Modifying injector scaling and MAF curve...

[x99percent]

No, it is true of the stock ECU.

I have *never* seen this.

If you were to install STi pink injectors in an otherwise stock WRX, and use the injector scaling to compensate, you should notice NO change in timing... the MAF signal and scaling are unaffected, so the same load sites will be hit in the timing tables.

If you try to use injector scaling to compensate for a BigMAF for instance, your fuel table might be close but your timing is going to be off.

Now, it *is* true that a BigMAF alone will skew the timing, because the BigMAF skews the MAF signal! Injector scaling does not skew the MAF signal or g/s values.


This whole conversation was originally about fueling. I did make note of ignition timing at the bottom of my first post in this thread.


From my experience:
- Injector scaling does not affect ignition timing.
- Installing a BigMAF and/or adjusting the MAF table will affect ignition timing, because you're skewing the MAF signal.

Not trying to be a jerk... I'm just speaking from my personal experience.

[x99percent]

On top of that, if you choose to make large changes to the MAF table, you'll end up with something like this anyway:


So, you got resolution back by going to a BigMAF so that you don't max out the MAF sensor, but then you're going to purposely give up that resolution in the MAF table? Why? I used to hit 4.5V regularly on my old BigMAF...

Yes, I realize that if you do it my way, you'll have to rescale the timing maps... but at least then you still have full resolution. [shrug]

[Freon]

If you were to install STi pink injectors in an otherwise stock WRX, and use the injector scaling to compensate, you should notice NO change in timing... the MAF signal and scaling are unaffected, so the same load sites will be hit in the timing tables.

Absolutely correct. I don't believe I've said directly or inferred otherwise...

If you try to use injector scaling to compensate for a BigMAF for instance, your fuel table might be close but your timing is going to be off.

Now, it *is* true that a BigMAF alone will skew the timing, because the BigMAF skews the MAF signal! Injector scaling does not skew the MAF signal or g/s values.

I don't think you understood the context of what I wrote. You CAN use misuse injector scaling for the purpose of rough adjustment for a change in MAF diameter, you shouldn't do it, it WILL cause timing problems, among other things (load areas for CL/OL, anything that uses load). The effect is true on a stock ECU! The OP is about using a BigMAF, and that is the context of my post...

Now, the guys stuck on a 16bit ECU are going to have to do this. As per the above post, you lose resolution and hit your ~300g/s or whatever limitation due to the way the information is stored. I think the long term solution is to load up a new XML, shall we say, a special "Extended range" setup XML, modify the HEX CALID to a new standard (say, replace last two characters with "XL"), and have the XML do the necessary work for recalibrating everything. It's a lot of work, but I think it would be best, again, in the long term.

[rewt]

Hmm... a lot of good information in this thread. So, what do you both think would be my best option for proceeding?

Basically, I would like my car to run the injectors and BigMAF happily, so I can disable the UTEC's injector scaling. I guess you can say, I'm tired of lying to my car... not to mention, I think my car's stock ECU can handle the MAF/injector change better than the UTEC's scaling (IF I can map it appropriately).

[x99percent]

I don't think you understood the context of what I wrote. You CAN use misuse injector scaling for the purpose of rough adjustment for a change in MAF diameter, you shouldn't do it, it WILL cause timing problems, among other things (load areas for CL/OL, anything that uses load). The effect is true on a stock ECU! The OP is about using a BigMAF, and that is the context of my post...

That's just it... the timing problems are not caused by the injector scaling. The actual source of the problem is the change in MAF diameter. Trying to fix things by *only* adjusting injector scaling is attacking a symptom (fueling), not the real problem (load scaling).

Semantics. [shrug]