Originally Posted by chadg2
How did you get your DEF gauge to go back to where it was before you swapped the ECU to Hot Tune? Mine won't go back to 50%.
I'm guessing the DEF gauge is about as much of a lie as the temp gauge is on most vehicles (read: an "I did not have sexual relations with that woman, Miss Lewinsky."-class lie).
Remember, the DEF fill gauge is based on a highly insensitive ultrasonic system. Recall the caution that we must add at least one gallon whenever we add *any* DEF, otherwise the system might not sense it? Yeah, I would not be surprised if our DEF gauge is based on some dubious ultrasonic reading followed by "dead reckoning" where the computer subtracts based on how much it believes it probably pumped out/consumed. Such a scenario could be consistent with your ECU swap observations (i.e. perhaps the old computer had some subtracted offset from the ultrasonic reading that the new PCM does not). Personally, I wouldn't sweat about the DEF gauge.
The CC variation you report *would* bother me. I have experienced that on my stock Jeep once: wide open level road, ACC, and it kept decelerating ~10 mph, downshifting a gear or two, hard accelerating back to the limit, coasting back down ~10 mph...