Interesting info on B3702 Injection timing

[Goldfinger911]

Hi Joe

I believe the injector timing is in crank regress and relative to TDC on the compression stroke?

Foe example on the LS2 the advance is 490 degrees when cold and 220 degrees at normal running temps, so the timing events for the LS2 are as follows:


Engine cold

Inj fires. 130 BTDC. CLOSED INLET VALVE
IVO. 16 ATDC
ICL. 118 ATDC
IVC. 40 ABDC


Engine hot

IVO. 16 ATDC
ICL. 118 ATDC
Inj fires. 140 ATDC. INLET VALVE BEGGINING TO CLOSE
IVC. 40 ABDC

The injector firing event of #1 cylinder is based off the crank trigger at TDC on #1. Also known as tooth #0 (on a 48 tooth crank trigger; 7.5 deg per tooth).

I have been playing with "a brand-x stand-alone EMS" on my LS1 and you can set the ignition and injector firing events of each cylinder by degree or tooth. More importantly you can see exactly when the injector is firing in both ways as well.

The reason I bring this up is I was amazed to see how a slight movement of the injector firing event affects idle, AFR, idle load, and throttle response. You also immediately notice things like, your AFR getting leaner on the gauge, but the exhaust smelling like unburnt fuel. So far, adjusting the event so as to yield the richest idle mixture (the most burnt fuel at a fixed pulse width) seems to get me closest to optimal with everything else.