Can someone explain how EGR works?

[Ezzo]

I'm reading all of the past threads about EGR removal. I'm trying to simplify my engine bay. My main queation that hasn't been discussed is Ive read someone saying removing it will make your engine ping more wile hot? In another thread I read the perpose of the EGR is to recirculate hot exhaust gas into the intake to keep cill temp down? Am I crazy or does this not make sence that hot gasses bring down cill temps? or am I missing a fundamental law of physics? Or is it from the unburnt fuel in the exhaust recirculating to give better atomization?

[Chukidori]

The purpose of the EGR is for emissions...

it recirculates the exhaust gasses so you can "re burn it" and remove more pollutants...at the cost of power.

I believe.

In either case, its useless to us.

[ShionS14]

the gas egr recirculates back in to the cylinder cools it down due to the ecm is measuring the airflow that is coming in and using throttle position and airflow to adjust how much fuel goes in the mix. when the exhaust gas is mixed in you are putting a gas that has most of its oxygen burned off. ofcourse you need the oxygen to burn the gas. now the ecm doesn't now how oxygen rich the air that is going in is so it mixes the fuel in based on the volume of air. when the mixture is ignited not all of the fuel is burned off due to the exhaust gas not giving much oxygen to make it a full burn. so what you have is a slight rich situation which reduces cylinder tempature and like Chukidori said it also reburns the spent gases to help reduce the harmful emissions. if it was an absolute berfect burn between the fuel (with no additives) and CO2 the end result would be pure water.

[Ezzo]

Thankyou. That was the idea I was running with but It just wasn't clicking.