According to records filed in the case, Achtemeier conspired with mechanics in garages and operators of truck fleets to disable the anti-pollution software installed on diesel trucks.
Coconspirators who wanted to disable their trucks’ pollution control hardware system—a process commonly known as “deleting”—sought Achtemeier’s help to trick the truck’s software into believing the emissions control systems were still functional, a process known as “tuning.”
Monitoring software on a deleted truck will detect that the pollution control hardware is not functioning and will prevent the truck from running. Achtemeier disabled the monitoring software on his client’s trucks by connecting to laptops he had provided to various coconspirators. Some of the coconspirators would pass the laptop on to others seeking to have the anti-pollution software disabled on their trucks. Once the laptop was hooked up to the truck’s onboard computer, Achtemeier could access it from his computer and tune the software designed to slow the truck if the pollution control device was missing or malfunctioning. Achtemeier could “tune” trucks remotely, which enabled him to maximize his environmental impact and personal profit.
If the “delete” was removing their catalytic convertor and not just reprogramming the ECU then there is a mild to moderate performance increase caused by reducing exhaust pressure. If it’s easier to push the exhaust out then there’s more power going to the wheels.
If it’s just ECU changes it’s probably related to the air/fuel mixture it’s using. Often douchebags will hack this to “roll coal” but changing this can give you increased horsepower at the expense of emissions.
As someone whose car has a tune but still passes emissions inspections, this guy is both bad at tuning cars and also an asshole.