Remove the EGR Valve – Bad for Your Diesel Engine?

In an attempt to reduce diesel exhaust pollutants, the concept of the Exhaust Gas Re-circulation (EGR) system was implemented on all diesel trucks around the year 2007, per EPA regulations. The purpose being, to reduce nitrogen oxide emissions, which contribute to air pollution. However, with the introduction of the EGR valve system on diesel engines, there has been a noticeable and documented 3% drop in engine efficiency, which means an additional 3% more diesel is consumed and burned to generate the same amount of power.

egr valveIf 3% more diesel is being burned, that means there’s also a 3% increase in all the pollutants being generated. While emission controls are clearly a good thing, it isn’t clear if the EGR valve is causing more good than harm by burning off the trace amount of nitrogen oxides by simply burning more fuel. Furthermore, it may not be good for the the diesel engine itself.

Looking as the image to the left, the process is as follows: As the diesel fuel is mixed with the incoming air, the mixture is burned in the combustion chambers of the engine. Most of the exhaust is expelled out the tailpipe of the vehicle. However, diesel engines equipped with the EGR system divert some of the exhaust off the manifold, re-mix it with fuel and incoming air so that it can be re-burned. While this does help reduce the oxide pollutants a small amount, it has negative side affects on the diesel engine itself.

The first of which is, slightly worse fuel economy. Exhaust gases don’t re-burn all that well because it contains very little that is “useful” to the combustion process. So when you reintroduce exhaust back into the diesel engine, you are displacing fresh air that has more oxygen with exhaust gasses that don’t. As a result, the engine doesn’t burn the fuel as well because there is less oxygen.

Second, diesel exhaust by its very nature has pollutants in it, including soot in the form of carbon. By re-introducing the untreated exhaust back into the combustion chamber, soot will start to buildup in the oil and on other internal engine parts, including the intake turbo. This cannot be good, but it’s debatable how bad it is. I’m of the opinion that the cleaner the air going into the engine, the better it will run and the less problems you’ll have in the long run. This is the whole reason why vehicles have air filters. The EGR system does not pass the exhaust back through the air filter because there is too much soot which would clog the air filter in a matter of minutes. So if the EGR process is too dirty to pass the exhaust through a filter, think of all that black soot that is going directly into the engine.

Third, because exhaust is hot, it must first be cooled prior to re-mixing it with new air. Piping 700°F gasses into the engine is a recipe for disaster. Therefore, an EGR cooler is needed. It is basically a second radiator that reduces the exhaust gas temperatures before they are re-burned. If the cooler fails, the temperatures in the engine can skyrocket quickly causing permanent damage.

Is the EGR valve needed? The answer is no, if you don’t mind breaking the law. Federal emission laws state you are not allowed to tamper with the emission control system on a vehicle, which the EGR is a part of. And since EPA regulations require it, you cannot remove it. If caught, you could face a penalty. However, the EGR provides no benefit to the diesel engine and can be “removed” with no ill affects. In fact, many have reported that their diesel engine runs better with it removed. On the dodge Ram forums, quite a few people reported improved gas mileage with a 1 to 2 mpg increase in fuel efficiency once the EGR system has been disabled or removed. Some also report a little better response in acceleration. Almost all said their oil was in much better condition when they changed it.

How hard is it to remove the EGR? Well, that depends on how you want to remove it.

The first option is simple. Simply turn off the truck and disconnect the EGR plug from the butterfly valve. This takes about 15 seconds. It’s important the truck is turned off when disconnecting the cable because the butterfly value is in the closed position during this time (meaning, exhaust gasses are blocked from re-entering the engine). When the engine is on, the valve opens and closes as needed based on the inputs sent from the on-board computer. However, exiting exhaust pressures on the the butterfly valve may cause it to open slightly, which may continually allow exhaust gasses into the engine. Therefore a complete removal of the EGR is the second option.

An EGR Delete Kit can be purchased from just about any online performance parts shop (Google “egr delete kit“). This physically removes the butterfly value, the hose, and blocks off the incoming ports where the EGR cross-over exhaust return pipe directs the exhaust back into the intake turbo for re-mixing with outside air. Because the exhaust gas return port is completely blocked off, no exhaust gasses re-enter the engine. There is also the option of performing an EGR cooler delete as well, but this will just remove the cooler, which is now being bypassed.

Keep in mind, that any of the options above will cause a soft engine light to come on (soft meaning, it doesn’t affect your truck). This is completely normal and just indicates that there is a “problem” with the EGR system. It does not put the truck in “limp mode”. As a result, the computer tells the truck to operate as if there is no EGR (which there isn’t for all intents and purposes). Some report the engine sounds a little different once the EGR valve is removed.

With the EGR valve removed, your truck will run a lot cooler and will take longer to heat up, especially in colder climates. This is why you see a lot of diesel truck owners block off their radiators with cardboard or other shielding to stop the cold air from cooling the truck down. Diesels need to run a little hot to be fuel efficient. They don’t like to be cold.

But please remember, it is illegal to remove the EGR valve from your vehicle. A vehicle emissions testing center can report your violation, not to mention you won’t pass the test.

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