BenK wrote:
Takes more than one tank of higher octane before the ECU will relearn HOW2 manage
Even longer if driven gingerly TRYING to get higher MPG
You must demand power mode often and for long periods of time
So the ECU will relearn to generate a new fuel mapping table(s) for Power Mode, which will also affect MPG
Maybe the OEM has limited the level of Power Mode allowed. So even aviation fuel won't mske a difference and if so, a tune will be needed
Plus there are other attributes in play. Main two are thermal limits and the auto trannys computer algorithms
The computer does not learn anything and the change in output would be instant if you completely cleared your tank of 87 before putting in 93.
The change in power output is based on how much knocking the knock sensor detects. If it does not detect knock then the ECU will allow the valve/ignition/fuel timing to be advanced until it detects knock. When it detects knock then it will pull or ****** timing until it does not detect knock anymore. The computer is constantly pulling/advancing timing so if the octane of the fuel allows it to advance timing then it will do so immediately.
In regards to learning, the ECU does not have the capability to learn. Inside the ECU are a bunch of fuel maps that determines how much fuel/timing to advance/****** based on these predetermined fuel maps. The ECU uses the data from all of its sensors to know what to do based on set parameters. Basically, the map would say that if sensor A, B, and C are reading this, then you valve timing should be X, your ignition timing should be Y, and your fuel delivery should be Z for the corresponding throttle input and rpm. These maps never change unless someone( a tuner) re-flashes the ECM with new maps.
The reason why most do not feel an instant change has more to do with the fact that they probably still have 87 in the tank so they "feel" a gradual change over the course of a few tanks. The best thing to do if you want to see a difference is to run the tank of 87 as low as possible and the put in 93.
