From My experience:-
One of the most obvious signs of incorrect injection timing on a petrol (gas) ice engine is not being able to achieve good stable AFR values at idle.
Its always a good idea to map out your intake camshaft lobe openning and closing. Then overlay your injection start point. If you are starting to inject fuel onto a closed intake valve, the atimised fuel will puddle on the head of the valve and get drawn into cylinder making it much harder to ignite. Injected fuel must take place when the intake valve is open. So we have some questions that comes to mind:-
1) At what point (time / degrees ATDC) after the intake valve opens do I start injecting?
2) How do I adjust it the injection timing?
3) How do I know when I've hit the sweat spot for optimum injection timing to achieve maximum efficiency?
The answer to questions 1 & 2... can be adjusted in the config of an after market ECU. Question 3 can only be anwered by careful torque measurements on the dyno.
As an estimate only, injection could start about 20+ degrees after the intake valve starts openning.
Ah.. what would I know!
