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Discussion Starter · #1 ·
It seems that when you deactivate the std. boost solenoid and use a different way to control boost (ex. HKS EVC), the knock sensor will not work anymore. This is because the ECU does not get any boost imput.


If this is the case, a very important safety mechanism in our Evo's will not work.

Discussion Starter · #2 ·
N. Ring,
The ECU doesn't get any boost reading anyway, all it reads is the airflow meter and calculates using temperature the mass of air going into the engine.

Disconnecting the boost solenoid will mean that the ECU can't reduce the boost when it senses knock because the ECU cannot control the wastegate actuator as it is now controlled by an aftermarket controller.


Discussion Starter · #3 ·
totally agree with andy

however i thought like most ecus it will retard the ignition it senses knock.


Discussion Starter · #4 ·
How did you arrive at this conclusion.

AFAIK the operation of the solenoid in a knock situation is independant of the knock detection operation within the ecu/knock sensor circuit.

The knock sensor is the input - tuned piezo-electric accelerometer
The ecu processes the signals from the knock sensor - filtering knock noise from the other usual engine background noise.
The output from the ecu on detecting knock is to retard the ignition and close the boost solenoid to reduce boost to a minimum.

I see no reason why disconnecting the boost solenoid should prevent the knock detection circuit and the ignition retard from working. The only problem will be the lack of boost protection offered by the closing solenoid.

On the DSM forums people claim that 'ticking' hydraulic lifters can cause the ecu to be fooled into permanent knock detection with a corresponding lack of power.
Also some connect an LED to the boost solenoid circuit to view the activation of knock control.
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