TalkingHead
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The EGR system's purpose is to control oxides of nitrogen which are formed during the peak combustion temperatures.
The end products of combustion are relatively inert gases derived from the exhaust gases which are directed into the EGR valve to help lower peak combustion temperatures.
The negative backpressure EGR valve has bleed valve spring below the diaphragm, and the valve is normally closed.
The valve varies the amount of exhaust flow into the manifold depending on manifold vacuum and variations in exhaust backpressure.
The diaphragm on this valve has an internal air bleed hole which is held closed by a small spring when there is no exhaust backpressure.
Engine vacuum opens the EGR valve against the pressure of a large spring.
When manifold vacuum combines with negative exhaust backpressure, the vacuum bleed hole opens and the EGR valve closes.
This valve will open if vacuum is applied with the engine not running.
So as it has been said repeatedly, the function of the EGR is to reduce NOx by lowering combustion temps. The EGR valve does NOT do anything else to improve efficiency or anything other than lower emissions. As long as the EEPROM has been tuned to eliminate the EGR, there will be no problems with removing it, nor will there be any change in "efficiency". I removed mine years and years ago. Also worth noting, my mileage didn't change one iota. I removed mine for a couple reasons. They're stupidly expensive to replace when they're faulty. And, The amount of carbon that the EGR valve puts in your engine is ridiculous. I rebuilt my 454 from my 1 ton about 4 or 5 years ago and the amount of sludgy carbon crap that was in the engine was unreal. The engine didn't smoke, leak oil or otherwise do anything it really shouldn't, all the carbon buildup was from years of running the EGR valve. I've rebuilt similar engines with similar miles that were older blocks that never ran an EGR and even the older engines were cleaner than my 454 TBI which was equipped with an EGR.
The only way that an engine W/ an EGR would run better or more efficiently than an engine W/O an EGR would be if someone was too lazy or ignorant to tune the ECM to reflect the removal of the EGR. If you just remove the EGR and change nothing else, then, yeah, there will be a noticeable change in fuel mileage.
The end products of combustion are relatively inert gases derived from the exhaust gases which are directed into the EGR valve to help lower peak combustion temperatures.
The negative backpressure EGR valve has bleed valve spring below the diaphragm, and the valve is normally closed.
The valve varies the amount of exhaust flow into the manifold depending on manifold vacuum and variations in exhaust backpressure.
The diaphragm on this valve has an internal air bleed hole which is held closed by a small spring when there is no exhaust backpressure.
Engine vacuum opens the EGR valve against the pressure of a large spring.
When manifold vacuum combines with negative exhaust backpressure, the vacuum bleed hole opens and the EGR valve closes.
This valve will open if vacuum is applied with the engine not running.
So as it has been said repeatedly, the function of the EGR is to reduce NOx by lowering combustion temps. The EGR valve does NOT do anything else to improve efficiency or anything other than lower emissions. As long as the EEPROM has been tuned to eliminate the EGR, there will be no problems with removing it, nor will there be any change in "efficiency". I removed mine years and years ago. Also worth noting, my mileage didn't change one iota. I removed mine for a couple reasons. They're stupidly expensive to replace when they're faulty. And, The amount of carbon that the EGR valve puts in your engine is ridiculous. I rebuilt my 454 from my 1 ton about 4 or 5 years ago and the amount of sludgy carbon crap that was in the engine was unreal. The engine didn't smoke, leak oil or otherwise do anything it really shouldn't, all the carbon buildup was from years of running the EGR valve. I've rebuilt similar engines with similar miles that were older blocks that never ran an EGR and even the older engines were cleaner than my 454 TBI which was equipped with an EGR.
The only way that an engine W/ an EGR would run better or more efficiently than an engine W/O an EGR would be if someone was too lazy or ignorant to tune the ECM to reflect the removal of the EGR. If you just remove the EGR and change nothing else, then, yeah, there will be a noticeable change in fuel mileage.
