1983 & 1984 22RE with Megasquirt Ignition
2 Modules - Stock Toyota Igniter and Bosch Hall sensor Module(Easier than internal VR and coil driver in MS)
I built a working spark system for use with an Early Toyota igniter and distributor. This setup can be used with Megasquirt (all versions). My setup uses a Bosch module to drive the coil. The Toyota igniter is simply used as a "signal" feed into the Megasquirt.
The 22R uses a VR sensor distributor. These distributors put out an alternating current, going from positive to negative. This signal cannot trigger a coil or trigger a regular Megasquirt without special modifications. To make it easier, the VR signal must be converted over into a DC signal that is either on or off. This DC signal is the same as a "Hall" signal from most Volkswagen and Chrysler distributors. You can check if you have a VR sensor by spinning a distributor manually and checking the voltage across the 2 output wires. It should register about (.2 - .5) AC volts when turned by hand.
The Toyota igniter box converts the alternating current from the distributor wires into a DC pulse that is either on or off. This pulse controls the coil. When the igniter box grounds the negative coil wire, the coil builds energy. When the igniter box shuts the pulse off (zero volts) then the coil throws a spark. The length of time that the igniter builds the spark is determined by the speed and the distance of the magnetic trigger wheel in the distributor. At a very slow idle the spark will have more dwell and the coil will have a hotter spark.
The early (NON ECU CONTROLLED) igniter module is considered a "dumb" module. This is because it cannot control the length of time that the coil gets to charge (Dwell).
Anyway, this igniter WILL work with megasquirt. Don't throw it away! I figured out how to use it to trigger megasquirt!! The igniter can be retained because it is specifically matched to the Toyota distributor. The igniter does a very good job of converting the alternating current .5 - 50.00 volts coming out of the distributor over into a useable pulsating signal that megasquirt can use.
VR sensor ignitions are prone to radio interference from electrical noise, and the VR signal can get disrupted. That is one reason to retain the stock Toyota igniter. It already has a very nice wire running from the distributor to the igniter box and the system is not susceptible to electrical interference.
The following information shows how to wire up a Megasquirt I with a Version 3.0 board using 2 modules to control spark as well as feed Megasquirt the basic RPM input. The Toyota igniter will no longer be used for driving the coil. Instead, the negative coil wire on the igniter will simply provide a line input into Megasquirt. As always, my method is only one way to do it, but it is extremely easy and cheap.
I will make a wiring diagram tonight for more information. But here is a picture of how I hooked it up. I made my own test ignition on a piece of plywood using a stock 1984 Toyota Celica Igniter. I also used a Bosch Hall sensor module.
The Bosch module that I used is designed for Hall distributors. Hall distributors send out a square DC voltage wave. Hall sensors send a +5 or +12 volt signal and a ground signal that switches on and off. This is the same type of signal that comes from the negative coil wire on the Toyota Igniter. The Bosch module is very simple. Because it uses a simple on and off switch to trigger it, you can literally trigger a Bosch module with a toggle switch. You just need a very small pulsating current. The Bosch module provides the brute power. All you need to do is provide the small signal to it. The signal can come from a toggle switch, a Hall distributor, a Toyota Igniter box, or a Megasquirt output wire.
So here is how it works. In order to avoid using Megasquirt to drive a coil, which puts more strain on Megasquirt, you can use a Bosch ignition module to provide high current to the coil. The Bosch module will absorb the extra heat and load, making the Megasquirt more reliable. The Bosch module is also a "Smart" module that will not overcharge the coil. If you get the right Bosch module, as listed below, you will have automatic dwell control. No other modules except Ford EDIS has built in Dwell control. Normally you have to "guess" at the proper Dwell. Ford EDIS and Bosch "smart" modules are the only ones that allow automatic dwell, that means less hassle when trying to configure megasquirt.
