The MDI entity posted thusly:
X-No-Archive: yes
>
>Anyone know what a pinging(?) noise from under the car around 1500 RPM
>during acceleration may be?
>
>(The sound is suggestive of something lightly striking a hollow metal
>object, something like 3 times a second. No idea what actually makes the >noise.)
>
>The car is automatic, about 9 years old.
I have a 2000 F-150 that does this. Turns out it's one or more small stones in a shield around the muffler and/or tailpipe.