does the stock ecu automatically advance timing if you put better octane gas in it? I am thinking about running 100 octane.

 

As far as I know, no it doesn't.

It has a fixed map, and can only retard when it senses knocking, not advance when it senses higher octane fuel.

 

If you go to a higher octane fuel, you should reset your ECU. If your ECU has been retarding timing, it will continue to do so for a while if you don't reset it. After resetting it, the engine will run strong, but the idle quality will suck for a day or two.

 

how do i reset the ECU?

 

I have to agree with gernby, that will likely yield the best results for you. The ECU will only advance / retard timing based on intake air temp, knocking, air quality (density). You can reset it by pulling the fuse by the drivers kick panel just rear of the ECU. I don't recall the fuse number but will look it up tonight when I get home if someone hasn't posted it for you by that time.
-BS2KT

 

I think it is fuse #25.

 

Check out the library. https://www.s2ki.com/article/articleview/5/1/15/