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Old 02-22-2003, 10:10 AM
pmckechnie pmckechnie is offline
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Join Date: Jan 2003
Location: Matthews, NC
Posts: 1,356
If the EGR valve has a small piece of carbon in the valve seat, it can cause
Poor idle
Unburned fuel from misfire
Rich mixture (the exhause diluts intake air, so less oxygen + same fuel = rich mixture)
Also it will cause a failure of the EGR valve. It is tested by closing the valve and checking the vacuum and mixture, then it open the valve and checks again. It should see a change. It won't if the valve is already open and stays that way.
SO replace the valve, clean out the EGR passages, and retest.

84 500 SEL (307,xxx miles)
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