Manually moved from DIY PROM:

Ok I have searched with no results (can anyone point to where the answer is if answered) but the Question is:

Can the ECM Computer be preselected to run a certain ROM (user inputted) based on Octane of gas in the tank or can a custom computer be built to do this function or even on the fly (while running) although the last scenario is highly unlikely?

The reason I ask is because based on the current escalating fuel pricing I was hoping to have optimized programs for running either Premium, Ultra(Sunoco) or Regular.

The car from the factory recommended running premium but I know for a fact it has in past run on regular gas

 

You can switch between binaries on the fly with tunerprort using hardware such as autoprom or Ostrich 2.0.

Personally I use Ostrich 2.0, you just upload a new binary and it automatically takes effect.

If you were REALLY good, you'd make a digital input to your car computer, so you can just press one of 3 buttons on your dash, and it automatically uploads the correct file to whatever emulator you are currently using... Thats what I'm working on doing, but more for mileage vs performance than differing fuel types.

 

If you are still running the factory stock ECM in your '91 TPI it already does this. There are low octane routines that keep track of knock. With enough consistent knocking the ECM will reduce timing to account for lower octane fuel. Each time the ECM is keyed-on the routine resets back to full timing.

RBob.