What Makes Modification Emissions Legal?
As most readers are probably aware, the aftermarket has worked with CARB to design an approval process for California street-legal, emissions-compliant components. If an installed component doesn't negatively affect the vehicle's emissions, it may be granted a CARB executive order. However, since 2001 there's been a disconnect in the ability of the aftermarket to get diesel performance products approved and get an executive order issued because CARB simply hasn't been awarding them.
In talking with the staff at Banks Engineering, they said that as far as they understand it, CARB is developing a new form of tests that would more properly capture the emissions of diesel engines. So what it comes down to is that since there is no test procedure for diesel in place right now, CARB is very wary of giving diesel products an executive order. Until this test regimen is implemented, the aftermarket companies are sort of in limbo, as is the diesel performance enthusiast.
For aftermarket firms, this becomes a very gray area in terms of aftermarket sales of emissions-legal products for diesel engines. You have to keep in mind that the facts are time sensitive, and as soon as CARB announces its test regimen, whatever we say here will probably have to be amended.
Diesel Emissions Equipment-Today
Diesel catalytic converters were introduced in the mid 1990s, and exhaust gas recirculation (EGR) systems started showing up on most diesels introduced in the late 1990s. Presently, those are the only emissions systems that are required to make the engine run.
Currently, we're not aware of any states that are "sniffing" the exhaust of diesel engines to check emissions compliance for hydrocarbons, nitrogen oxides, and carbon monoxide. There are a few with visual inspections to check that required components-such as the catalytic converter and EGR-are installed and working properly, as well as a few that run opacity tests to verify soot levels.
Part of the reason for this lax enforcement effort is that the equipment to conduct a diesel vehicle emissions test is very expensive, and the program would be very costly. As the CARB source told us, the diesel fleet is such a small percentage that the agency believes that the effort wouldn't be cost effective. However, the source also said that in California the Bureau of Automotive Repair runs the inspection programs, and any future program would originate from that agency.