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Knock is one of the most harmful conditions for an engine to encounter and can happen due to a myriad of reasons. The result of knock is isolated areas of extreme pressure inside of the combustion chamber which can damage pistons, rods, vavlesvalves, plugs, and bearings if left to run rampant over time. Most commonly knock is caused by poor quality fuel with lower than advertised octane, high charge temperatures (dead low temp circuit cooling pump), wrong map slot (too aggressive of a map slot for the octane), or oil contamination. We monitor knock for every cylinder and the engine safety for knock can be triggered in two ways:

• Multi-Cylinder Knock Count (6) - This will trigger if three or more cylinders are above the calibratable knock threshold set for that map slot. The higher octane slot the lower the threshold will be. This is due to already increased cylinder pressures typically associated with higher octane fuels.

• Single Cylinder Knock Count (5) - This will trigger if a single cylinder has a stronger knock event than any other cylinder. Typically set slightly higher than multi cylinder but is set to trigger in the case that only one cylinder is knocking.

Short Term Fuel Trims (STFT) are a measurement of the percentage of fuel which is added or removed based off of o2 sensor feedback. If STFT is 20% this means that 20% more fuel is being added than the model commanded to reach the target lambda, or air/fuel ratio. Fuel trims tend to waiver waver over normal driving conditions but is limited by +/-25%.

• Short Term Fuel Trims (Delayed) (7) - This will trigger if short term fuel trims are too high for too long. In a typical street car application this value is set at 24% with a 500ms timer while over a calibrated load threshold.

• Short Term Fuel Trims (Immediate) (8) - This will trigger immediately if short term fuel trims max out. This is typically only used in motorsport applications and rarely on street cars.