I actually was surprised you said there is power loss "particularly if there is NO pinging", as I would see it the other way, if there IS pinging, then extra advance will cause a power loss.

You want your spark to happen such that maximum cylinder pressure occurs right as the piston is starting it's down stroke. If it happens sooner (piston is still on uptroke) it will ping/knock. If it happens later (piston is already travelling down), you don't make maximum power. Therefore it's common knowledge in tuning to advance timing to just before the knock threshold for maximum power.


So assuming Bosch Motronic is working right (knock sensors retard timing if necessary), if chip A is running 10 degrees more advance than chip B on the same octane fuel, and not knocking, chip A is making more power on timing alone. My test results would seem to agree, as the chip making more timing accelerated faster at points where airflow was the same between chips.

2000 6-spd