Well, in a word, yes. First of all it’s the nature of the beast—in the sheer number of pollutants that must be reduced, eliminated or contained that are part of diesel exhaust. Secondly, these clean diesel exhaust emission controls require a sophisticated set of control devices: high pressure common rail fuel systems with precision quick acting injectors … exhaust gas recirculating devices … exhaust oxidation catalysts … and particulate matter filters.
Not only do these devices have to work properly when designed and tested individually, they must also all work together—with none adversely affecting the performance of another. And most importantly, these devices must continue to function under real world use conditions for a prescribed number of miles and years as set forth by the vehicle’s particular bin certification level.
Further complicating matters for diesel engine manufacturers is the amount of time consumed by the certification process—it is a documentation heavy procedure that requires a lot of record keeping and review. And precious time can be lost if any one component fails certification. Component failure often requires a redesign of the offending piece--and restarting, from the beginning, the entire process.
What is Ultra Low Sulfur Diesel (ULSD)?
What exactly is in that diesel exhaust?
How are diesel emissions measured and regulated?