[E36] Excessive pinging

[Jason M Surprise <jmsurpri@xxxxxxxxxxxxxxxx>]

I'm bringing my 94 325i with 74K miles into the shop on Friday to
diagnose a pinging.  My car has been pinging off and on for about a year
now.  Lately I've noticed that it's much worse than I've ever heard it.
For example, driving in any gear with very light acceleration on a
flat road, it pings almost nonstop until about 3500rpms.  The car still
seems to pull quite strongly over 4k rpms though which is strange.  I've
tried different brands of gas, different stations, different octanes and
it doesn't help.  I've tried replacing the fuel filter and spark plugs,
no help.  Can anyone offer any suggestions on what other reasons could
cause pinging like this?  If they tell me it's a faulty knock sensor,
should I buy it?  It seems to me that a faulty knock sensor won't fix
the pinging problem.  When fixed, it'll mask the fact that there's a
real problem, won't it?  Also, I don't want the shop to give me the
usual line of blaming it on bad gas, or telling me it's hard to diagnose
pinging problems. 

Thanks,
Jason

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