Attention: TDR Forum Junkies 
CR is short for common rail, just an easier way to denote what engine.
Limp mode is both, a mode the engine defaults to and a general condition of "something ain't right". The ECU will shut down a cylinder if it sees the coil resistance go high, if shorts completely to no resistance it shuts down the whole bank. Other conditions will cause the engine to derate power levels, it is all limp mode when you just limp into the nearest stopping point no matter what caused it.
Internal tolerances of a CR injector are on the order of 2 microns, it is under tremendous pressures up to 23k psi, and one the average it operates 2 to 2.5 times more often than a 12V injector in the same mileage. The fact that the average life expectancy for a CR injector increased slightly over a 12V injector puts the cost and wear thing into a bit more perspective. Yes, they cost more because they perform better over the same or longer time periods as older units. Also, the 2 um is easier to understand when compared to a human hair at 40 to 120 microns, it doesn't take much to foul up tight tolerances. At extremely high pressures and the heat cycles metal tends to act differently than at ambient temp, it does not take much to gall and score the internals to severely impact operation. The whole injector is cooled by diesel also, the coils have a heat sink that is exposed to the fuel to help keep heat cycling in check. Unfortunately water and solids in the fuel have a large impact on all parts of the injector, erode and corrode. ANY small imperfection or casting on a heat sink allows uneven cooling and even seeping fuel into the wingdings along with the constant heat cycling.
When you really think about the conditions a CR injector is really subject too and how critical setup and manufacturing is the perspective changes somewhat, they are not rocket science caliber but pretty darn close. Also one reason why remans are such a crap shoot, both for longevity and assembly tolerances. The price difference between a reman and NEW injector is minimal in the big picture.
Limp mode is both, a mode the engine defaults to and a general condition of "something ain't right". The ECU will shut down a cylinder if it sees the coil resistance go high, if shorts completely to no resistance it shuts down the whole bank. Other conditions will cause the engine to derate power levels, it is all limp mode when you just limp into the nearest stopping point no matter what caused it.
Internal tolerances of a CR injector are on the order of 2 microns, it is under tremendous pressures up to 23k psi, and one the average it operates 2 to 2.5 times more often than a 12V injector in the same mileage. The fact that the average life expectancy for a CR injector increased slightly over a 12V injector puts the cost and wear thing into a bit more perspective. Yes, they cost more because they perform better over the same or longer time periods as older units. Also, the 2 um is easier to understand when compared to a human hair at 40 to 120 microns, it doesn't take much to foul up tight tolerances. At extremely high pressures and the heat cycles metal tends to act differently than at ambient temp, it does not take much to gall and score the internals to severely impact operation. The whole injector is cooled by diesel also, the coils have a heat sink that is exposed to the fuel to help keep heat cycling in check. Unfortunately water and solids in the fuel have a large impact on all parts of the injector, erode and corrode. ANY small imperfection or casting on a heat sink allows uneven cooling and even seeping fuel into the wingdings along with the constant heat cycling.
When you really think about the conditions a CR injector is really subject too and how critical setup and manufacturing is the perspective changes somewhat, they are not rocket science caliber but pretty darn close. Also one reason why remans are such a crap shoot, both for longevity and assembly tolerances. The price difference between a reman and NEW injector is minimal in the big picture.
