When it comes to engines, the term "deleting" refers to the removal of one or more of the emissions control devices that the engine came with. When an emissions device is "deleted", the device and any other relevant components in question are physically removed and the engine is then re-tuned to run without said device.
"Deleting" is different from "defeating" in the sense that "deleting" refers to physically removing emissions devices, but "defeating" involves disabling emissions devices while leaving all of them in place on the engine. For example, an EGR
(exhaust gas recirculation) cooler can be defeated by welding
it shut in
some spot or blocking it off from one or both ends by inserting a metal plate between the cooler and the exhaust or intake manifold
Particulate Filters) can be defeated by being drilled
out or by installing bypass pipes.
engines, people who do deletes will typically remove EGR
(Exhaust Gas Recirculation) systems and DPF's
(Diesel Particulate Filters), as these two systems are infamous for drastically increasing a Diesel engine's
Here in Michigan we no longer have any kind of emissions testing
, which means that today you can find quite a few deleted Diesel trucks
, and even some cars and SUV's
, running around in the state.