To set it all up, you disconnect your coil from your Toyota igniter. Because Megasquirt needs a regular on and off signal to trigger it, you will need to put a tiny 1000 ohm resistor between the positive wire and the negative wire where your coil used to be. Now throw away your Toyota coil. Run the negative coil wire into megasquirt on the proper ignition input pin. The tiny resistor is necessary because it keeps a tiny amount of positive voltage on the negative igniter output wire when the igniter is switched off. This makes the igniter output wave the same as a "Hall" sensor wave from a VW distributor.
The Megasquirt will read the Toyota ignition pulse like a digital wave and it can process it according to the settings you want to use. For the output, you simply send a wire from the Ignition output on Megasquirt to the Bosch Hall sensor module. The megasquirt sends a tiny low voltage pulse to the Bosch Module. When it receives the pulse, it will fire a coil.
You need to get a Bosch module and matching coil from the same car. Any module with the following part # is a smart module and it will control dwell. Because of this you don't have to worry about burning up the module or burning up your coil, or losing your megasquirt while driving down the road. Even better, unlike an HEI system, the Bosch module can receive a direct full 12 volt signal. You don't need a special relay or resistor to provide power to the module. It is very sophisticated for its size and is very rugged, it comes with a large heat sink on OEM applications. Be sure to get the heat sink and use it!
So here is a summary, if it wasn't clear:
You will use the stock "non-TCCS" igniter to trigger Megasquirt. You will use a Hall sensor Bosch module to receive the ignition output from Megasquirt. This Bosch module will also provide the correct amperage and voltage to drive a coil. It will also provide the correct dwell. The only thing the Bosch module needs is an output from Megasquirt.
First, You remove the stock Toyota coil. Jumper a 1000 ohm resistor between the positive and negative leads on the igniter where the coil used to be. Run the negative coil wire into megasquirt. See the following pictures for more information.
The reason that you would hook things up this way is very obvious. I have researched this a great deal and have found the following benefits to using external modules to run the ignition.
-The coil driver on the Megasquirt 3.0 PCB (the VB921) can burn up if you do not set the Dwell properly with the coil that you are using.
-The Bosch "smart" module can automatically set the dwell period. If used with the matched Bosch coil, you will not burn up the Bosch module or coil due an improper setting in Megasquirt.
-The Bosch module is external and it can be replaced for free with another junkyard module if it burns up. It is easier to access because it can be mounted in the engine compartment. They are waterproof and heat proof.
-The Megasquirt V 3.0 PCB board has an option for VR sensing. This VR sensing circuit is not as user friendly as a Toyota igniter. The VR wires going from the distributor to the computer box could receive radio interference from spark plug wires, or other electrical noise. The internal VR circuit in Megasquirt is adjustable via two tiny rheostats. Sometimes the VR signal won't work and these tiny adjustments must be made on the Megasquirt board to make the VR signal trigger properly. Sometimes the VR sensing circuit works improperly causing sporadic operation of the ignition system. Overall the VR input circuit on Megasquirt is slightly less user friendly and more difficult to implement than a simple existing Toyota Igniter.
-The Toyota igniter is rock solid. It is immortal.
-The Bosch modules are very reliable.
-This system makes Megasquirt far easier to implement for spark on the 1983 and 1984 22RE engines with the mechanical distributor. For more info see pics.
The following Bosch modules are "smart" modules. If it isn't listed here, it is a "dumb" module and it will not control the dwell. It could cause a problem with your coil unless you know how to set the dwell properly in Megasquirt. I recommend using only the smart modules.
BOSCH MODULE NUMBERS#
0 221 600 001
0 221 600 006
0 221 600 008
0 221 600 011
0 227 100 100
0 227 100 101
0 227 100 103
0 227 100 104
0 227 100 113
0 227 100 116
0 227 100 118
0 227 100 137
0 227 100 138
0 227 100 139
1 227 010 001
1 227 010 004
1 227 010 100
1 227 022 008
See next post for wiring diagrams.
