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What's Driving You Crazy: Is it legal for diesel trucks to get tricked out to 'roll coal'?

How are these modified trucks AirCare certified before getting plates?
Screenshot 2021-11-16 045236.jpg
Posted at 4:53 AM, Nov 16, 2021
and last updated 2021-11-16 07:28:14-05

Pete from Boulder writes, “I am curious how it is legal for diesel pickup trucks to get tricked out to “roll coal” given you need to be Air Care certified before getting license plates. Seems like a waste to me if they can’t stop this type of emissions. The trucks contribute to our ozone days and it’s not fun to be at a red light when the light turns green and the black cloud envelopes everyone, especially those walking or on a bike.”

I too have been the victim of rolling coal in the past. I won’t speculate about the state of mind of the truck owners who modify their truck in this way, but the ones who talked to me about this question gave me several reasons why. Reasons like, “We just like the way it looks and like to see who can make the biggest plume. We think climate change is crap and we like to annoy the people who drive green cars. I get better power out of the engine. We don’t like when bike riders take up the whole road. We are protesting killing off oil jobs. We like having control over our own trucks and we like doing something not everyone else can do.”

None of the truck owners I spoke with wanted to be identified for this story.

Let’s look at what rolling coal is. It’s basically modifying a newer diesel engine to force more fuel into the engine than the engine can handle. That process sends a huge plume of thick, black exhaust containing unburnt fuel into the air. Many older diesel truck engines made under older air quality standards can roll coal without modifications. Rolling coal became illegal in Colorado in 2017, however, the legislature only made the act of rolling coal itself illegal — not the act of altering your vehicle.

“So, in other words, you could get busted if you unleashed your toxic fumes on someone, but not for making your vehicle able to do it,” said Danny Katz, executive director CoPIRG. “I believe there was a proposed effort in 2021 legislative session to upstream this legislation and make it illegal to alter a vehicle or knowingly sell an altered vehicle, but questions arose around who would be responsible, and I don't think it was ever drafted or introduced.”

There are several ways to modify a diesel truck to roll coal. One of the most convenient ways is to use a defeat device like a “delete tuner” or “delete kit.” They easily hook up to the OBD2 port in the truck and then, with just the press of a button, the driver can change many of the factory engine settings including the fuel mixture into the engine creating the black smoke. The same device can just as easily change the settings back to factory emissions if the driver needed the truck to pass Colorado’s AirCare emissions standards.

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“Yes, diesel owners could modify their vehicles multiple times if they wanted to invest the time, energy and money in an activity that provides no benefit,” says Dana TePoel, owner of Lake Arbor Auto in Westminster. “It seems illogical to us, but we suppose it could happen.”

In an emission report released late last year, the United States Environmental Protection Agency estimates about 15% of diesel trucks in the United States with original certified emissions have had those emissions systems tampered with. The EPA Office of Enforcement and Compliance Assurance says tampering with vehicle emissions controls or using an aftermarket defeat device remains illegal. The EPA says these defeat devices bypass or otherwise render inoperative required emissions control systems, resulting in significant increases in harmful air emissions.

“A truck fails here about three times a week,” TePoel said. “The older vehicles usually fail due to high opacity (thick smoke). The new ones usually fail due to missing or altered components; and quite often those components are missing or altered because of previous owners.”

The EPA has gone after several major makers of tuners recently, including penalizing Premier Performance $3 million earlier this year for selling "defeat" devices. The EPA actions have stopped companies that make tuners from being publicly advertised but there are still tuners that exist that will allow diesel owners to roll coal.

There are more invasive ways to change the engine as well. According to the website Truck of Mine, another way to modify a diesel truck to roll coal is by aggressively custom-tuning the truck and installing bigger injectors. Injectors pump large amounts of fuel into the engine during each injection cycle, while the tuning fools your engine into wanting more fuel.

According to Colorado’s Department of Public Health and Environment, an officer may stop a vehicle with excessive exhaust, either gas or diesel, issue a ticket, and order the owner to make repairs. Colorado law provides for a $100 fine for violating the Nuisance Exhibition of Motor Vehicle Exhaust law. Some jurisdictions can impose additional fines for operating a smoking vehicle.

“We believe the diesel emissions program in Colorado has had a significant net benefit to the state’s clean air, and we surely wouldn’t want to see anybody reverse our clean-air progress with a campaign to disassemble the emissions program,” TePoel says. “That would be like eliminating all traffic signals just because there are a few drivers who run red lights.”

There is also the Smoking Vehicle Hotline program in Colorado that helps identify any vehicle with excessive emissions, and gives owners of those vehicles information that will encourage them to voluntarily make needed repairs.

Denver7 traffic anchor Jayson Luber says he has been covering Denver-metro traffic since Ben-Hur was driving a chariot. (We believe the actual number is over 25 years.) He's obsessed with letting viewers know what's happening on their drive and the best way to avoid the problems that spring up. Follow him on Facebook, Twitter or Instagram or listen to his Driving You Crazy podcast on iTunes , Stitcher , Google Play or Podbean.