I was in a minor MVA at 14,220 miles. They pulled the radiator & didn't burp it properly. The tech said there was "tons" of air in the system & I had to bring it back twice & the third time they refused to burp it again even though it wasn't running as cool as pre MVA.

Within 500 miles of identifying this & only around 15000 miles on the car I start getting pinging or detonation at this specific 3000-3400rpm range. I seem to have lost some HP & fuel economy as well.

Any suggestions? Crank sensor, Cam sensor, MAF? I have no codes. It doesn't seem to do it in closed loop. The shop was clearly derelict but I have been ill & have only put 2k miles on this car since the MVA in 2012. I just want to get this fixed & move on.