In warm weather when I push my car, I hear mild detonation like "click, click, click, click" near my engine bay. It usually happens in the top of 3rd and 4th gear. I don't think I should be leaning out on high rpms because my vafc was tuned on the dyno to be running a little rich to protect the motor. Any ideas of what the problem is? My setup is 320cc inj, intank fuel pump, 8:1 fmu, and vafc.

 

whats your a/f ratio