However, if the ignition time is too long beyond a certain point in the combustion process, it could lead to pre-ignition and pre-combustion – this uncontrolled engine ignition is also known as engine knock. Note: During testing, please use a higher value ("5" or similar) in the idle/low area to "get back to normal ignition timing" as fast as possible.At high engine speeds, the control module is in charge of turning on the ignition timing, allowing the air to fuel mixture in the engine enough time to burn and combust at the right time. In the above example at the red cursor, an advance rate of 0.010 degrees/second is used, which means it takes 100 seconds to advance back 1 degree of timing. The advance rate table, specifies the rate (degrees per second) the system will advance back the already retarded ignition timing (from the knock correction accumulated value) per second, when the knock values are below the values in the sensitivity table (which means the engine is not knocking).Īn example rate of 1 degree/second means if the system has detected knock and retarded 10 degrees, it takes 10 seconds for the system to get back to normal ignition curve, if no further knock is detected during this time period.
![knock sensor knock sensor](https://cdn.shopify.com/s/files/1/2020/3709/products/s-l1600_73321739-9520-449d-855d-a75472c87570_1024x1024.jpg)
The table that advances back the retarded ignition timing to the normal level at a given rate, each second, specified in degrees/second. In the above example, the "25" value from the table is never used since Max accumulated retard is "10" in our example. Note: The Max accumulated retard is always the max ignition retard that can be made, regardless of the above table. The minimum step size is 20% of the entered retard step size value when this setting is used.įill the above table with maximum retard angles at different load and speed considered to be safe for your particular engine. progressive - Decreases the amount of retard for frequent knock events to prevent retarding too much.fixed size - Always retards the same amount for each knock event.Specifies whether to use a fixed retard value for each knock, or use an progressive mode. Number of degree to retard when each knock is detected (by using the sensitivity table ). The maximum retard the system can ever make.
![knock sensor knock sensor](https://www.thevehiclelab.com/wp-content/uploads/2021/05/knock-sensor.jpg)
Determine sensitivity on the knock sensors and populate the sensitivity table Note: The above FAST value is too fast to get updated in the live-logger, it must be logged using the internal logging system at 1000Hz, therefore we have the Knocklevel CYL X peak available.ģ. The peak value of the individual cylinder knock(s) detected (highest value of the last 200ms of time) <- For the tuner to easy up the task of finding knock(s) since this value will always be visible in the live-logger.Īverage knock level value (updates every combustion cycle) <- Used by the Max圎CU to determine engine knock. If this value is retarded for to long period (according to you), you have to increase the advance rate table values to advance back faster. This is the "stored" knock retard value, it can never be bigger than Max accumulated retard value. The above is a good example of handy RealTime Data values to have visible in the live-logger during Knock tuning.Ĭurrent (and actual) ignition retard being used right now.Īccumulated retard value. Use with caution!Ī cam synced trigger system is highly recommenced for a dual sensor knock sensing system.įor single sensor knock detection cam sync is optional (but the knock results might be logged on the wrong cylinder). WARNING: The Knock retard functionality in Max圎CU is a tool to detect engine knock, but with wrong settings it can cause engine damages. Note: All Max圎CUs have support for external knock functionality, more information on external knock control. Max圎CU RACE/PRO has built-in advanced knock sensor functionality. Note: Only use if 280% certain what you are doing! 110% means the individual cylinder sensitivity values is raised by 10% on that particular knock sensor values seen by the ECU. Enables or disables the individual cylinder sensitivity adjustments, only used if the knock sensors values are different on different cylinders.ġ00% means it uses the knock sensor values on that cylinder without no correction (default value).