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water injection flow sensor reading

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8psi boost pressure switch activates the water injection pump then right before the water injection outlet nozzle (that's placed after the IAT sensor so I'm looking at the water as fuel instead of only lowering intake temps because it does a bit more than that), I placed this in-line flow sensor that communicates to the ECU to activate the more aggressive timing and fuel maps (via an ADC breakout box).

Andre pointed out this solution to me a while back on the old forum and I'm finally getting close to running the car so...

what I need to determine is (before just seeing what happens on the dyno lol): the output voltage starting point and ending point...is there anything that says the signal on hall sensors like this start at 5v then lowers to 0v with more input from the water flow (like an O2 sensor) or will it start at 0v and go up to 5v with more flow input?

For my trigger activation voltage setting that switches to the aggressive maps: I plan to trigger the maps with almost any input seen by the sensor so do I activate the map switching at say 0.2v then deactivate at 0.1v or activate at 4.8v and deactivate at 4.9v? From my understanding, this isn't just an on/off switch sensor and though some more searching may turn up that kind of sensor, this one seems fine for the specs of DevilsOwn kit I'm running.

Yes, I will tune the fuel-only maps fully first, but the reduced cylinder temps and therefore lower pressures will allow me to run a bit more timing, a little less fuel and maybe more boost, but only when this sensor activates these maps because the water is actually flowing and if not, then I'm still running the safe amounts for fuel-only. So it's pretty close to a fool-proof water (and meth if you really want it) injection system...if it works lol.

here's the link to the sensor...maybe there's some info there that answers my question that I'm not picking up on...or i just need to dig a bit deeper:


I haven't had any experience with a water flow meter but my immediate thought would be to log the sensor output with your system active and see what sort of voltage you are getting out of it when your system is injecting as expected. You can then base your trigger points off this information. Let's say for example that with 3 litre/min flow the output is 3.5 volts. You could then trigger the system at 3 volts and know that you are safe. If you triggered the system at 0.1 volts, you could still be well off your target flow and the system would still swap to a more aggressive timing map and hence make the water flow meter somewhat redundant.

I'd personally log the output from this sensor as well so that you can monitor the injection performance over time.

makes perfect sense...just log a not-so-dry run then I'll know the full performance of the system...sooner or later, all this studying will become second nature once I actually get some of that real world tuning experience with these things. thanks again

Hi Tom

Interested to see if you had any luck with the water flow sensor ?



Actually I'll have some content to add to this shortly as we are about to install an AEM water/meth injection system on our Toyota 86. We also got the optional failsafe kit which includes a flow meter. While our initial installation will be using all of the AEM hardware, I've also witten a control strategy in M1 Build to directly control the injection via the Motec ECU.

I haven't gotten too far into it yet but it appears that the flow meter is a digital sensor that produces a frequency relative to flow. I'll know more once I get a scope on the output to see what's going on.

Good stuff Andre. Looking forward to seeing your results.

Are you planning on doing a webinar on Water Injection ?

It is a very under appreciated form of combustion control which can allow significant increases in power without the many disadvantages that come with changing to race orientated fuels.

Sorry, I must have changed a setting somewhere and didn't receive an alert of your comments, but I had a couple set backs in conjunction with other things outside of the project coming up and I'm just now getting back into it so I haven't actually been able to run the car with it yet. I will be sure to report back once I do, but that'll likely be a ways out unfortunately. I hate sounding like that guy with the painfully slow progress on an overblown project, but it is exactly what I have become...without the overblown part, just pain.

Hi Andre

Have you started using the aem flow sensor.

Im interested to see what flow range the sensor reads which I beleive may be 0-1000cc / min.

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