Curious Timing Issues
 

I was running on the highway today tuning spark. The timing map i started with looked like this:
Attachment 206336

With ~13 deg timing @12psi in the 3k-4.5k RPM range, I would get unstable MAP readings, a little hesitation, and my knock sensor would go off if I stayed in the gas. I back timing off 3 deg in boost across that RPM range, and no improvement with anything.

Then I go the other way, and advance 2 deg from base to ~15deg @ 12psi. Now, MAP signal is much cleaner, knock sensor is quite, and the car pulls silky smooth and eagerly. WTF... I thought reducing timing would remedy knock, but this is just confusing to me. I'm not complaining... it's seems like the best of both worlds :laugh:, but am I missing something?

I ended up with this timing map:
Attachment 206337

Here are two pulls:
Base timing:
Attachment 206338

Adv timing:
Attachment 206339

FYI, I'm running 94 octane Sunoco.