Mpg display different from trip 1 avg to general avg?

[01ssreda4]

That's interesting...
All the octane related info i could find on this forum and others basically say:
early generation denalis 01-03 (LQ4) can run either 87 or 91 - The engine will actually adjust timing depending on octane. 91 should give a little better perf
later generation (LQ9) are higher compression and therefore require 91



so which is it?

Listen close.....there are TWO timing tables. The computer decides which one to use based on how good it thinks the fuel is burning. The better table only has a few degrees more timing in it. BOTH are conservative. BOTH are safe. Either can be used with basically any grade of fuel IMO because they both have ****** timing numbers in them. A healthy running engine wont get knock from either table on 87 fuel. Theoretically, if you ran 93, and the computer recognized it, you get a couple more degrees of timing due to running the "high octane" table.....enough to notice a performance difference, probably not.

 

[igell]

Listen close.....there are TWO timing tables. The computer decides which one to use based on how good it thinks the fuel is burning. The better table only has a few degrees more timing in it. BOTH are conservative. BOTH are safe. Either can be used with basically any grade of fuel IMO because they both have ****** timing numbers in them. A healthy running engine wont get knock from either table on 87 fuel. Theoretically, if you ran 93, and the computer recognized it, you get a couple more degrees of timing due to running the "high octane" table.....enough to notice a performance difference, probably not.

i am with you.. so i assume with a 91 tune from BB your timing is advanced enough to actually get a benefit from the 91 octane. Problem is that it becomes static and then you're required to use 91 to not ping.

 

[01ssreda4]

All depends on how they set it up. I copy and paste to the same thing so the computer HAS to run a single table and there is no variances. It can change all it wants but its going to the same thing.

 

[D is for DENALI]

This is all great info!