Knock Sensor Feedback and Detonation - Disable the Knock Sensor on OBD1 ECU's
Unfortunately, the stock knock sensor board on OBD1 ECU's does not interpret knock sensor feedback very well. In fact, it often interprets engine background noise on built engines (from piston noise, noisy valvetrain, etc.) as knock, thus retarding timing when unneccesary. In addition, it often does not detect knock at high rpm when it is actually occurring, right when the engine is most susceptible to damage from detonation. If the tuner has tuned the engine relying on knock detection to retard timing, the knock may not be "seen" at times and result in detonation/pinging.
For these reasons, we recommend ALL OBD1 ECU setups have the knock sensor disabled, regardless of whether or not you are using an ECU that has a knock board (ie: P30, P72). The tuner should "listen" for pinging, as well as periodically check the spark plugs for signs of detonation while tuning the engine to avoid detonation.