knock sensor bad?

[Peter Jackson]

Knock sensors are listed under the undetectable items section of the
FSM. There is a test for the part itself.
But if the sensor tests good, how can you tell if the ecu is pulling out
timing because of something else or because the sensor is being set off?
An Apexi or Techtom would show the current engine timing, but since it
is always fluctuating, how would you know what the timing should be?

I'm looking for the source of loss of power and slow revving. It feels
timing related but I have double checked mine. I put it at 19 and it
revved much more freely. Now that I have the S3s I put it back to 15 and
it revvs slowly again. I figure the ecu is pulling timing for some
reason.

What else can I check?

Peter J
96 SE-R