Saturday, November 08, 2008

Home made electronic ignition and fuel injection for my 1961 Fiat 600 - part 1

Ever since I got my 1961 Fiat 600 about three years ago I have been thinking a lot about what I want to do with it. Since I have been quite interested in diy stuff and playing around with microcontrollers for a while I thought that electronic ignition for my car would be a challenging project. I have by the way had quite a few problems with making it run well in all sorts of weather with the old points/distributor+carburetor.

After reading a lot and discussing with colleagues who are heavily involved in racing, motors and all kinds of vehicles I decided not only to make my own ignition system, but also a fuel injection system. This is due to the two systems sharing many of the same sensors and modifications would be made on only a few parts.

Last year I bought a waste spark ignition coil, MAP sensor, EGO/lambda sensor, a trigger wheel and a trigger/hall effect sensor. My colleague Ole Mobeck also started making a new intake manifold to integrate the MAP sensor, a central injector and an air temperature sensor.

I removed the cap to the centrifugal oil filter. The filter is connected to the crank shaft and is the ideal place to mount a trigger wheel. I machined the trigger wheel to fit the lid, so now I only need to mount it to the car and make a fixture for the trigger sensor.

The high power part of the electronic system has been a challenge both since I only have a limited electrical knowledge. It has also been a challenge since I know this is dangerous stuff. The voltage through the secondary coil generates approximately 40kV output and could be lethal.

After trying to make an ignition with different transistors bought from online electronic stores and building a ignition system found on the web my releasing moment happened yesterday: Ole Mobeck cut off his Subaru Legacy ignition module and waste spark coil and gave it to me as a "christmas present".

Today I figured out, while Synna was taking her nap, how to connect the ignition coil from a Subaru Legacy wokshop manual. I tested the ignition module in several steps:

1. Check to see if gate was normally open or normally closed. If the gate was normally closed the ignition module would send 12V through the transistor when connected. I connected 12V via a blinker relay to OC1, G to GND and made a voltage divider input with a potensiometer with the central lead connected to IB1. I set the voltage to zero before turning it. The blinker relay started when the voltage was over 12V. This means that I need another transistor to turn on the ignition modul with an input from a 5V microprocessor.

2) After finding that I needed 12V for the igniter I wanted to check if I got a spark. I now omitted the voltage divider. I now connected the coil where the blinker relay was, and connected the blinker relay as a safety to the input of the igniter as shown. I connected a spark tester before one of the spark plugs.

An very tense moment was exchanged for relief and excitement when I saw that I had spark. The test lamp was lighting up and the spark was nice and blue.

The next steps are to connect the ignition to a 555 or a microcontroller and find an okay spark time. In parallel I want to test the trigger wheel and get a nice signal as well as try to finish the fuel manifold.
Posted by Picasa