Just made one of my greatest breakthroughs yet! While driving around lately, it seemed like no matter what I did to prevent ping, I would. It was getting frustrating. Retarding timing to the point of loosing that "throw you back" feeling. Adding fuel little by little to get my A/F ratios a little lower. "Krackle-Krackle!" is what I would here..almost as if my car was making fun of me. Last night a lightbulb came on. (thought)
The crackling was happening mostly at partial throttle after I had nailed it, got some serious speed, and then was backing off the throttle slithgly and holding the position. Then it occured to me that I had turned my closed-loop control back on after I "thought" I was about done road-tuning. It has a maximum throttle position setting which I had set to 25%. What this meant is that it would try to do A/F correction to around stoich (14.1:1 A/F) up until I passed 25% throttle. That means that at 26% throttle, I would go open loop finally. With the new setup, the turbo spools up considerably faster, and this, I realized wasn't going to cut it. I adjusted the setting to 15%, and the pinging went away, but I bogged rich too soon. I set it to 20% which seems to be the magic number. I did some partial throttle tests on the highway at that setting to see when the boost threshold would be crossed, and at what throttle postition that was. It worked! So for the final test, I loaded up one of my previous maps with more timing, and nailed the throttle. Where's the ping? Didn't hear any! Getting the hang of tuning this thing. If only I didn't have to drive while doing it...