Our previous Programmable Ignition was originally published in March 1996 and proved to be a very popular project with readers. This was subsequently updated as the Programmable Ignition Timing (PIT) Module in the June and July 1999 issues of SILICON CHIP.

The updated PIT module included a basic 2-step advance curve and a 1-step vacuum advance that changed the timing according to engine load. In operation, it was used to control the High Energy Ignition design from the June 1998 issue.

This latest Programmable Ignition from SILICON CHIP is far more advanced in features and its ability to produce an accurate advance curve. It is also a complete stand-alone ignition system that is triggered by an engine position sensor and then drives the ignition coil. It can be triggered from one of many sensors in a distributor, including points, reluctor, Hall effect, optical trigger and the 5V signal from the car’s Engine Control Unit (ECU).

In order to measure engine load, the Programmable Ignition can use a Sensym absolute pressure sensor. In fact, provision has been made to mount this sensor directly on the PC board, the sensor then being connected to the engine manifold via plastic tubing.

Alternatively, you can connect the ignition circuit to an existing manifold pressure sensor if present. This is commonly called a Manifold Absolute Pressure (or MAP) sensor and is found on many cars these days. You could also use a secondhand MAP sensor from an auto wrecker.