When does an injector "turn-on"

[99VetteVert]

How do I obtain the beta version mentioned 6/7/07?

Jim

[alanderson1978]

I would think you would want the injector to close just before the valve closes, just enough to make sure all the fuel makes it past the valve.

[eficalibrator]

In the OEM world, we almost always INJECT AGAINST A CLOSED VALVE to improve evaporation and reduce bore wash. The warm valve does a darn good job of evaporating fuel, given a little bit of time. If you actually look at a log of injection time vs crank angle and valve timing, you would see that at idle and part load, the injection is completed some amount of time prior to inlet valve opening. This time for evaporation gives better overal mixing when port velocity would be otherwise low, which in turn leads to better emissions and torque output.

The only time we don't really want this is if the engine exhibits "short circuiting" of the fuel where too much of the fuel vapor is drawn out the exhaust port due to high overlap or scavenging, leading to misfire.

GM uses units of reference crank pulses, knowing that a crank pulse is equal to a fixed number of degrees of rotation.

If you were to physically shift the phase of the crank target wheel, you would also mess up the relationship between the "gap", TDC#1, and camshaft target wheel step location. This has the potential to play games with lots of other critical diagnotics such as misfire, dwell, and camshaft synchronization.