I've either talked to or heard of many guys having this or similar problems with the Tier IV equipment, makes me glad I own older stuff, to be honest. I remember when "smog equipment" started happening in the 1970s, added on charcoal canisters, air pumps, etc. which did little good, robbed performance and added unneeded complexity to engines. I might be wrong about this, but the add-ons now remind me of that time, and I won't consider newer year model equipment until we have a quantum mutation in combustion and emissions control, eliminating all the hardware. To me, the only thing more frustrating that something that flat doesn't work, it something that only *kinda* works. I ran OshKosh S-series concrete mixers for many years, and on several occasions the Cummins emissions controls would take a dump and derate engines, occasionally shutting them down all together. I cannot begin to describe the horror that goes with having 10 yards of concrete on board, sometime with chemical accellerants added in winter, and hearing that engine die and that drum stop rolling. Simply because of an emissions signal that wasn't making sense to the ECU. The last time I had it happen, the truck was down for 3 weeks, we lost a $1300 load of concrete, and the repair bill was over $7500. I could turn probably 8 loads a day in that rig, at roughly $1000/load. Do the math on that fracas.