how long for the pcm to notice octane change??

[my_bd]

if i switch between 91 and 94 octane, how long do you think it takes the pcm to notice and adjust??

instantly?
an hour?
a day?
a week?
a month?
a year?

1 mile?
5 miles?
10 miles?
100 miles?
1000 miles?

[AJSINAZ]

It's in the manual I think it said after 3 tanks

[WopOnTour]

Originally Posted by my_bd

if i switch between 91 and 94 octane, how long do you think it takes the pcm to notice and adjust??

instantly?
an hour?
a day?
a week?
a month?
a year?

1 mile?
5 miles?
10 miles?
100 miles?
1000 miles?

It's instantaneous with each key cycle and not really a "learned adaptive" that gets stored in non-volatile memory (like long term fuel trim for instance)
The ignition control system will automatically "attempt" the maximum timing value listed in a table for the existing load:rpm that exists. If it "sees" knock it will then retard the timing until knock is not present and remember by how much (in that cell) for the remainder of that ignition cycle.Once the the ignition has been OFF for about 10 seconds, these adapt values are cleared, so it always attempts to maximize your ignition timing every trip cycle.

HTH
WOT