EGR Failure Symptoms..?
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Postmaster
Joined: Jun 2004
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From: B/CS, Texas!!
EGR Failure Symptoms..?
What are a few? I think my EGR valve is malfunctioning. Rough idle, some hesitation, bad mpg. It also stalls at idle or at very low speeds(0-10mph). The stalling happens only after engine is warmed up.
Any suggestions? Thanks
Any suggestions? Thanks
Senior User
Joined: Jun 2003
Posts: 352
Likes: 1
From: Tillamook, Ore
Pull your computer codes to see if somethings wrong. If you're convinced it's the EGR valve, pull some vacuum on the valve and see if it holds. If it does it could be any number of sensors or vacuum lines.
Elder User
Joined: Sep 2004
Posts: 941
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If the EGR is involved in the symptoms you describe, about the only way it could have failed is for the pintle to be carboned up and the valve is failing to close when it should. This would allow exhaust gas recirculation at idle, which makes for rough running and stalling.
The diaphragm, EVP, hoses, etc are all involved in opening the valve to cause EGR when the PCM wants it. If these components fail, the typical symptoms are part throttle knocking and detonation -- since the computer counts on the exhaust gas flow to reduce peak cylinder temperature in these circumstances and sets the spark advance and mixture ratio with that in mind. If the diaphragm leaks badly, the valve cannot open. But in this case the EGR would not impact idle quality because the valve is held closed by a spring.
If the pintle is stuck, that should be reflected by the EVP, and the computer should complain about EVP during a KOEO test.
Or you could do it the old fashioned way -- pull the valve off and visually inspect for free movement and seating -- apply a vaccuum and watch the pintle move, etc.
The diaphragm, EVP, hoses, etc are all involved in opening the valve to cause EGR when the PCM wants it. If these components fail, the typical symptoms are part throttle knocking and detonation -- since the computer counts on the exhaust gas flow to reduce peak cylinder temperature in these circumstances and sets the spark advance and mixture ratio with that in mind. If the diaphragm leaks badly, the valve cannot open. But in this case the EGR would not impact idle quality because the valve is held closed by a spring.
If the pintle is stuck, that should be reflected by the EVP, and the computer should complain about EVP during a KOEO test.
Or you could do it the old fashioned way -- pull the valve off and visually inspect for free movement and seating -- apply a vaccuum and watch the pintle move, etc.
Elder User
Joined: Feb 2004
Posts: 553
Likes: 0
From: North Bend Washington
also check the little filter under the cap on the EGR control solinoid. if that filter is plug it will cuase the EGR to open slightly at idle and just off idle. the solinoid will vent a very small amount of vacuum to keep the EGR closed at idle/off idle. mine was all nice and crudy, took off filter and sure enough EGR went closed. all it is is a tiny little sponge filter that sits on top of the solinoid vent.
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