assume it’s down to how the ECU interprets the data from it. The TSB says the fix is a software update

 

[MRA3]

As the sensor hasn’t been superseded I would assume it’s down to how the ECU interprets the data from it. The TSB says the fix is a software update

That’s what I was wondering when I saw your comment. Makes sense…

 

[yuri1312]

The overheating clutch pack is actually a sensor issue, there's a technical bulletin out for early models to have the AWD controller updated which only happened a few days ago (if you weren't aware). Explains why some get the issue and others don't, it's not actually overheating. Mine's never had the issue but I think my build date is after Toyota made the changes.

Yep I'm aware of that fix (actually posted the pdf's above ) . I was referring to toyota acting to produce that fix based on input from multiple owners who were experiencing that. Still, pretty strange that they started applying the software fix to cars made after may 2021, and only now, more than 2 years later have finally released this as a recall.

 

[yuri1312]

Having had to account for stuff like this in the past I can easily imagine it’s something like the smoothing algorithm in the ECU not handling transient signals from the sensor very well, i.e. the ECU sees a number of ‘high’ readings in x timeframe and flags an over-temp warning, when in fact it was just a couple of spikes and the pack is not in fact overheated.

That, coupled with a natural variation in sensors not seen during development, could account for it, and explain why an update to the ECU to better tolerate the variability from a wider range of sensors would fix it.

yep, given it's a software fix, that would be my guess as well. they probably increased the analysis time window used to trigger the overheat condition, or reduced the sensor sampling rate that's effectivelly used by the AWD ECU, to avoid triggering it when momentary reading spikes occur.

 

[p3.auto]

Yep I'm aware of that fix (actually posted the pdf's above ) . I was referring to toyota acting to produce that fix based on input from multiple owners who were experiencing that. Still, pretty strange that they started applying the software fix to cars made after may 2021, and only now, more than 2 years later have finally released this as a recall.

My bad sorry, should have paid more attention

 

[p3.auto]

Oh I know, it’s just easier to talk in terms of peak power as most cars on standard turbos will have the same or similar power band. As you say it depends where peak torque is too. Can’t remember exactly but it’s about 400-450NM peak around 4500rpm.

The synchro issue is just a poor design, torque won’t kill them. Only solution is to slow down gear changes.

The detent spring issue again is a poor design, would happen to a standard car too.

The input shafts I agree will be more likely to fail due to increased torque but synchros and detent springs could happen to anyone

As for next steps I’ve gone with the Kotouc 7 speed sequential, just discussing ratios with them to best suit how I drive. Expensive but replacing gearboxes every 2 years is also expensive and I do like rally car noises

Huh, apparently I can't edit posts on here, didn't realise.

Just wanted to clear up that I spoke too soon, i've ordered the XShift box not the Kotouc. Went for the 12/51 gearing in the end, 7th is a little shorter than OEM 6th but the difference in fuel economy will only be about 2mpg with it running 400rpm or so higher at 110kph. Sticking the info in here until I make a proper post about it which I probably won't but maybe. Nothing like a time traveller coming back in 10 years wondering where one specific bit of info is to fix their car hahaha.

This info was kindly provided by XShift for comparison. Set to 7200rpm to calculate theoretical VMAX and rpm in 7th at cruising speeds. As you can see at 110kph (close enough to 70mph) the engine will be about 400rpm higher in 7th with the XShift but with my current aero setup I have so much drag at high speed I could use the shorter gears and just deal with the approx 15% penalty to fuel economy. when you're averaging about 18mpg anyway it doesn't really make much difference

VMAX will come down from a theoretical 286kph to 250kph but I can't remember the last time I went over 200kph anyway so that's fine. Again, with aero drag my 100-200 time is 16s which is worse than even a stock car, my gearing choice has been based purely on acceleration and in-gear punch.

OEM ratios -

7 speed 12/51 ratio -

Interestingly XShift also offer a transfer case modification to feed it via the gearbox oil pump as they say there is a risk of overheating oil in there leading to premature failure. I haven't taken this option for now but it's something that can be considered, they would need the transfer case shipped to them. I know Fensport killed theirs but they're on sticky tyres and a big turbo so I don't know how relevant this is yet to my needs.

Also decided to go full send and pick up a hybrid turbo from a company i'm working with (isn't on the market yet) and the usual Kelford 267A's and 1100cc injectors/fuel pump. If Acme need to map in the flat foot shifting they may as well map in a new turbo while they're there

 

[Onehp]

A: Might as well do the
B: YES OF COURSE ALWAYS
A: I didn't say what and you don't let me fi
B: YES

Anything else you forgot?

 

[p3.auto]

A: Might as well do the
B: YES OF COURSE ALWAYS
A: I didn't say what and you don't let me fi
B: YES

Anything else you forgot?

Technically Matteo put the idea in my head. Having a tuner who gets more excited than I do doesn't help