well, how can I answer this and still be politically correct? I hate to use the word "problems". The early injectors used a metal on the needle and seat that were prone to pitting at the extreme pressures coupled with dirt-etc. In mid year 02, they were changed to a hardened needle and seat which extends the life considerably of the injector. In mid model year 04, the engine has been redesigned to contain different injectors mounted external to the engine, this mandates change in the fuel plumbing and head and valve cover design, they have also added some emission control devices to the engine to meet 06 standards. Fortunatly, its not in vain as they also bumped the power to 320 hp and 565tq.