For those of you who don’t know Ion sensing is a method of measuring combustion chamber pressure using the spark plug. It involves high voltages measuring the current flow across the spark gap, and the current flow is roughly proportional to chamber pressure. This can be used both for detonation detection and for closed loop ignition timing for maximum torque. This can be used for both best power under all conditions or for best efficiency under all conditions.
After a few failed attempts I now have Ion sensing working on my 2004 Mazda Rx8. I am currently moving forward for closed loop ignition timing. One of my end goals is to push the lean limit of the engine while advancing timing for high fuel economy.
Here is what I have so far.
Testing Ion sensing on the bench:
First test of the piggyback ignition timing connected to the car without coils:
Second test of piggyback on the car with ignition coils, and with the car running:
First test of Ion sensing on the car, shows Peak Pressure Point relative to TDC:
Next test is going to be measuring PPP while driving, and after that I’ll be trying closed loop timing at idle.