Wednesday, November 24, 2010

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..... :banghead 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..... :smackface

~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.