DIY_EFI Digest V5 #17:Knock sensor, etc.

[Bruce Plecan]

| Thanks Bruce,
| I had not thought about noise contribution from mech
| valvetrain. And of course, IGOR will allow some very
| accurate knock detection, but I didn't think it was
| available yet.

IGOR, no, but SAAB's been using it for years.

| Here's a Q, do you know how/if GM systems handle false
| KS trigger, vs RPM?

Nope they don't handle vs rpm, 800 rpm, 2000, 4000, 8000,  if it's set for
4,000Hz, and hears the right sound off goes the timing.  I've seen cars set
12d retard wile cranking.

That's also why I consider acoustic sensors as a joke, and not to be trused.

| For example, say an ECU has a KS sensitive to say,
| 4,000 Hz. Frequency of bormal internal noise from the
| motor varies with RPM, so at some RPM, it will also
| create 4,000 Hz noise that would trigger the KS. Does
| the code ignore KS at certain RPM?

See above.
Grumpy