[PuntoRex]

Do you mean looking at the signal voltage of MAF when the pre-turbo injection is on?

I had some experiences but no exact numbers as evidence.

I used to trigger pre-turbo injection by MAF signal voltage, i.e., when it exceeds the pre-set voltage, a comparator drives a solenoid to guide the water flow to the pre-turbo nozzle.

So, it should be triggered by a specific air flow rate, given that the MAF signal voltage can be mapped to it. I remember my setting point was around 4.2V, and the relative conditions were full boost at about 5000rpm.

However, at the time I noticed the trigger point was drifting by the ambience temp. When the temp dropped, the trigger point could drop to about 4500rpm or even earlier. It makes perfect sense because the cold air is denser, so the engine/compressor can suck in more air mass at less rpm.


Logging the MAF signal to judge the pre-turbo injection performance should be feasible, given that the ambience (inlet) temp should also be recorded.