84 Celica GT Ignitor question

[rlg999]

Hi guys,
I have an 84 Celica GT 22re engine that I am using in another project. I will not be using the fuel injection system or computer. My question is: can the ignitor be made to work without using the computer? What exactly does the computer control on the ignitor, timing, firing??? Thanks for any input. RG

[toyomoho]

In your engine, the timing of spark plug firing needs to be controlled for the engine to work property. The ignition coil needs to be charged and discharged to provide voltage for the spark plugs. In the past this was done using a distributor with ignition points. The ignition points turned the electrical power to the coil on and off. The points followed the distributor cam and opened and closed. This charged and discharged the coil providing the voltage for a spark. The distributor rotor and cap distributed the voltage to the correct cylinder spark plug. This worked fine but the points controlled a lot of electric current and as such arced and burned needing to be replaced often.

Later engines incorporated an ignition module (ignitor) using a similar distributor points setup. This ignition module uses semiconductors to control the coil. The points still controlled the semiconductors, but did so with very little current flow through them. As such, the points lasted longer. This points system was later replaced by a magnetic pickup that triggered the ignition module to control the coil.

Up to now the distributor controlled the ignition timing by a mechanical ignition advance/retard system adjusting to cam RPM and engine vacuum.

A computer was put into the system. The computer was hooked up to sensors providing inputs for RPM, manifold airflow, coolant temperature, etc. The computer adjusted timing to obtain maximum power, fuel economy, low emissions, etc. based on these sensor inputs plus its own internal programming. As such, timing could be varied based on more then just engine RPM and vacuum, and much quickly.

If you have a way to control ignition firing, you can do away with the ECU and even go back to the older points/coil system. I would stick with a solid-state ignition module system. Find a distributor having the older mechanical and vacuum controls that fit your engine. You can then adapt a solid-state ignition control module ignitor to this distributor.