I need to some how translate the injector duties or any sensor relating to the injectors to a 0.5 volt scale. any ideas as im stumped.

Scott

 

The duty cycle is a measure of time in milliseconds that the injector is open , not a volt increase as the duty cycle goes up . I do not know any sensor that will relate to the duty cycle of the injector on the same ratio and 5 volt scale . Maybe someone smarter than us will chime in and help you .Good skill to you .

 

The duty cycle is the percentage of time that the injectors are ON. The signal to each injector will be a square wave which you should be able to average out with an RC circuit. Once averaged out, the duty cycle will be the average voltage divided by the injector drive voltage. This could be done with analog electronics but its much easier to find a friend who can program a small microcontroller for you.

 

the ecu has an (electrical) injector output that, i believe outputs the actual IDC %. i conclude this from looking at the datalogit power fc logs.... they read as IDC% rather than voltages. further supporting this theory, i pick this % up on my AVCR boost controller by jumping the wire.

scott, i was wondering if perhaps you are running too small a water/alcohol jet??

howard coleman

 

as has been said the injectors are pulsed on and off by the ecu allowing and disallowing ground to the injector. the voltage is always 12v but "on" time changes

as a seperate idea, can you use a map sensor voltage? would also increase as duty cycle went up

 

The electroincs idea sounds great. I will try nd look maore into it. If this could be performed like you mention it could open up a new can of worms.

Howard im still trying to find the best way to control the flow. The map sensor is the problem because it can only mimic what the boost is doing and not what the fuel is doing. eg...

lets say the car comes onto 0 vac (boost) 3800rpm @ 18%injdut using 7.9GPH of petrol
It hits full boost @ 1.04 (Bar) @ 3157rpm @ 36%injdut using 15gph of petrol.
Then @ 7000 ish rpm @ 1.04 (bar) @90 injdut using 39.6gph of petrol.

If i was to work my water injection ratio out from these figures i would have a problem. If i use the public domain figure of 10% water to fuel ratio ( which i dont ) then it would have to ramp from 0 water - 1.5 gph of water to keep the curve consistant to the boost/fuel. But from this point on wards as the fuel demand rises due to air flow at higher revs the demand for water would also ramp up but would not be able to (due to the map sensor info which would be saying full boost has been achieved) Using 10 % rule it would require 3.9 gph of water at high end. It would fall short of this target by 2.4 GPH. This means it would only recieve 5 % water at high end and 10% coming on to boost.

This is my issue and im stumped as to how to suitably fix it.

Scott