...function of the egr valve? Can it be repaired or...

Answer by Tom L
Submitted on 12/20/2003
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EGR Theory. EGR serves one purpose and one purpose only. That purpose is to reduce Oxides of Nitrogen (NOx). Undernormal combustion, Nitrogen(N2)Oxygen (O2) in the air and Hydrocarbons (HC) in the fuel combind into water(H2O) Carbon dioxide (CO2) and the Nitrogen remains unchanged. Under very hot combustion temperatures, the Nitrogen reacts with the other two byproducts and forms Nitrogen oxide (NO). After being released into the atmosphere, it picks up another Oxygen and becomes Nitrogen dioxide (NO2). In the presence of sunlight, it combines with other compounds like Hydrocarbons and forms Smog. Since exhaust gas is inert (very stable) it doesn’t burn again. So by being introduced into the combustion chamber, it will lower combustion chamber temps enough so that the Nitrogen doesn’t react with the other compounds and is passed unchanged out the tailpipe thus not contributing to smog. Now, since exhaust gas doesn’t burn, it doesn’t exactly help with combustion. At higher RPM’s, this really isn’t noticable, but at idle, the reintroduction of exhaust gas will cause a very rough idle and can cause stalling if to much is introduced into the combustion chamber

Answer by DirtyTbird
Submitted on 5/25/2004
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People, people, people, stop worrying. I drive a 92 ford tbird, and it runs great the only problem is that the check engine light comes on randomly. When that happens chances are its a egr problem or an 02 problem. Leaving your EGR (if it is what is the problem) wont do anything and is absolutely NO threat to your vehicle at all. Just good luck with an emissions test here in Ontario. They cost around 100 bucks Canadian (installed) thats what ford will quote. The only thing is the random check engine light which is annoying. If you are really bothered by it go to walmart, and rent (buy it then return it right after) a code checker, for your make of vehicle. It will confirm that it is an egr problem or whatever the problem may be. Either way if its egr its not worth the money having it repaired, try cleaning it as the process is described above.

Answer by memyselfandi
Submitted on 6/13/2004
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hey i have a 90 olds cutlass supreme with the 3.1 v6. it has been acting up on several different occasions. it doesn't do it all the time but will mainly when i first start it up. it idles fine but when i press the gas it wants to stall or quit. it will do this in park or any gear. it kinda smells out the tail pipe too. i was told it could be the map sensor or the egr valve. i replaced the map sensor but with no resolve. then somebody told me to clean the egr valve out. i removed it & there is like 3 parts to it. i cleaned all the black carbon & crap off these parts & put it back together. it seems to run good now, but still kinda smelly. i might pick up one at the junk yard. any ideas?? memyselfandi988@hotmail.com

Answer by Duston
Submitted on 6/30/2004
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I own a 94 Chevy Blazer 4.3 V6, and I've taken it across the country with the EGR going out on me only twice. Now it goes out anytime I take it out of town, or even in town. I've gotten to the point where I can pull it off myself, remove the tiny chip of carbon and put it back on. I've talked to mechanics and I've had the engine blown out to hopefully clear the carbon but it's really pointless, the problem remains. So in the end it's not the EGR valve that is the problem you could throw it against a brick wall and it wont break or damage your engine, it's the carbon that gets lodged in it. At least thats the story in the 4.3 Vortec V6. It's a common problem in them and I think it's a ridiculous flaw that was overlooked by the manufacturer

Answer by DB
Submitted on 7/8/2004
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How EGR systems work The EGR valve recirculates exhaust into the intake stream. Exhaust gases have already combusted, so they do not burn again when they are recirculated. These gases displace some of the normal intake charge. This chemically slows and cools the combustion process by several hundred degrees, thus reducing NOx formation. The design challenge The EGR system of today must precisely control the flow of recirculated exhaust. Too much flow will retard engine performance and cause a hesitation on acceleration. Too little flow will increase NOx and cause engine ping. A well-designed system will actually increase engine performance and economy. Why? As the combustion chamber temperature is reduced, engine detonation potential is also reduced. This factor enabled the software engineers to write a more aggressive timing advance curve into the spark timing program. If the EGR valve is not flowing, onboard diagnostics (OBD) systems will set a code and the power control module (PCM) will use a backup timing curve that has less advance to prevent engine ping. Less timing advance means less performance and economy. Do your customer a favor and fix those EGR codes that you may have previously deemed as unimportant.

Answer by Dave
Submitted on 7/10/2004
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My 96 Lumina'sSES light keeps coming on. It's the EGR valve. I've cast about on the Internet, and it seems that it can cause maybe three real problems. 1. Smog--your car puts out more pollution. That is a given. If your EGR valve is faulty its almost certainly doing this. 2. It could cause some skipping on accelration or problems with idling as noted here, but probably not. 3. It is more likely that you could develop an engine knock from the air/fuel mixture becoming to hot "ping" or "detonation". If you want to drop $400-500 bucks to fix the amount of pollution your car puts out that's fine...a little weird, but fine. My EGR has been out for three months and I haven't experienced problems 2 or 3. However, I would say that 2 would be annoying, and 3 after a while would become dangerous to your engine. My advice is that if your budget is tight, wait. IT seems you could potentially drive a long while without ever developing any real problems. Hope this helps some.

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