Rote8

I have hit 230% load, I have my fuel and timing set for the larger than normal load levels, but want to change it.....

If I scale my MAF calibration by 50% (cut it by half), can I then scale my fuel injector size also by half and get the same or near the same fuel trims?

I would then need to adjust timing and fuel to match the closer to 115% load from my current 230%?

Can someone tell me if I am on the right track?

Brettus

iTrader: (2)

No ..... That's not how you do it .

Have a read of this thread ............ (ignore all comments from Teamrx8)

https://www.rx8club.com/series-i-eng...erride-248857/

Harlan

iTrader: (3)

That should actually work, but as Brett pointed out there is an easier and more correct way.

Brettus

iTrader: (2)

Would be pretty dodgy IMO ....Can see several issues . Main one being the scaling the maf that way being a logarithmic curve and all ....

Brettus

iTrader: (2)

So you must be running 19psi ?

Rote8

No, but I have seen 18 PSI at 5500 rpm; I have a 2.1 liter blower, not the 1.7...



Again, I am not trying to make my tune work at the high load, it already works OK, but at the higher load readings
I want to get the calculated load back to around 100 percent, I think my ECU may learn trims better that way, instead of learning bad trims for the first few days after a reflash...

To my knowledge, scaling the MAF values and fuel injector size at the same time can make the calculated load reading go to what ever you desire, while staying close in the fuel trims if it is done right.

By scaling what my ECU perceives at the MAF and injectors sizing, I get the same power at a lower load reading.
This lower load reading means I need to scale my timing and fuel curves back to match the now lower load levels... (kinda chasing my tail)

My current tune reads a calculated load of 9 at idle, so I wonder if the idle load will scale to down to 4.5?

Or, should I just leave it as is, because it runs great after it finally learns for a day or so, even if my trims are fine.

Rote8

Exactly.

So, can it be successfully scaled against the injector size?

Do I have to do this the long way around; scale the injectors 50%, then completely redo the MAF calibration to the new injector size?

It's getting to the "don't F with it anymore" and just drive it, if I am not going to make the calc load 100% reading scale to my max engine output.....

Kinda thinking that as long as it drives good, not to worry about what load percentage the ECU reads, as long as timing and fuel are right at my 230% plus load. (or just don't go over 5500 rpm under full throttle...)

Brettus

iTrader: (2)

Sounds like you just need to scale the maf at idle/cruise to eliminate trims and you will be good !

The rest of your post made my brain hurt .... Don't feel like trying to work it out when it's not the right way to do it ......sorry .

slash128

I'm trying to understand why you would want to scale the load in half. I'm quite likely missing the obvious but I think your bigger problem is the 5V limit for the MAF. You can account for up to 800% load by simply maxing the IAT and Baro multipliers. Which you will find in the link posted by Brettus.

Side note auto wreck comedy: When I typed that last sentence I came out to be: Which you will find in the link posted by a fetus.

slash128

Also, to scale the MAF by half wouldn't you need to double the intake flow? Regardless of what the number is it still has to be be relative, no? And ditto on what Brettus said, it's not a linear scale...

logalinipoo

I've seen reference to what you're asking on subie forums before, but I'm with the rest of the guys, the calc max limiters work.

oh and congrats.

Rote8

The "actual" max load is a physical function of the engine, timing and fuel; regardless of the ECU calling max load 100%, or 400% that is still as much power as you get.


I want to scale back my MAF calibration, and compensate with injector size, so that both the MAF and injectors are lying the same way to the ECU.

This should balance out trims and make the ECU read a lower calc load when generating full power....

In a way, it's cosmetic where 230 percent load does not seem right, especially when I can still push it higher...

/yes, I will need to do my MAF calibration all over again once I change the injector size.

Brettus

iTrader: (2)

Can you tell us why you want to do it via this mickey mouse method rather than .....properly ?

Harlan

iTrader: (3)

You forgot charge density. We double the load by doubling the air pressure.

Rote8

The WOT MAF calibration should be interesting with 230% load at 5500 rpm so far......