As with sorry driving habits and non-automotive silicone procedures, truck news migrates eastward from California, which began a diesel emissions testing program January 1, 2010. Diesel testing already exists in some regions, but whether or not it’s done properly, many states will follow California’s lead.
Of California’s roughly 25 million road-registered vehicles, a bit more than a half-million (or about two percent) are diesels built after 1997; exact figures
are elusive because even my police buddies say the motor vehicle department is six months behind. And while California has said a third of all CO2 produced in the state comes from gasoline vehicles, it has implemented emissions testing for this two percent of the vehicle population (1998 and newer, greater than 14,000-pound GVWR). For the record, nothing in my fleet qualifies.
This group may include a diesel of yours: F-250 and F-350, all Duramax pickups, Dodge/Ram Cummins, Jeep Liberty and Grand Cherokee, Mercedes, Audi, BMW, VW, and Sprinter. And just as diesel gets stricter out-of-compliance constraints than gasoline, diesels are not exempted for the first four to six years as gasoline engines are. Hybrids are also currently exempted from testing, despite some hybrid trucks being no cleaner than many non-hybrids, according to government window stickers.
If you want to blame someone, pick any recent tuned-diesel owner who delights in smoking his truck away from a stop sign. I’m okay with annual vehicle emissions testing, although California puts the onus on individuals who can’t resist, as opposed to big corporations or alliances that can. Emissions from diesel engines have dropped by a factor of approximately 100 in 20 years, and gasoline engines emissions have also dropped substantially; but overall air quality in California has not improved similarly, and no other pollution source has made such advances.
In the infancy of smog testing, I owned one car that got 18 percent better mpg and lower CO and HC with the catalyst removed than with it on, but saving fuel and lower emissions didn’t count like a technician seeing a catalyst. At the time, the state manual that listed that car’s required equipment was wrong. And beyond revenue generation, that’s a big problem with the new emissions test: It’s an essay-question test (subjective) when it should be true/false or matching (objective).
The responsible bureaus made videos to show prospective smog-test station principals what will be required. The videos are full of out-of-touch statements, such as, “Most of the diesels have turbos,” and show an “illegally modified vehicle that would pass the tailpipe but fail the visual.” With a subjective test, minor issues could become a big problem if those instructing the testers can’t get it right.
California’s test is three parts. First, there is a visual check for unapproved (no CARB Exemption Order number -- E.O.) additions or changes. Exhaust brakes, added filters and water separators, air cleaners, air horn intakes, and cat/DPF-back exhausts won’t need an E.O., but any chip/module/tuner and added injection (propane, nitrous, methanol, hydrogen) will.
For intakes, turbos, intercoolers, injectors, and injection pumps, the part has to be direct replacement or have an E.O. number. Those E.O. numbers are expensive to get, so few parts have them now. There isn’t an EGR function test, but an EGR is required, as is the intake manifold grid heater on a Cummins (the last test I saw showed removing it cost power on a 450-plus-horsepower truck). No mention is made of show parts or components that have been coated for heat or corrosion protection, yet these otherwise-standard parts are sure to confuse some smog techs.
Next, there’s the OBD-II test, which is essentially a bulb check to verify the system functions. Any bulb lit continuously or a diagnostic or error code will cause a problem, and we all know about idling diesels that throw lights because DPF regen is due, but that won’t happen while the vehicle is parked.
The final part is the tailpipe smoke test, just in case a vehicle can’t connect to OBD-II or the computer was reflashed using an aftermarket programmer. In another blow to standardization, California had an issue with SAE snap-idle test protocol and will not use it. Testers are to watch the tailpipe for 10 seconds at idle; any smoke is a failure, so make sure your truck is warm and has reasonably fresh oil.
They test three times by flooring and releasing the accelerator pedal, the first time to verify revs climb to 2000-3000 rpm (apparently some Duramax-equipped trucks require a modified pedal application -- more subjectivity). The second and third tests are to watch for smoke 10 feet from the tailpipe and three feet above the ground. Any smoke lingering beyond three seconds is deemed a failure. It doesn’t state if the three seconds is from pedal-down or pedal-released, and other rules dictate a cooling fan must be blowing at the vehicle in temperatures greater than 72 degrees F.
A friend of mine wants to cover a bone-stock truck in performance parts decals and see how long a tech looks before passing or failing the visual.
I’d just go on a windy day and hope if your state starts testing they do it properly.