thanks G G, we learn something every day.
I run 93 ,,99% of the time ,, some times i'll put in 103 ,, and yes the car runs a little better. the main thing to have is a AFR gauge.
it also takes the ecu a amount of time to adjust to the new octane, some times it may take 3 to 5 miles, any changes you make the ecu has to adjust, so yes running 89 oct. then switching to 91 or 93 the knock sensor would entice the ecu to change to make the engine run properly
Your engine in these cars will tell you everything if you just listen example: about 3 weeks ago i found a few drops of oil on my garage floor. went to find the leak, (found front seal leaking), took everything apart to replace the seal and find out why! replaced the seal and was going to reinstall the pulley when i felt a bump on the sealing area . after inspecting the pulley I found it cracked causing the oil leak and telling me something is wrong,,, the engine said, fix me before i explode the knock sensor did not pick up anything, but it was replaced just incase. jim