egr what is it and what is it for

drewtori · October 9, 2006

what the egr for? do we need it i saw headers that dont need it or u can get the headers with it whats the scoop thanxs.

ZZebes · October 9, 2006

Its an emissons thing, it takes some of the exhaust gasses and puts them back into the intake for some ridiculous reason

dewfpo · October 9, 2006

Adding exhaust gases back into the cylinder reduces the temperature of the burn because there is not much oxygen in the exhaust gases and it takes the place of induction air. It is precisely metered. This reduces engine ping and Nitrous Oxides emissions.

DEWFPO

Mark_in_Tulsa · October 9, 2006

Adding exhaust gases back into the cylinder reduces the temperature of the burn because there is not much oxygen in the exhaust gases and it takes the place of induction air. It is precisely metered. This reduces engine ping and Nitrous Oxides emissions.

DEWFPO

<{POST_SNAPBACK}>

But having a clogged or bad EGR would cause it to ping, correct?

And now does one go about checking to see if it is bad?

ZZ327 · October 10, 2006

sometimes it could be blocked with carbon. Theres a rubber baffle on it. When I changed mine IT wasnt moving very easy when I pushed on it. the new one moved like pushing a key on a keyboard!

Haulin' 8.1 · October 10, 2006

LOL, I like you guys but from a professional's point of view this is funny stuff. We all have our own areas of expertise. EGR is a accromym for Exhaust Gas Recirculation. As stated it is a emmissions reduction system that recirculates engine exhaust gasses back into the intake tract. Since the oxegen has been burnt out of these gasses they are now inert and composed mostly of nitrogen. This does two things. First it artificially reduces displacement by occupying part of the charge with inert gas. So at the same charge pressure there's less air and fuel. This in turn slows combustion times and reduces peak combustion temperatures. High combustion temperatures produce Nitrogen Oxide (NOx) which is a heavy and stable smog producing molecule. (I wish it was Nitrous Oxide (N2O)) So by keeping the peak temperature down much less smog is produced. It does have to be precisely metered as to much will prevent proper or complete combustion and kill power. EGR is limited to part throttle light accelleration and cruise conditons. It is not activated during idle, or mid to full throttle conditions to prevent misfiring, weak operation, or stalling. Due to the fact that dilluted charges burn much slower than pure ones igniton timing is advanced during EGR operation to compensate for it. If you block your EGR system without reducing the igniton timing during supposed EGR operation you can easily overheat the chamber and induce detonation from the premature combustion peaking. To answer the original question you only need EGR compatible headers if your vehicle came with it and needs to retain all emmission controls to remain street legal. Otherwise it is just another thing to be dealt with and maintained. EGR equiped headers mean they have a flange to supply exhaust gasses to the factory EGR vavle. If set up properly EGR will not effect WOT power as it will be shut off. It can reduce mileage greatly if the engine is not tuned for it. It will reduce mileage in any case due to weaker combustion from any amount of charge. If EGR is removed and the engine is tuned properly it will get better mileage, though polluting more. If you can legally remove it and retune the engine control for it's abscence then the only reason to keep it would be to help the enviroment. For a hot rodder it is just another system to set up, tune around, and maintain. It boils down to what you have to do to remain legal. Cams with a lot of valve overlap produce their own "EGR" due to reversion and don't need as much help to pass the sniffer as a tight smog cam at part throttle.

I hope this is helpful,

Vernon

Edit: Dewfpo, I was just thinking about that myself and had to look it up to make sure I was using the correct terminology also.