EGR stepper position vs ? to determine if EGR cooler is clogged...

So playing around with some of the parameters I can see in Torque Pro, I came across the EGR valve stepper position. I have noticed that once the car is warmed up, it kinda sorta maybe correlates to the eco side of the Hybrid System Indicator screen. The EGR valve is closed right at the left side of the ECO are on the display, and is open fully as the display approaches the right side but a bit before we get into the PWR area. I am sure it is operating by some complex parameter based on temperatures, O2 sensor feedback, and throttle position and not some simple single parameter, but it got me to wondering.
If we can correlate the EGR stepper position to some other driving variable (maybe it is an O2 sensor in the exhaust) , could we diagnose a clogged EGR cooler before a code is thrown based on the computer demanding a LOT of EGR valve opening because it is not getting much through the cooler? Any techstream savy people ever ponder on this one?

I also thought the EGR stepper had something like 111 positions, but i have never seen mine go above 72 under any driving conditions. (2012 model 4).

Thanks for any comments. Kinda new at the Prius thing, but am having fun with the technology available to explore it.

 

Doesnt hit the original question, but my car also seems to have a buzz in the passenger dash somewhere at certain engine revs or at certain textures of roads. I am not sure I am ready to try and track down a noise, but at the right frequency of either engine or road texture, it gets moderately loud. the way the stepper motor works I don't think you would be hearing a buzz, it seems to be more of a multi-turn screw drive to actuate the valve.

 

Well, I just need to know what data points to track. I JUST cleaned the EGR cooler and pipe two weeks ago. Have not done the intake cover yet, but I understand it is a cakewalk compared to the cooler.

 

Will move to the other thread if I have anything else, but my understanding of the head gasket problem is the "almost" delete of the cooler where it shoots some 1200 degree not-very-cooled air into the intake, and the ridiculous net intake temperature causes dieseling, and BOOM, no more head gasket. If it were totally blanked off I don't think we would see the gasket in jeopardy. If you wanted to do a delete, all it would take is making a "blank" for one of the gaskets. Not that I am recommending that, but I suspect the headgasket would be happier compared to an almost blocked cooler.

If a moderator thinks this should be merged into the existing topic, I am totally onboard with that.

 

Cannot really tell much from that. I have watched the stepper motor positioning on the Torque app, and 1) the EGR does not open until up to temperature (around 155-160 degrees engine coolant temp) and 2) you need to be cruising down the road with the bar at least getting into the ECO zone before it opens. My EGR valve is pretty much fully open before I get the bar into the CHG zone. A rough idle might indicate an EGR valve that is at least partially stuck open.

 

Should add that just removing the stepper motor assembly, I am not sure that would force the EGR valve closed and smooth out the idle as you seem to be describing.