What causes the pcm to revert to the lower octane table?
Obviously if you run lower octane it should revert to the low table but how does the vehicle tell what octane you are running
What conditions are a deciding factor when it comes to choosing high/low tables?

 

i believe that the conditions are the pcm finding knock at so many intervals that at one point it will revert to the low octane table. i believe that it will keep checking to go to the higher table.temps may have a big effect on it as well.

 

Excessive knock ... it tries the high octane tables again after so much gas is added to the tank, it's a percentage, don't remember how much though. For some reason 80% is sticking out in my head.

 

I think its more than knock because I have no knock and it will still revert to the lower table. Thats what I cant figure out, me and gamedawg have been talking about this and tuning and he thinks there are some more tables that we cant see with hp tuners that gm uses.

 

where can I find info on what tables use what sensors and what factors are involved

 

this is from horist in the tuning section,

Several things determine... the octane of the gas you use doesn't matter unless you get knock

more knock = closer to low octane, less knock = closer to high octane... it's not a yes/no , use high or use low... it's a blending of both

having a knock sensor code, failed MAF, probably failed MAP and O2 sensors as well (basically if any of the primary sensors fail, it'll go into a limp mode and use the low octane table excuslively)
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why even have a low octane table? meaning, why not have the low octane be exactly the same as the high octane table?

 

that is why they say run 93 or 91 octane on a hot tune. they past the high octane tables over the low octane tables.

 

That is what I did i copied my high octane the the low octane table.

 

mine never shows knock
but will revert to the low octane table if its set
higher than the high octane table

I went down the road logging after setting the adders where
they wouldnt affect the timing
trying to start at a low # to try to make runs to find optimum timing

well after i looked at the first run it was higher than what I set
in the high octane table
it used the same #s in the same blocks as the low octane

after a copy paste of high to low octane, the numbers I expected to
see were there

one would think it searches for the highest timing (consdering no knock)
reguardless of the tables high or low

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Im just wandering for your setup
what would be close to the best timing and afr
12.5 and 26-28*
thats a guess
should be someone here that can get a little closer
thats been there done that
might want to start a new thread