My dad's knocks like there is no tomorrow. It doesn't seem to matter what he does. It has always been that way.
There are a couple reasons why a FF 3.0 will ping.
One, it may need the PCM re-flash that was the subject of an NHTSA notice.
Vehicle Make - Model - Model Year(s)
FORDRANGER1998-2000
Service Bulletin No.: 00248
Component(s): ENGINE AND ENGINE COOLING NHTSA ID Number: 616536
Details
0 Associated Documents Manufacturer: Ford Motor Company
SUMMARY
SOME VEHICLES EQUIPPED WITH A 3.0L ENGINE MAY EXHIBIT SPARK KNOCK (PING) UNDER ACCELERATION. *TT
Two, the EGR DPFE fails and causes pinging. They also are prone to EGR carbon build-up which clogs the EGR passages.
Clearing the CEL will only make the computer "learn" that the bad DPFE signal is supposedly "good".
Pinging is fixable, you just have to zero in on the actual cause.