Valves rattling under load at 4K RPM (U7192)

[tomp]

Getting some valve rattling when tranny downshifts and places heavy load on engine about 4K RPM. Doesn't sound like ping or knock.

-Hummer H2 with U7192
-87 octane tune and pulled -5% out of timing at WOT from 4-7K RPM
-still occuring after removing timing
-running 87 octane

Any ideas?

[mikel]

Could be a mechanical condition.
Do you see any KR when this happens?
Are you using a good brand of gasoline?

Thanks

[tomp]

Assuming that the monitoring capability is realtime and not a logger, I think I need a passenger to watch the screen to see if KR is kicking in, right?

Just using random available gas at the moment

Two things to try, thanks....

Will gather more info using these two above and will report back later