It sounds like my truck (3.9) is pinging- but only going 60+ MPH on the highway. I havent driven highway in a good 2 months to have noticed it. Keep in mind I have 4.10 gears no, so I cruise around 2200-2400 RPM.

It'll make the noise on the throttle, but goes away when I coast.

But when i put it in first or second gear in the city, it won't do it (similar RPM range). Even when I rap it up to 4500 in first gear.

BUT, I will hear it- just a touch- in the city, if and only if the oil pressure is real high- over the high hashmark. Normally it's midrange at 35 MPH and on the low hashmark at idle, at normal operating temp.

I'm running 93 gas on the tune that came with my refurb PCM- I still haven't hit it with my SCT yet.

It won't do it when I put the engine under max loading, on the converter. This is with the e-brake on, pulled up to a curb, both pedals on the floor. Stalls exactly to 1600.

(of course, my phone was set to record without audio for some dumb reason, I'll re-do and re-upload tomorrow.)

http://www.youtube.com/watch?v=cXKTLrVqMTY