The same sound has been present on my XJ6. In addition to the
reasons you already know, there may be some other causes that
could be possibly investigated without becoming bankrupt :
1 : Fuel mixture to weak (The 12 knows what it wants)
2 : Ignition timing not optimal for the fuel used.
To try out settings around the one which you have now
and running the car looking for pinging rising or disappearing
might be rewarding. But only minimal adjustments !
3 : Engine running at too high a temperature. Check or
install a new thermostat.
My BBS (Big British Saloon) doesn't ping anymore, but of course
the low price of my car is more of a motivation for messing around
with adjustment parameters than on a garage serviced V12.
Good luck
/Gunnar
-------------------------------------------------------------------
Gunnar Forsgren
(__) Ericsson Telecom AB
(oo) Department for Standard Computer Systems
/-------\/ 126 25 Stockholm
/ | G || SWEDEN
* ||----|| mail: gunnar%beppe.ericsson.se@uunet.uu.net
~~ ~~
Disclaimer: I'm acting on behalf of myself.
-------------------------------------------------------------------
|