Tuning a water injection?

[crustodd]

Hey Jeepers,
In an effort do help deal with some ping issues and perhaps gain some power and other benefits, I've just installed a CoolingMist VariCool II water/meth injection setup. I'm gonna' just try using water to start with. Here's my question(s). It reads a 0.0-5.0 volt input for a signal for N/A applications. You can use the TPS or MAP. I picked the TPS. If my stroker is idling at about 675 rpms, would that be about about a 0.5 volt reading as a starting point? If our stock rev limiters are set at 5200, would the halfway point of 3000 rpms (roughly, staring at 675 rpms) be giving a reading of 2.5 volts? Is the TPS function linear in that fashion? Is WOT an automatic 5.0 volt register? I can set the injection to come on at a minimum RPM/voltage, the RPMs/volts that it's at maximum, and what percentage of the max flow the injector is capable of. My stroker has been pinging more lately as it's be hotter weather, from about 1/4 to 1/3 throttle on. It was 90+ here today and the initial setup/rough tune seems to DEFINITELY be helping, so this is a step in the right direction. I'm currently running premium too and I hope to be able to tune back down to mid-grade or even regular fuel. Anyone have any experience with these units?

Thanks for your brains everyone,

T~

[crustodd]

WOW! NO responses? Well, I'm kinda gettin' the hang of how this thing tunes anyway. I scored some 65% meth/35% water from a locale manufacturer for $2.50 a gallon! NO more ping! It's a little stumbly at high rpms, but I think I may need a bit more plug gap. Definitely is more torquey around town. Runs a bit cooler too, even in 85 degree weather. Should keep the pistons,valves, etc... nice-n-clean.

[crustodd]

More updates,
Well, my stroker is now running quite a bit smoother from start up on (not quite sure why on that) and the ping is gone. The 65/35 meth/water blend sure smells interesting and after opening the plugs back up to .045, it's running pretty strong. Just a little stumbly around 4700 rpms and up, WOT. It seems to be running cooler too, even with the ambient air temp in the 90's, Any thoughts on the stumble at WOT and upper rpms? It feels almost like the rev limiter being engaged, but at too low of rpms.

T~

[hatem61]

Hi... Glad you are happy with the setup

Although, I am questioning the crowd's response

my 2 cents: TPS response should be linear ( throttle opening % vs volts )

Normal operating voltage 0.2 - 4.4 volts corresponding to 0-100% throttle.
Beyond those values the PCM will likely set a DTC.

[crustodd]

The way that the controller works, it allows you to set the min./max voltage that the injection functions at and then the LED give a reading of where the voltage is at as you drive. It seems to be around 0.5 at idle, 0.9 to about 1.5 at around town throttle positions, and only around 4.0+/- WOT. That seem a little low, doesn't it?

T~

[hatem61]

Nope... 0.5 - 4.4 volts range is just fine. There are some small differences between different cars, but your values seem fine.
I can try to see the actual vales on my vehicle.

[crustodd]

Hey All,
Another interesting development is I seem to have gone up a fair bit in MPG with the water/meth. I did about 190 mile road trip today, some at 75-85 mph and a few full throttle blasts and I'm still over half a tank . If these strokers make a good chunk of torque around 2700-2800 rpm, would the corresponding road speed produce better mileage than a slower speed where the engine was at a lower torque percentage? Does that make sense? Another interesting effect of the h2o injection seems to be that I'm getting in to overdrive quicker and the power band seems so much broader, that it stays in overdrive through a wider range of driving conditions. Unichipin' it on Monday. That should get it right to the knats whiskers.