Type R Club of America

aklackner wrote: ↑Wed Apr 29, 2020 6:13 pm From what I've understood, an over simplified explanation of the OEM knock sensor is that it's basically a mic, tuned for a specific frequency that Honda associated with pre-detonation on an OEM motor.

Engine modifications, specifically aftermarket\forged pistons but other mods as well, change engine vibrations\frequencies. This means you have an increasing chance of issues with accurate knock detection as modifications get more significant.

Obviously, if depending on knock detection as a safety measure, failure to properly detect it increases risk as there's an assumption pre-detonation will be automatically addressed. This is even more true where otherwise a tune may be more conservative or implement other measures such as an increasingly rich fuel mix. False positives with OEM knock detection on the other hand, will pull timing\de-tune and create inconsistent performance even-though the tune itself maybe appropriate.

There's also the issue that many Honda B-series knock sensors fail over time (plastic separates from the metal) and aftermarket replacements may be questionable. Testing a knock sensor for correct function (with your motor) isn't as approachable as testing other sensors. Identifying false knock sensor positives, as a source of issues, can be an unwelcome complication for tuners.

With highly strung motors, running OEM cast pistons, chances of damage prior\coincident to detection of knock is increased over an completely OEM motor not faced with raised pressures of a tuned motor. The further a build is pushed it's generally better to plan a sufficient margin to avoid knock than to depend on reaction to it.

All the above, and likely an inclination to expect customers to be less reliant on OEM protection measures, can lead tuners to advise against attempts to enable the OEM knock sensor even when available. So I highly recommend checking with your tuner what their preferences are.

If your tuner does recommend use of the OEM knock sensor you'll need to find a P72-A01 (US 94-96 GSR) ecu which is one of the few US OBD1 ecus to have the additional knock board (sits above the ecu main board). There may be a JDM ecu that has the knock board but then you'd need the JDM ecu specific s300 setup. Alternately I believe some AEM ecus may provide similar options to safety sensors and some tuners will prefer this route over Hondata.