changing the injector timing of a gas engine.
this is a long story about injector timing o a gas motor , not ignition timing. but it starts out as a quest to change the ignition timing, read it all and things will tie together in the end.
so i was looking for a way to adjust the ignition timng on my my, a 96 dodge stratus with a 2.5 v6. i realised the dizzy has 2 holes for mounting bolts, and that if i slotted these bolt holes then i could turn the dizzy and adjust the timing. so i pulled the dizzy off, mount it in my cnc and slot the holes. i didnt really know how to make any timing marks, so i just figured i would use a timing strobe light on cylinder 1's plug wure to gauge before and after timing in relationship to the tdc mark on the engine block. i put the dizzy back in and started moving it back and fourth while looking at the timing marks. what do i know the timing isnt changing!
after some internet research, it turns out the ignition on this car is timed via the crankshaft sensor, not the hall effect sensor in the dizzy. the hall effect in the dizzy is responsible for telling the computer which cylinder is at tdc, btc in relationship to the crank. the dizzy hall effect is also responsible for controlling when the fuel injectors open! yay so i realised that i now have the ability to adjust my injector timing. not the duration, but just the timing at which they injectors open in relationship to the crank. after more internet digging i found out that my fuel injection is designed to start the injector cycle when the intake valves are still closed and the piston is at bottom dead centre on the end of the exhaust stroke. and under light throttle such as cruising, the eitire injector event happens with the intake valve still closed. only when under any significant load does the injector duty cycle raise enough to start at bdc and stop someehere on the intake stroke when the intake valve is still open.
now, being not an expert on fuel injection, i dont have any reason now to like this. but it just seems to me that for max fuel economy, the injectors should start injection right as the intake valve opens. am i completely stupid in thinking this? i believe i should adjust the injectors to open right as the intake valves are opening. so i now have the ability to control when the injectors open by advancing or retarding the hall effect sensor in the dizzy. where do you guys believe i should place my injector timing efent at?
by the way my crank position sensor isnt adjustable. its positioned on the bellhousing and runs off of notches on the flex plate. theres no way to mod it to control ignition timing. but i have another method for that....