A challenge for the electronics gurus

[prof315]

I have a challenge for all the electronics gurus out there. I am currently running my MS3/3X on a basically stock 97 2.0L VW 8V motor code ABA. Well all pre-Drive by Wire OBD2 VWs and Audis use a throttle body with built in idle control. I have it _sort of_ working with PWM warm up control but closed loop is out of the question. After doing a bunch of research and testing I have come to the conclusion that the idle motor in the throttle is actually a bi-directional DC motor.

Sooooooo....... can anybody out there come up with a practical way to properly control this d*** thing? It does have a second TPS built in for position dectection and I could provide a factory ECU and throttle for reverse engineering purposes, but this is way beyond my skill set.

Jeff

[elaw]

Doing that right would not be easy - it would require a combination of custom hardware and firmware changes.

Hardware-wise, you'd need what's called an "H-bridge driver" to feed the motor. That driver would basically have two signal inputs: one to increase the throttle position and the other to decrease it. You might be able to use something like this: https://www.sparkfun.com/products/9670 although it's only rated 2 amps which I'm not sure would be enough. The inputs on that module would have to be connected to two outputs on the Megasquirt.

Then, the firmware would have to be modified to send the appropriate signals to the module at the right times. That's the fun part! Although it might not be that hard, there are probably "increase" and "decrease" hooks in there already due to the stepper capability.

[SymTech Laboratories]

The stepper motor driver IC on the MS3 card is a dual H-bridge driver. It can drive a bidirectional DC motor by connecting the motor's leads to IAC1A and IAC1B, or IAC2A and IAC2B. Granted, it can handle less current than the SparkFun module: ~750mA.

[piubrazil]

Not need to make firmware changes. Just the PWM signal from the Fidle set to 100Hz and this circuit:

Vag Throttle controller.PNG

[prof315]

Not need to make firmware changes. Just the PWM signal from the Fidle set to 100Hz and this circuit:

Vag Throttle controller.PNG

Nice! Do you have a components list?