Fast69Mopar
Senior Member
I dealt with this exact issue a few weeks ago with my Dad's 2016 Ram 1500 5.7. I didn't have my tuning laptop with me that has an older version of HP Tuners VCM Suite. I had my daily driver laptop with me that has the latest beta version of the VCM Suite. I need to get my Dad's truck ready for a state inspection here in Texas and I couldn't change the tune so I had to do what you are doing now. After trying to double stack the non-foulers and packing them with steel wool I had to go with three non-foulers per side to get the voltage right on the downstream oxygen sensors. With the latest version of HP Tuners you cannot turn off the downstream oxygen sensors so that was my limiting factor in the tune. Finally, after stacking three non-foulers per side no was able to get the voltage down to 0.488V on the downstream sensors.Ok, I spoke too soon. It threw Running Rich codes on the way home. I'm gonna stuff more steel wool into the downstream sensor adapters. But no Surging RPMs still. I'm gonna let it cool off and attack it tonight if it doesn't rain.
If you had a scan tool you could monitor the voltage on your downstream oxygen sensors and see just how high the voltage is that is giving you the rich DTC's. It doesn't take much over 0.565V for the PCM to detect a rich condition and set a corresponding DTC.
Since you may not have a scan tool handy or HP Tuners I would put another non-fouler per side just to see what happens. Don't drill out the holes either. Place the 3rd one directly on the O2 **** on each side.