Ok, so I brought it back to him and so far he's unable to detect the problem. Right now the timing is fully retarded, if we try and advance it one bit it starts pinging more. It doesnt ping in neutral, and it doesn't ping at high rpms, it only pings at low rpms. The freaking guy is trying to tell me that this is normal, that I shouldn't worry about it, but I told him FU, and I told him to fix it. I'm furious right now.