i3 91 & 93 Octane Tune

[18SS376]

I have a 2018 Camaro SS LT1
If I load the 93 octane tune & then fill up with 91 will it cause any problems?

[06MonteSS]

if you're only using 91 octane gas, then you want to install the 91 octane tune... it has lower timing settings than 93 so it's meant for 91 octane..

the 93 octane tune has higher timing settings made for the higher 93 octane.

[18SS376]

I would like to know how much timing is increased from 91 to 93

[06MonteSS]

depends on the rpm, and load/airflow bud... just for an example, it could be 2* in some spots, and could be 6* in other spots... it all depends... it's not just a flat number across the board...

[18SS376]

The knock sensor will retard timing if it starts to ping, my old '86 Camaro did this & had one of the first laptop programs for cars back then. 6 degrees is nothing if that is max. for 2 octane numbers.

[06MonteSS]

Again, those numbers were just for an example... could be higher than that..could be 10* - 12* higher ... don't have a tune open in front of me.

[18SS376]

What if the fuel doesn't contain any ethanol, 100% 91 octane & then there are some fuels that have up to 10% ethanol in there 91 octane. Does the canned tune for 91 work immediately so I can make a drag pass or does it require driving a certain distance for the ECM to learn?

[18SS376]

Cat got your tongue, do you have an answer for my above question?

[mikel]

The PCM monitors e content and can adjust accordingly if needed.
It doesnt need to learn octane, it figures that out quick, As soon as you hammer it the knock sensors are listening for bad noises and if they hear them, they will ask the pcm to pull timing.