DPF Or EGR: Which One Should You Delete First?

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It's no secret that many post-2007 diesel truck owners are unhappy with the emissions equipment their trucks originally came with. Recent government mandates aimed at reducing air pollution targeted diesel-powered vehicles, resulting in the widespread adoption of diesel particulate filters and exhaust gas recirculation technology.

While these advances helped curb pollution stemming from diesel particulates, they also came at a significant cost to diesel truck owners. Many owners have reported seeing increased fuel consumption as well as reduced engine performance and an overall loss in drivability. DPF and EGR delete kits from places like Cantune are designed to restore lost performance and economy by removing the emissions equipment in question.

While most people prefer to have both systems removed at the same time, time and budget constraints may dictate a different approach. Read on to learn which deletion is worth pursuing first.

Ditching DPF First

Vehicles equipped with DPFs must undergo regenerative cycles to burn off the soot and other particles trapped within the filter. These cycles consist of a preliminary regen to preheat the DPF catalyst, which can reach temperatures of 600 degrees Fahrenheit or more, followed by a burn phase that ensures a complete conversion of soot to harmless ash.

Active DPF regeneration introduces raw fuel into the exhaust stream, either through an injection of unburnt fuel between the power and exhaust cycles of the combustion process or a direct injection into the exhaust system near the catalyst. The former creates a washdown effect in the cylinders, creating accelerated wear and tear through the washing away and dilution of engine oil.

There are plenty of compelling reasons as to why you should perform a DPF delete first. Removing the DPF will offer the most immediate benefits -- reduced exhaust temperatures and reduced back pressure due to the removal of restrictive DPF equipment. Replacing the DPF with a custom exhaust solution offers immediate gains in horsepower and overall performance, in addition to improved fuel economy. DPF removal also stops oil dilution and contamination caused by fuel washdown.

Ditching EGR First

As its namesake suggests, exhaust gas recirculation works by reintroducing small amounts of engine exhaust back into the cylinders. Adding exhaust gases back into the engine's airstream cuts the amount of oxygen available to the engine, which in turn achieves the desired goal of reducing nitrogen oxide (NOx) emissions by lowering peak cylinder temperatures.

Unfortunately for diesel engines, this often means reintroducing soot back into the engine. The resulting carbon buildup can clog up EGR valves as well as EGR coolers and intake ports, resulting in a severe reduction in power and performance. Soot buildup can even lead to severe coolant leaks and eventual engine hydro-locking. Deleting or disabling the EGR effectively blocks soot-laden exhaust gases from making an encore appearance in your engine.

In many cases, EGRs are typically less time-consuming to delete than DPFs, which require complete removal from the vehicle. Some custom diesel tunes can even disable the EGR without the need for physical removal. Disabling the EGR via software can be a time saver for those who want to start the EGR/DPF deletion process, but want to wait until a later date to finish with a complete DPF deletion.

The only problem with pursuing an EGR delete first is that you still have the DPF to contend with. You'll still have a catalyst that's progressively clogging with soot, especially if the regen functions were disabled via ECU flashing or programming. Once you have your EGR deleted or disabled, a DPF delete should be next on your to-do list.

Ultimately, it's up to you to decide whether you should delete the DPF before deleting the EGR or vice-versa.