93 octane cures the spark knock in my B230, I tried 87 after checking the timing (which was in spec)it started pinging again under normal acceleration , knock sensor wiring checks out ok per haynes backprobe voltage test (2.1 volts), disconnecting knock sensor produces no change in performance!Idle and acceleration are normal. I Would rather be sure than spend $45 on a non-returnable part. I have also checked thouroughly for air leaks, have also installed a new water pump recently and engine temp is never out of healthy range, fluhsed engine to remove any deposits, it didn't seem to break loose anything, clean engine to begin with I assume, thanks for any tips.