Water Injection Code Mentioned In Change Log

[Tjabo]

James,

Regarding your water injection comments, is this similar to what was in MS1/Extra, where a high speed valve could be driven at the same duty cycle as a fuel injector, or is this intended to be something different?

[jsmcortina]

What it is at the moment is: Pump control, valve control and safety input.

The system is activated above tps, map, mat and rpm set points and then turns on the pump (if required.)

The valve output is a duty cycle from a 4x8 table of map vs. rpm.

The valve can be a low frequency solenoid type with the same low frequency range as boost control or a fast valve that opens as often as the tacho output.

I also included a "safety input" so that for example if the tank level is too low then the system goes into shutdown mode.

All highly experimental.

James

[Tjabo]

That is awesome James, other than it seems like I maybe just spent a bunch of money on a water/methanol injection setup that isn't as good as this will be!



Anyway, this is really great, and I am excited to see what the possibilities are with a slower valve in place of the aquamist HSV. I have a standard solenoid setup with a progressive PWM pump drive in my kit, do you think it would be possible to drive the standard solenoid with this output, and then run my flow valve output back into one of the various available inputs? I don't have any output info from the flow valve right now, but I'll get it. I do know that I had to configure the controller to 270 pulses per liter to get my flow valve reading accurately with what I was actually outputting for water/meth.

I think that the more I see all of the insane stuff MS3 is going to be able to do, the more I understand the need for the MS3X board, and the extra DB-15 connector. There is just going to be a ton of stuff going on that the MS3 is going to be able to do. It's amazing.

This is looking GREAT!

Thad

[jsmcortina]

You could probably use one of the (new) shaft speed inputs to read that flow sensor.

James

[Tjabo]

What kind of a signal are those inputs looking for James? I should have a chance today to shoot out a question to Coolingmist where mine came from.

I was thinking though that with this code, we might be able to interest Aquamist (or maybe Coolingmist, but Aquamist is the gold standard in water injection as far as I'm concerned) to put together a MS3 specific setup with a pump, fittings, nozzle, flow valve, and maybe a solenoid of some sort (cheap, not the regular HSV-$$$$$). I'm fairly sure Coolingmist might do this if Aquamist wasn't interested, and for sure it would be cheaper.

Thad

[jsmcortina]

The Shaft Speed inputs need a 0-5V digitial input at the CPU.
So for a true shaft input you'd be wanting a hall sensor or a VR conditioner.

The VSS inputs can either use the same or take an analogue input and calculate the speed from that.

So, for your flow rate sender you need to find out what voltage it is putting out. A circuit similar to this one taken from the MS1/Extra manuals would probably work as the input.



The "safety input" on the water injection is presently designed that it needs an active input or the system goes into the same shutdown routine as the AFRsafety system. This might need a selection to act as either a "system safe" or a "system failed" input. My current logic was that a "safe" input will fail safe - if the wire falls off the sensor then the system will shutdown. A simple "fluid low" switch would be less robust - if the wire drops off, the Megasquirt doesn't know there's a problem and the exhaust is full of melted piston.
(This is also why MS2/Extra and MS3 use different nitrous wiring to MS1. With the MS1 scheme and a wiring fault it was possible to enable the nitrous and NOT retard the timing or add fuel.)

James