Doug D said:What year is your vehicle? 2011 I have a 2006 Ram 1500 QC SB 4x2 with the 5.7L Hemi, 545RFE transmission and 3.55 gears and unless I have a heavy load it's rare for the transmission to downshift on long hills at interstate speeds (65-70 mph). I don't have an aftermarket device such that you have so I have to depend on my "ears" to hear any "knocking". Though I will say the DS Trinity does sound sort of neat with real time monitoring. All PCM outputs on the bus can be converted to a gauge to watch, 4 at a time, after that it's too small to see.
The most common problem with regards to the 5.7L Hemi I've read on other forums is the infamous Hemi "tick". Cold start Some have it, some don't.
Is the knock just during the transition from MDS to normal operation (all 8 cylinders) or does it continue to "knock" in full V8 mode? Yes and no knock in V8 mode If it's short term, it may just be the nature of the beast.
Agree with Dave in that it could have been mislabeled or bad fuel. I haven't had any "fuel" issues, but do know a friend who's Tahoe runs poorly if fed anything other than Exxon fuel. Or so she claims.