Why use Gair

[TTC]

Ive read tons of posts where people use the non linear mat correction to make gair 100% which basically turns it off. Why would I want it on?

My situation:

turbo race car, gets hot generally tuned on safer AFRS, the last thing i want is gair to pull fuel as IAT gets hot. Never winter driven, for the most part sees only 15degC. Should i just leave it off? A little extra fuel isn't a bad thing since I don't care about fuel economy.

[TTC]

Ive read tons of posts where people use the non linear mat correction to make gair 100% which basically turns it off. Why would I want it on?

My situation:

turbo race car, gets hot generally tuned on safer AFRS, the last thing i want is gair to pull fuel as IAT gets hot. Never winter driven, for the most part sees only 15degC. Should i just leave it off? A little extra fuel isn't a bad thing since I don't care about fuel economy.

Perhaps leave it to add fuel when it gets cold out and nullify it when AITS get hot? Thanks!

[jsmcortina]

Air density is a key physical part of the speed-density equation. You can't "decide" that air won't change density, just like you can't turn off gravity because you feel like it.

James

[TTC]

I understand we can't cancel out the effect. But doesn't gair remove fuel when the Aits rise? Did i miss something? For instance when gair says 95% its 5% l eaner no? So by using the non linear table to make it 100% doesnt that sort of "cancel it out".

[jsmcortina]

Hotter air is less dense, so you need less fuel to maintain the same AFR.

James

[TTC]

OOO. So the reason its pulling air is because if it didnt it wouldnt maintain the afr I want. So as it gets hotter my tune will richen, so GAIR takes fuel out to compensate I think what I will do is ill use the MAT correction table make gair 100% and tune the car for the temps that day. I would rathter it not compensate and be rich for track days than have it pull fuel to maintain 11.5 afr for instance. If it goes to 11.3 thats not a bad thing really.

This make sense?


http://www.miataturbo.net/megasquirt-18 ... ble-57663/
where im getting some info.

EDIT: second thought. Wouldnt it make sense to let gair do its thing and adjust the VE table as im on the dyno. That way afterwards I can just tweak the gair and mat table to compensate if I feel its taking out to much fuel. so leave the non linear table at 0 0 0 0 0 0 ect and tweak it afterwards? To add a bit of fuel if I like?

On the other hand if i cancel out the gair correction I will end up with a VE table thats just a bit rich when its hot, but relativly fine with its cool? Is gair there to make the VE table vs AFR readings more or less consistent over the different ait readings, so therefore leave it in when VE tuning?

Or maybe reduce its authority to 50% ? I duno first time at dyno tommorow I want to be as informed as I can be. Should i just leave it as is? when doing my fine VE table tuning on dyno, or cancel it out so to speak and tweak it on the road later.

I have never touched GAIR in the 6 years of using ms lol.

[jsmcortina]

Go with your 'on second thoughts' ideas. I've found 50% scaling to be a good start, then use the non linear correction.

James

[TTC]

Thanks James.