EFI Injection Timing

[LindaPeterson]

Anyone with EFI set up experiment with the injection timing? My megasquirt MS3Pro was set at 360° as default. This means the end of the squirt is at 360° from TDC, in other words, just as the intake valve is opening. My understanding is you want to spray the back side of the hot intake valve to improve atomization. Research suggests, as rpm goes up, you spray progressively sooner due to the increased speed of the air flow.

I did experiment with the settings and found I could "move" the AFR up and down with different values. I settled on 270° around idle when the AFR max'd out (all the fuel was burning).

Thoughts / comments???

Can anyone share the valve timing curve for 3.2 Carrera head?

[kjellr]

[Dr J]

If I understand you correctly, I believe you set it at the exact opposite of what you should. You want to change the timing so as to have the richest values (lowest AFR) then tweak the VE table by reducing the VE values until you get the original AFR.

If you use lambda feedback you adjust the timing so that the feedback is removing the max amount of fuel. Then adjust VE to cause the feedback to go near zero again.

Think of it this way. If you need to pull fuel, your engine is operating more efficiently.

[kjellr]

Agree, the table looks totally opposite of what it should. Table was made based on low rpm testing only, up to 1600 rpm and high rpm values estimated with interpolation.

According to what was written in beginning of this thread:

https://www.miataturbo.net/megasquirt-18/itt-injector-timing-table-tuning-84981/

1. Tune VE to perfection
2. Adjust injection timing until you see the richest AFR for that VE
3. Readjust VE

It is wrong?