Progress update.....

No further on the kill switch. So I decided to finish the MPGuino instead:



That's right. the MPGuino is in the cluster itself.

Whee!

Here's how I did it.

There's only one spot this will fit in the cluster, slightly left of center. I didn't get a before shot, but you can see that this was all unused space. I hacked away until it fit:



As you can see, I had to cut away the bottom of the cluster to get it to align right. I also had to cut the overlay piece:


And the MPGuino fits like so:


Notice there are no buttons. Wouldn't be much good inside the cluster, would they? More on that in a bit.

I cut the black strip to fit:


And put the top back on:


Looks pretty good! Notice I filed the speedo down a little to improve the fit.

And plugged back in:


As I said, buttons have to be rerouted. There was a nice perforated section to break the buttons off, but it didn't break off so well......so custom buttons are coming soon, till then I'll just live with Big instant MPG screen.

Next project is an ignition kill switch.

I have a biased rocker switch installed in the empty defroster switch slot, not sure if I will keep it there after I try it out.

Hooked up a regular relay, only to find I had to hold the button down to keep the car running....oops. Need a double throw 'Bosch type' relay, so one of the contacts will be normally closed. So I have to decide whether its better to try and find one at a junkyard, and hope that it works, or buy one new for $10 at Autozone, hard to tell if they normally stock it or not. Anyhoo...

After reading on Ecomodder, it seems that the fuse method seen here interrupts everything, and so its best to just cut the injector wire. One member advocates using the cam position sensor, the wire coming off the distributor. I think I'll stick with the injector wire, but I'm curious to know if anyone here has used the sensor method, and what the advantages would be.

WARNING: LONG POST

What I know about the MPGuino:

I have wanted to build one of these since I first saw them. DIY anything is fascinating to me, especially where I haven't had much experience (electronics). So I started looking around.

First thing I found was that information on this is scattered and mostly obsolete. This device has gone through so many incarnations that it you have to read carefully to see if a problem applies to you or not. I did unearth the following - remember, total novice here:

~MPGuino is based on the Arduino platform. That's sort of like saying that it's built out of LEGOs or an Erector set. Arduino makes several prototyping boards, these have all the basic stuff integrated into a board; ATmega microchip, power supply, USB connector, timing clock, etc. They also wrote a language for programming these boards. So you could actually take one of these boards and write the MPGuino code on it, and hook up the components, and it would function properly. But that's not what you want to do.....

~After initial development on a breadboard, the MPGuino needed a circuit board. Fundamental Logic had been making the Iduino, a full up Arduino with a small footprint. This was eventually customized for MPGuino, bundled with components and sold as kits. DIY boards are still seen (JBD made some), and you see variations on the size and arrangement.

~Fundamental Logic is out of business.....  but the kits are still around second-hand. I got one of these....

~MPGuinos are available prebuilt for $50 from the code's main author, DCB.

~DCB is the genius at Ecomodder who wrote the code for MPGuino. He began by using Arduino stuff, perfected the code there, and has since moved on to other platforms, meaning we DON'T want the latest version of the code, just the last Arduino version (v0.75) Earlier versions have glitches. The Fundamental Logic kits shipped preprogrammed with v0.73, so they need updating.

~Since the FL kit was based on the Iduino, it retains the ability to program chips. You could put any ATmega chip in there, program it, and put it in another device. I plan to do this.

~The assembly directions on the FL site are excellent. Some have questioned their accuracy, they are 100% correct.

~Hookup to the car is a major headache. You are trying to find four wires - power, ground, speed signal, and injector signal. These are all at the ECM. I quote Mwebb:

Quote:

 

on my 1996 G10 ( 3 cylinder ) with 5speed

connector C1 pin 14 color white = KAM Keep Alive Memory , 12 volts positive , unswitched , always on
connector C1 pin 12 color yellow / black = Injector control / signal (on my car is yellow)
connector C3 pin 11 color yellow / green = VSS , Vehicle Speed Sensor signal (on my car is green)
connector C1 pin 1 color black / green = ground / negative

other year metros may not be the same
automatic transmission metros may not be the same
G13 (4 cylinder ) metros may not be the same
====================================
there are wiring diagrams in this forum , the Description / NAMES of the pins to be connected to do not change

~1996 does not equal 1995. Find the correct wiring diagram BEFORE you start stripping wires.... 

~All the signals are present at the ECU, disregard naysayers who like to run wires into the engine bay. If they weren't present, the engine wouldn't run. Don't believe me? Try starting the car without the connectors plugged in..... 

~The hookup is made via 4 conductor telephone cable, used for two-line telephones. Most cables I came across had only two conductors connected, for one line phones.

~The colors for telephone cable are NOT symmetrical. Looking at one end, assume #2 has 12v power.

12v
. . |
R B Y G
| . | . | . |
. . | |
. . | |
. . | | . . 
| . | . | . |
R B Y G
. . |
12v

Make sense? Now flip it 180deg.

12v
. . |
G Y B R
| . | . | . |
. . | |
. . | |
. . | | . . 
| . | . | . |
G Y B R
. . |
12v

Uh-oh, the colors are reversed. Bottom line? If you just wire the junction box as directed, it works either way. What a headache!

~Soldering the wire taps by the ECU is a good idea, to eliminate loose wires as a possibility.

~If the MPGuino reboots constantly, it could possibly be the software, not faulty wiring. After I upgraded to v0.75, it works fine. I'm still glad I soldered the wires, for peace of mind.

~After a big spark, check the fuses before assuming the wiring is bad.


It does work quite well, I am completely satisfied. I have not made the enclosure yet. (Enclosure is a fancy word for "box"...)

Hope this post helps somebody out there. I wish I could have read it when I started.

It's here.  The MPGuino, that is. I ordered an old Spiffie kit from a member on Ecomodder, and it arrived yesterday. I just got a chance to look at it. Here are the bits and pieces:





I read the directions closely.....

1 LCD - not included. [Was used by P.O. for project.] - I have one coming separately.
1 Atmega 168 chip, check. [He actually sent two!]
1 Surface mount phone jack, check.
2 5.1v Zener Diodes, check.
2 1n4004 diodes, check.
1 10K resistor, check.
1 220 resistor, check.
2 1K resistors, check.
2 100K resistors, check.
1 7805 voltage regulator, check.
1 28 pin socket, check.
1 16Mhz crystal, check.
2 18pf ceramic capacitors, check.
1 2n3906 transistor, check.
3 6mm buttons, check.
1 470uF electrolytic capacitor, check.

4, 0.1uF ceramic capacitors, uhhh.............not here? 

Great. So I can't put this together today, after all.

So I need some ceramic capacitors. Of course, I could go to Radio Shack and probably just buy them. But that would be waay too simple (and expensive). For not much more, I can probably build another MPGuino, which I'd like to do anyway.

So I looked around online, found a decent site, Tayda Electronics. They don't have everything, but they do have an awful lot of components. And everything is dirt cheap. Most of the stuff in my cart costs a penny each.

One little caveat is that orders are a minimum of $5.00. My order total is 1.24 so far....  That's for the missing caps, plus one of everything listed except the Atmega and LCD. Odd problem to have.....What else do I need from them?

I poked around some more, and they actually have the Atmega chips! Out of stock. So I emailed them to ask if they will let me know when the chip is back in stock. I will then order the parts and finish the kit. Stay tuned......