[Richard L]

I am not too concern about the function of the flow gauge but the effectiveness of it. If the system cannot deliver accurately base on boost or any other form of signal, monitoring the afr with UEGO is a waste of time.

Water/meth flow based on boost without RPM is a non-starter, you will get different rate being injected under different gears. Coupling with the non-linearity of the piump speed based system, the afr will be all over the place.

Hence using UEGO as a failsafe is a pointless excercise. I can give you a real world example if you want.

As regarding monitoring a gradual loss over time, this method of monitoring is only effective on an all-on/all-off system. You can only base your previous maximum reading to the current one. For a progressive system where injection rate is not maxed out at all time, how do you compare your previous flow reading at 1/2, 3/4 throttle or different boost level?