Providing feedback for a Toyota 6 pin stepper motor

I'm want to use a 6pin Toyota egr stepper motor with my link g4X. There's an option for closed loop stepper control but it only works with a 0 - 5v feedback circuit.

There's no feedback circuit on the motor and from my research Toyota don't use one on the stock setup so I'm looking at how I can make this motor work.

It's essentially the same motor that is used for idle control on supras. I can only assume when you set them up for this in the link the RPM is the feedback.

I've racked my brain about using pressure sensors, temp sensors to give the feedback circuit, but none of them will be reliable due to other variables in the running of the engine effecting their results. The only thing I can think of Is trying to physically add a multi turn potentiometer to the magnet to get a varying voltage when the manget spins.

Has anyone else managed tp get one of these to work?

Is there any "open loop" stepper control. Where a feed-forward or target table is used to just set the position.

Not that I can see, I also have a ecumaster dual H bridge that can do stepper control but again it only looks to be closes loop

The problem with no feedback for a stepper is the only way the ecu knows the stepper position would be to treat it like an idle valve and do some sort of homing routine to a known position after shut down, then once powered up to keep track of position it would need to keep a tally of how many steps it has commanded in either direction. If it ever reaches full travel when the ecu is still commanding steps then the position is lost until it can be re-homed.

So I suspect for a device such as an EGR valve that would likely have to fully close against a stop, there would have to be some strategy to regularly reset the home position. Assuming it was originally commanded to variable positions and not just fully opened/closed, then original Toyota strategy was probably designed more specifically for this type of application - possibly something like zero's the step count every time the valve is fully closed or there maybe electrical methods such as current or emf monitoring to indicate it needs the position reset.

If it were a common enough request we would look at adding a new function to do it but I think you are the first I have ever seen ask for it.

Is there no way to replace it with something like a Bosch idle valve?

Hi Adam thanks for the explanation. Please don't take my previous response as me knock Links's system. As a novice who messes on with these things as a hobby I always assume there's a simple way around what I'm trying to achieve, I just don't know it ha ha. In this case may be my efforts to try and upgrade the egr on my car are looking a lot more complex than I originally thought. The reason I went with a yaris egr valve was the mounting face to the inlet was compatible and the egr cooler that attaches to it runs, down the side of the head relatively neatly.

I wouldn't expect Link to specifically work on software for this. Like I said before I isually just assume I'm missing something because i don't know fully how the system worked. I was slightly confused when setting up the stepper in the Link software when it gave me the option to not choose a feedback channel. I assumed that would make it work it some form of open look mode. That was a couple days of head scratching as to why I couldn't get any movement out of the valve ha ha.

I do still have the original egr system which is vacuum operated but replacement parts are getting difficult to source and emmissions checks in the UK are getting stricter every year.

Ultimately I was looking for a future proof solution to a problem that isn't yet a problem, that may have to go on the back burner for a while.