Miata Turbo Forum - Boost cars, acquire cats. - VE definition? (cross-platform w/ AEM)

- ECUs and Tuning (https://www.miataturbo.net/ecus-tuning-54/)

- - VE definition? (cross-platform w/ AEM) (https://www.miataturbo.net/ecus-tuning-54/ve-definition-cross-platform-w-aem-72105/)

Quote:

Originally Posted by TurboTim (Post 999937)

I tried AEM's autotune, which uses a target AFR table to tune the PW map, and it made some scary changes within a few hundred feet so I turned it off, this was years ago. that too should work well if I took the time to learn how to set the various autotune control settings.

exactly, you adjust the autotune settigns to change more slowly.

Quote:

Originally Posted by JasonC SBB (Post 1000578)

RPM fuel trim is in Series 1.

ok then. I will look at it. But at the moment I can't think of a reason for a separate fuel trim due to rpm. That's kinda sorta the point of the fuel map. Especially cylinder specific. Maybe if one injector's dead time varies differently as rpms increase compared to the others to the point of warranting a trim. And who gets that info besides figuring it out on your own using the methods you described a while ago.

Quote:

Flat, as in all 100's, initially.

I choose uS per bit initially that gives me those 100's.
i.e. 100 x us/bit = fuel pulse width I need at 100 kPa.

boost comp curve crosses 0% correction at 100 kPa.

Ahh ok that makes more sense thanks. Slick. If the injector dead time curve/battery offset was accurate I'm sure your rows are fairly flat, less funky intake resonances or vtec and whatnot. Boost comp makes the columns flat. Tweak individual zones as needed with somewhat greater resolution. I.e. my bit values in the 100 kpa row are less than 100. I think.

Quote:

Originally Posted by TurboTim (Post 1000605)

ok then. I will look at it. But at the moment I can't think of a reason for a separate fuel trim due to rpm.

The VE vs RPM of the motor will be programmed into the RPM fuel trim. This also flattens the fuel table, and reduces the amount of tuning you need to do to it.

Terrible thread is terribizzle.

Think of being able to tune a 2D VE vs RPM table, and a 2D VE vs MAP table.

Most VE effects change with RPM or with MAP, but not both. After you tune both 2D tables, where will be little adjustment needed for the 3D fuel table, which starts out as completely flat.

Quote:

Originally Posted by TurboTim (Post 1000605)

BTW that's a poor way of trying to effect a dead-time change.

Quote:

Originally Posted by JasonC SBB (Post 1000702)

Think of being able to tune a 2D VE vs RPM table, and a 2D VE vs MAP table.

.

Yeah that makes good sense. I will try this. I know my 100kpa row is good so I can get a ms per bit starter value and the rpm trim curve from that row. The high vacuum rows are good too so I can calculate a bost comp slope that should be accurate enough for my 1:1 regulator.