Has anyone experienced engine pinging under hard accleration?
it has happend to me twice, first time on flat ground and most recently accelerating hard up a steep hill, it was really loud and I backed off the pedal immediatly, after reaching flat ground i punched it again and it was smooth no ping.
Is this normal? what do you folks think?

 

That's knock. Most likely to happen during high loads like you describe, when cylinder temps are hottest - or in your case maybe you had to be at a high load for some time before it occured. Then when you were able to back off, temps drop, and brief period of a higher load isn't enough to trigger it. A little bit (trace knock) will not hurt your engine. If it is really intense and lasts then that is a problem.

Be sure you are using at least 87 octane.