I've noticed that when driving 40+ mph, if I quickly let off the throttle, the ultra guage shows an open loop condition until I come to a stop or apply the throttle again. Is this normal?

 

Yup. Mine does the same.

 

Time to borrow some ones real time scanner and verify if this is happening, if it is, you have a problem cause once your engine clear around 120 to 140 degrees, you are in closed loop and should not go back to open loop.

 

oh no, mine does the same thing too. But then again, it happens with my VW Passat, so maybe I have two problems, or maybe the problem is the Ultraguage....

 

Mine does it too. I'm just thinking a little excess fuel or something, I'm not worried about it

 

It goes into open loop because at that point you are engine breaking and its cut off the injectors hence its ignoring O2 sensors hence why its in open loop

Mine does the same thing but also shows 999 MPG on the instantaneous reading.

 

Same here, I thought this was normal.

 

Speaking of UG, I wish we could get actual MPG on the Ultras with our trucks..

 

Mine goes to open loop when under wide open throttle, which from what I have read is normal.

 

WIDE OPEN THROTTLE