Yesterday before dropping off the car we went for a little drive where I was able to use some full throttle applications and change through the gears a bit. I didn’t get to go full on through the corners mainly because of the gearbox in the boot but it was enough to get a feel for the car and the car felt strong again and thankfully didn’t seem to miss fire. As with my last post I am a little hesitant but it seems like it has been fixed.
What we did was to raise the fuel pressure via the Sard regulator and then retune the car, the reason we raised the fuel pressure was because the injector duty cycle on the ID1000’s were sometimes peaking at 97% on the track.
When you get above about 85% it meant the injectors were not linear in their control and the thought was it was dumping to much fuel into the car causing the miss fire. This was particularly the case on gear changes hence the reluctance for it to do it on the dyno.
It is the same with all injectors and you can see on this graph what I mean, right at the end of the graph you can see the curve change from a linear rising amount and it flattens out.
What happens is when the car is tuned if you can imagine you have a linear base for the fuel as you tune and then right when the engine is at peak power or rev’s that linear base changes and you have trouble picking where and when it is changing. This is the reason people always say that you should not run your injectors over a certain percentage duty cycle as it can cause leaning out or in my case cause over fuelling (probably the better of the two)
Voltage also has a big effect on the injectors so it is critical that you get a good amount of power to them.
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