Support for throttle pusher type idle valve .

[hexdmy]

So I'm wondering if it is possible to use a throttle pusher style idle valve instead of stepper or pwm type air bypass valve. Specifically considering this for ITB applications where it is preferable or not possible to have a air bypass valve. These are readily available and were used on many vehicles from the 1980's and 90's. They use a small dc motor, I believe they pull less than an amp to operate. Curious if anyone has tried to do this, or if it is even possible as I'm not quite sure how you could implement this in the software. Looking for any suggestions. 

[Adamw]

I have never seen one.  Is it a brushed DC motor or a stepper?  How many pins on the connector?  How does it know its position?

[hexdmy]

I've actually ordered one to have a closer look, but I do know that it has a four wire connector, two of the wires connect to a small brushed DC motor, the other two connect to a switch that closes any time the throttle arm contacts the idle motor. Some time ago I worked on a few vehicles that used these motors and from memory when you opened the throttle this would act as a dashpot, extending and then closing when the throttle arm came in contact the the motor.  Mitsubishi cars from the 1980's with throttle body injection also used this type of idle motor but they did have a dedicated idle motor position sensor in addition to the switch that detected when the motor contacted the throttle arm. 

[Adamw]

You need some kind of feedback to be able to control position with a DC motor as the speed it moves at will vary with load, temperature, battery voltage etc.  With that device on its own the ecu would ever know what position it is in, you would need a further position sensor.  With a stepper motor they move an exact increment with every pulse sent to it, so the ecu can home it before starting or after stopping to get a known position, then from there it can just keep count of how many pulses in each direction it has sent to the stepper.  With a solenoid they move to the same position everytime proportional to DC so its position is known.  With E-throttle you have TPS to feedback position.  

You couldnt use TPS for position of the idle motor as TPS is affected by both the drivers foot and the motor so often wont be relevant to motor position.  If you fitted a steeper motor to that gearbox it could probably work with nothing extra. To use as is would need a dedicated position sensor and a new control function written into the ecu.   E-throttle would probably be an easier option at that point.

I've been meaning to buy a VW A2C53248883 to try as a cheaper ITB DBW actuator one day.