chris72 wrote:I remember reading an old fuel injection article where GM experemented with injection timing and found timing had little effect on the engine as the fues simply collected behind the inlet valve. However that would be for 1980's low reving v8 engines. with todays better injectors you would loose the benefit of better fuel atomisation.
Can anyone tell me if the injector offset value is before or after the ignition event for the injector ? if so would using this be of benifit in this application ?
Injection timing becomes more important when you have large injectors, as well as large quantities of fuel to inject. With a large injector, your pulsewidth is shorter, so it's more important to time the injection event as it relates to the induction event. With larger quantities of fuel, it's critical that you time the injection so that you can avoid fuel puddling (in some instances, not all) and more importantly, gain the most from the cooling effect of the fuel. I've seen some impressive results on high specific output engines (around 600hp per liter) where nothing was changed except the injection timing. As with anything, the results of a change are often more dramatic at higher power levels.
What's worth noting is that many OEM ECUs will alter between open and closed-valve injection (meaning fuel is injected when the inlet valve is closed or open) depending on operating conditions. At full load, most will tend toward open-valve injection, but at low load they'll use the hot intake valve to assist in vaporizing the fuel, so they'll use closed-valve injection. On cold starts with low load, they'll switch to open-valve injection to reduce wall-wetting and fuel puddling.
I can't recall how the offset value is calculated, that would be useful to have indicated in the software. What I suggest is doing several pulls on the dyno at different injector offsets and monitoring the change in power output. Changes in the injector offset should result in a slight change in your wideband reading. In this instance I wouldn't use the wideband value as a reference for making changes so much as I would the power output to see what the engine responds well to.
i have found the information below from suzuki
