Originally Posted by knightmare1015
X2. That EGR aint something to play with at all. Whom ever invented it should be taken out back somewhere and shot. Your truck will go in "limp mode" and it sucks when it does. Basically limp mode is where your truck struggles to move at ANY speed and your check engine light lights up like a christmas tree. That's if you're lucky to. Most people say that if the EGR takes a dump then that's where you sit.
It doesn't really have any remarkable disadvantages and to say its something awful that the inventor of which should be shot is ridiculous.
Would the engine make more power without an EGR system all together, yes. Introducing exhaust gas does reduce the concentration of oxygen an therefore reduce power. However, in doing so it is also keeping the cylinder head and exhaust valve temperatures down where they need to be and removes quite a bit of nitrous oxide from the exhaust. You may not care about the exhaust gasses but you probably would care about the cylinder heads and valves burning up.
The check engine light will come on with a fault requiring it do so. It does not act like a christmas tree. It will just come on. If the computer detects ANY condition that can damage components of the engine or transmission, it will go into limp mode. Limp mode will restrict RPM to prevent you from causing damage. It does not cause you to struggle to move at any speed or force you to not move at all. Its just an RPM limiter with some other internal fuel and air adjustments.
If the EGR is stuck closed, the cylinder heads and valves can burn, hence why it goes into limp mode. Its protecting itself. If the valve is stuck wide open, it will cause starting and idling problems because it would normally be closed or reduced. The severity of these problems varies with how open it is, the weather conditions, engine temperature at the time, and what you're doing. Most people don't say the EGR takes a dump and that's where you sit. That is purely dramatic exaggeration.
Since the EGR system is supervised by the computer and controlled by the computer, you can not simply block it off without tripping trouble conditions. Way back in the day when the computer didn't regulate or supervise it, you could get away with that. But not anymore.