Boost bleed valve

[BMWRallycross]

I have an supercharged engine with cable throttle and was thinking if it is possible to use the E-Throttle function to control an small electric throttle body to bleed of boost?

Does it work if I change the Y axis of the target map to use an rotary position switch instead of an pedal sensor or does that introduce an error?

[Vaughan]

Yes you could use the 2nd E-Throttle functionality to control a blow off valve style setup, a generic H-Bridge function is on the list of things to do. Note several european vehicles came from the factory with two wire solenoid controlled blow off valves which don't require H-Bridge control or if you have a conventional BOV you could put a solenoid in the manifold pressure feed to it.

Note it can be difficult to sit an E-Throttle on fully shut consistently without tripping the fault codes and I'm not sure how well it will seal.

[Laminar]

9 hours ago, Vaughan said:

Note it can be difficult to sit an E-Throttle on fully shut consistently without tripping the fault codes and I'm not sure how well it will seal.

How difficult would it be to modify the spring setup of an E-throttle so that the default position is held closed with a spring like a traditional cable throttle? Would that help minimize overheating the motor trying to hold the valve closed all of the time?

[Vaughan]

11 hours ago, Laminar said:

How difficult would it be to modify the spring setup of an E-throttle so that the default position is held closed with a spring like a traditional cable throttle? Would that help minimize overheating the motor trying to hold the valve closed all of the time?

The difficult part is less the motor and more holding it at 0% without tripping the min dc limit fault, either 0% is just off closed so it can reach it happily but it isn't sealed or it's just passed closed where it can't reach it so it maxes out the duty and the throws the code.

If you get it just right you can have the throttle plate shut and the 0% in just the right spot so that the motor backlash can be taken up but still leave some room for movement so duty doesn't max out.

I'm not sure if the min dc fault is checked in setup mode.