Relationship between MAF scaling and load on AT

[BishamontenZC6]

Hi,

Here's a question, as I'm trying to understand how my '14 AT BRZ responds to OTS tunes, before probably switching to a tailor made solution.

As mentioned in a previous post, for the past months I've been going back and forth between 2 versions of Wayne's V168 lean 2% tunes : the one for E5-10 gas and the one for E0-5. The only difference between those 2 tunes is the MAF scaling. For the context, in my country, gas is supposed to be ethanol free.

Here's what comes out of it :

E0-5 : Car drives well, engine and throttle feels full and strong on CL (close to stock feeling), OL and WOT feels nice but not as potent as the E5-10 tune. AT's auto mode shifts and reacts well and mostly spot on. On datalogs though, LTFT is high : around 6-9% when throttle is applied, and 13-18% at idle (creeps up over time). AFR at 6'500 WOT is 11.4.
Log : https://datazap.me/u/ginkei/lean-2-e...log=1&data=1-8

E5-10 : Car drives well but engine feels a little bit empty in CL (like it needs more throttle to get the same amount of power). AT's auto mode shifts are lazy and I get some rpm drops and slight hesitation between shifts at mid throttle acceleration. It upshifts very early and won't downshift as reactively when needed. OL and WOT feel great and push nicely, with deep noise. On datalogs, I get a nice 11.7 AFR at 6'500 WOT and LTFT in CL is constantly between 0-4%, with stable 4.6% at idle.
Log : https://datazap.me/u/ginkei/wayne-le...log=1&data=1-8

Because of the high idle LTFT on E0-5 tune, for peace of mind I took some time to check for vacuum leaks, etc, and there's nothing. The fact that the E5-10 tune has a stable and "normal" LTFT at idle tends to confirm that it's correct.
Concerning the transmission, ATF has been changed 40'000km ago (car is 127'000km) so I don't think the hesitation between shifts comes from a worn out fluid.

So here it is. How come the transmission reacts better with a tune that obviously has an off MAF scaling ? And why a tune that's made for E5-10 gas works better on my car with gas that's ethanol free.

[tomm.brz]

Because lower maf = lower engine load = more timing usually

I don t get it why you want to force urself to stricly use OTS maps, they are made-up tunes that are created with the intent of using them in Any car, of course they aren t perfect.. no car or sensor is the same there is always some variance

If you fine tune the maf and maximize timings (a k a doing a Real retune, you can even start from ur current tune if you want) you ll get no strange ltft, no waiting time for trims to get learn ed, consistent full throttle pulls and performance

OTS tunes are just good starting point to me, actually i consider them pretty useless as they try to make a better job than the stock tune, but retain all the defects... it s a poor way to tune your personal car

[BishamontenZC6]

Tomm, as I said before I've always been aware of the limitations of the OTS tunes and I will most probably move to a tailor made one, as we discussed.

In the meantime I'm stuck with OTS because I don't have the time to do the necessary datalogs for the custom at the moment. So I'm taking that as an occasion to understand how all of this works technically, with the added complication of my BRZ being an AT.

My concern isn't so much power at WOT as I rarely do it in everyday driving (even though I appreciate having it when I do), but mostly about mid range torque and having something that drives well and smoothly in CL and doesn't feel sluggish or needs to really push the gas pedal to actually move like it's the case with the OTS tune that apparently has the most correct MAF scaling for my car, based on LTFT numbers.

So here's the deal : would a custom tune be able to retain the strong and smooth feeling in CL, with mid range torque, plus strong pull at WOT ? Or would it be all the power in WOT and nothing under ?

[Dzmitry]

Originally Posted by BishamontenZC6

Tomm, as I said before I've always been aware of the limitations of the OTS tunes and I will most probably move to a tailor made one, as we discussed.

In the meantime I'm stuck with OTS because I don't have the time to do the necessary datalogs for the custom at the moment. So I'm taking that as an occasion to understand how all of this works technically, with the added complication of my BRZ being an AT.

My concern isn't so much power at WOT as I rarely do it in everyday driving (even though I appreciate having it when I do), but mostly about mid range torque and having something that drives well and smoothly in CL and doesn't feel sluggish or needs to really push the gas pedal to actually move like it's the case with the OTS tune that apparently has the most correct MAF scaling for my car, based on LTFT numbers.

So here's the deal : would a custom tune be able to retain the strong and smooth feeling in CL, with mid range torque, plus strong pull at WOT ? Or would it be all the power in WOT and nothing under ?

Custom tune should do it all, if done correctly, yes.