My car runs the same with or without the egr hooked up
10-21-2004, 12:36 PM
#1
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Join Date: Dec 1999
Posts: 1,119
My car runs the same with or without the egr hooked up
The engine has been running rough at highway speeds and someone told me it could be the egr valve.
I took off the vacuum hose and it still runs exactly the same--great up to 55mph then crappy after that.
Does the egr valve even need to be hooked up because it didn't change anything at idle or on the freeway when I took off the vacuum line.
I also tested it with a vacuum pump and it holds pretty steady at aroung 6in. The reading very very slowly gets lower but I suppose that could be due to other things.
I took off the vacuum hose and it still runs exactly the same--great up to 55mph then crappy after that.
Does the egr valve even need to be hooked up because it didn't change anything at idle or on the freeway when I took off the vacuum line.
I also tested it with a vacuum pump and it holds pretty steady at aroung 6in. The reading very very slowly gets lower but I suppose that could be due to other things.
10-21-2004, 01:22 PM
#2
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Join Date: Sep 2004
Location: California
Posts: 81
Re: My car runs the same with or without the egr hooked up
The EGR's sole purpose in life is to reduce NOX emissions. NOX, or oxides of nitrogen, is the haze you see over LA, and other major cities where there is a lot of cars and industry. A few years ago, Denver had the worst air quality due to the Rockies. NOX is created by high temperature above 2500 degrees. When the fuel ignites it creates high pressure, and temps. To control the amout of NOX the EGR was designed.
What the Exhaust Gas Recirculation valve does is put exhaust gases back into the intake, which re-enters the cylinders. Some people believe it helps to reburn what wasn't the first time. What it acutually does, is takes inert exhaust gases back to the cylinder and takes up space. Less air/fuel mixture can get into cylinder, in turn, less pressure created and lower cylinder temps. The easiest way to explain it I've found when telling customers about it is:
It's like putting a brick in your toilet bowl. The brick takes up space so when the water is refilling, less water is needed to raise the float, in essence using less water.
Now if the valve is sticking open there could be problems, but that would also cause idle problems. The valve is not designed to be open at idle. The engine stumbles or dies. The valves are designed to open and close due to back pressure of the exhaust. Digital ones the computer controls depending on inputs.
I hope this helps
What the Exhaust Gas Recirculation valve does is put exhaust gases back into the intake, which re-enters the cylinders. Some people believe it helps to reburn what wasn't the first time. What it acutually does, is takes inert exhaust gases back to the cylinder and takes up space. Less air/fuel mixture can get into cylinder, in turn, less pressure created and lower cylinder temps. The easiest way to explain it I've found when telling customers about it is:
It's like putting a brick in your toilet bowl. The brick takes up space so when the water is refilling, less water is needed to raise the float, in essence using less water.
Now if the valve is sticking open there could be problems, but that would also cause idle problems. The valve is not designed to be open at idle. The engine stumbles or dies. The valves are designed to open and close due to back pressure of the exhaust. Digital ones the computer controls depending on inputs.
I hope this helps
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