Can anyone help please with my basic idea for a car rev limiter that needs to high side switch the ignition feed to the fuel injectors normally driven by the ECU.
The ECU has a common ignition supply voltage at the top of each injector coil via an engine control relay and individually switches the ground to open the injectors in turn. I want to hook into this ignition supply and inhibit it above a preset rev limit.
Using a pic micro based shift light I can get a tacho signal which brings on an led above a set rev limit so I need an interface to modify this led o/p and drive an NPN high side switch to inhibit the injector supply. Please see the attached circuit for my initial idea using components available from UK supplier Maplin and help me calculate the resistor values including power ratings. Alternatively any ideas/ improvements comments are welcome.
The ECU has a common ignition supply voltage at the top of each injector coil via an engine control relay and individually switches the ground to open the injectors in turn. I want to hook into this ignition supply and inhibit it above a preset rev limit.
Using a pic micro based shift light I can get a tacho signal which brings on an led above a set rev limit so I need an interface to modify this led o/p and drive an NPN high side switch to inhibit the injector supply. Please see the attached circuit for my initial idea using components available from UK supplier Maplin and help me calculate the resistor values including power ratings. Alternatively any ideas/ improvements comments are welcome.