Spray injection controller

Forum 2005-2010 (read only) Hardware Development
1

Hi! This is my first post to this forum. I have soldering, electronics basics and computer experience. I've searched around but need some help getting started.

I recently discovered Arduino thanks to a friend and I'm looking at using it to save me a bit of money and solve a problem with my Jeep engine.
My Jeep engine has a performance modification which results in a gain of horsepower, but it also has a problem with ridding excessive heat during very specific conditions.

The Jeep straight 6 engine was designed to run just around boiling point of water, my mods have caused it to overheat when it's under load, the RPM's are between 1,000 & 2,000 (approx) and I'm into the throttle by about 25-30%. I've swapped radiators and spark plugs to no avail. This is putting a serious dent in my vehicle usability, I need to solve it.

I think that Methanol/Water or just Water injection will solve my problem. It's sprayed into the intake and flashes to gas with a huge cooling effect. Further, I think I can develop an arduino board to work as an ECU for the spray system. Sometimes this is referred to as a '5th injector'.

Unfortunately I don't know where to start........

I would like to use three inputs to trigger the spray:

1 - Water temp sensor (0-5 volts variable)
2 - Distributor signal (12 volt frequency - this is the input to the ignition coil and pulses to trigger every spark event - 6 per RPM)
3 - Throttle position sensor (0-5 volt variable)

When the water temp reaches 220f (approx 4 volts)
and the RPM > 1,000
and the throttle is > 25% (approx 1 volt)

Then a 12 volt relay would be triggered, activating a pump which would spray water into the intake and cooling the engine.

The chemical/physical properties of water injection are not the issue here, only the design and function of the arduino setup.

So, my questions:
**How do I choose the parts to get started with this? **
Where can I find the info on the input and output type

Thanks for the help in this project! :sunglasses:

2

I don't think you need too many extra parts. For the water temp and throttle position sensors, you can just connect them right to an A/D port on the Arduino through a resistor (just to limit current in case voltages go outside the 0V-5V range).

The 12V distributor signal can be reduced to the 0V-5V range through a simple voltage divider (say, 10k/20k to get 4V) and that connected to a digital input pin. The pulseIn() function can then be used to estimate the pulse frequency.

To drive the 12V relay, a standard relay driver can be used. Some typical circuits:

http://ruggedcircuits.com/html/circuit__7.html

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Need a custom shield? Let us design and build one for you.

3

Thanks Rugged,

So I take it that there is a basic Arduino board?

Where can I obtain a description of the basic board and it's 'shields' (add on's?)

Is there a 12v frequency shield? As opposed to dropping the voltage to 4v for the distributor input?

Thanks for the response!

4

You have lots of choices :slight_smile:

Here's a list of some of the shields and other hardware:

http://www.arduino.cc/playground/Main/SimilarBoards

I haven't heard of a "12V frequency shield". Perhaps you can buy a prototyping shield (I know those exist) and solder on some of the components I suggested.

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The Quick Shield: breakout all 28 pins to quick-connect terminals

5

How do I go about choosing my base Arduino board?

Sorry for the NOOB questions!

and Thanks again for your help here.

6

How do I go about choosing my base Arduino board?

How do I choose my next car? :slight_smile: Cost, features, performance, expandability, hackability, etc. What is important to you?

If you just want to get started, the base Duemilanove (or newer Uno) is a good safe choice, and I'd be remiss if I didn't push our own GATOR board :wink:

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The Gadget Shield: accelerometer, RGB LED, IR transmit/receive, light sensor, potentiometers, pushbuttons

7

Well, this going to be under the hood of the car, so it requires a proper, ventilated box. It should probably have a heat sync. It would also be nice to have up to 5 output ports for LED status as well as the 12v relay output.

Feel free to PM me with info on your companys offering!