How exactly does EGR work?

[dye_kapp]

How does pumping hot air from the exhaust into a hot intake reduce combustion chamber temperatures more than sucking cool air into a hot intake?

I don't see how hot exhaust=cool NOx

I failed smog on NOx in California if you didn't pick that part up...

 

[Skitter302]

Allow me to quote the internet and give ya the breakdown,

When combustion temperatures exceed 2500°F, atmospheric nitrogen begins to react with oxygen during combustion. The result is various compounds called nitrogen oxides (NOX), which play a major role in "urban air pollution." 

To Limit NOX carbon (your exhaust) is recycled back into the engine limiting how much O2 is in the combustion process. Less O2 being combusted = Temperatures below 2500°F = low to no NOX. The EGR valve controls a small passageway between the intake and exhaust manifolds. When the valve opens, intake vacuum draws exhaust through the valve. This dilutes the incoming air/fuel mixture and has a quenching effect on combustion temperatures which keeps NOX within "acceptable limits".
 

If the EGR is malfunctioning (staying open or closed) most the time it is caused by carbon buildup. The fix? Remove the valve and used carb cleaner to remove the Carbon deposits.

 

[dye_kapp]

So all engines naturally run lean, so the EGR richens the mixture by displacing oxygen, and the fuel itself cools the combustion temp?

A wire ripped out of the egr solenoid connector...

 

[Skitter302]

I think your off a lil' still, its the science of using recycled exhaust gas to change how efficient the burn is during combustion.

And since your wire is out of the connecter I would look into getting that fixed to pass emissions. We don't have emissions testing where I live so I don't have any tips to help ya pass except for, fix whats broke.