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Navigation: Advanced > Knock control

External knock control

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MaxxECU MINI/STREET/V1 does NOT have built-in knock sensor support, but external electronics can be used to achieve a simpler knock control feature.

MaxxECU RACE and PRO has true built-in knock control which can be found here.

 

 

Example external knock detection electronics

Phormula knock analyzer KS-4 - 0-5V output

Plex knock monitor V2 - optional CAN bus output

 

 

External 0-5v knock detection electronics wired to MaxxECU analog input channel

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In the above example an external knock detection tool with analog input connected to the MaxxECU analog input 3 (AIN 3). The calibration table is scaled from 0%(0V) to 100%(5V) where 0% is no knock and 100% is probably knocking like hell. Inputs --> AIN.

 

 

Usage of the external knock value (0-100%)

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By using an extra ignition table (Tuning --> Extra ignition table) we can directly lower ignition based on knock level from external source.

 

 

Advanced warning based on knock level from external source

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Activate MaxxECU advanced warning system. The above example MaxxECU will warn the user when the knock level is 30% and above 80% we completely shut down the engine. If MDash is connected to MaxxECU, the user will get on-screen warning and can take further actions. The warning system can also trigger an output.

 

 

 

Combine MaxxECU advanced functionality for external knock control

To give you a good example of the flexibility of MaxxECU, here is an example of how things can be done in MaxxECU.

 

 

1. External knock electronics wired to MaxxECU analog input 3 (AIN 3)

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Inputs --> AIN 3 (0-5V). 0V = no knock, 5V = knock as hell.

 

 

2. Add an internal counter to increment counter when external electronics detects detonation

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In the above, each time the external electronics send more than 20% knock level, MaxxECU internal counter 1 is incremented.

Advanced --> Internal outputs.

 

 

3. Add an internal output to decrement the knock count value when no knock detected within specific time

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A new internal output (Advanced --> Internal outputs) is created to decrement the Counter 1 value (which represents number of knock levels above 20%).

If no knock level above 5% is detected during 10 seconds (turn on delay), Counter 1 value is decremented one step.

 

 

4. Knock level counter settings (Counter 1)

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Right now we have the following:

A RealTime Data value for knock level (User AIN3) with a 0% to 100% knock value

A RealTime Data value for knock levels above 20% (Counter 1)

 

Note: All RealTime Data values can of course be used in advanced warnings, and also be showed on MDash tablet.

 

 

5. Lower ignition timing based on the knock counter (Counter 1)

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By combining external knock level electronics, internal outputs and a counter we have a very advanced knock control function.

 

 

 

Summary:

1.External electronics detects a knock level above 20%.

2.A counter is incremented by 1 each time a knock level above 20% is detected.

3.When 2 knocks (knock level above 20%) are detected, ignition is retarded using extra ignition table.

4.If engine continues to knock even when ignition is retarded, more retard is required when Counter 1 is incremented.

 

 

More knocks --> More ignition retard.

No knocks during a time period --> Less ignition retard.

 

 

Note: Use with caution...