EGR Valve--Whats-Up!!!!
Thread Starter
Instructor
Joined: Jul 2004
Posts: 106
Likes: 0
From: Brandon Mississippi
EGR Valve--Whats-Up!!!!
1980---Got all the vaccum lines run CORRECTLY (finally) on the Smog System. BUT!! the Egr valve is cycling (opening & closeing) at idle (about 750 rpm). Temp. is 180-190-- motor is running ROUGH!!!! I thought(for what it is worth) the EGR valve would open above a idle---like-- at "cruise speed". Does this mean that I have a bad EGR valve-- OR--is there something else that would make the EGR Valve cycle at idle..
JUST a thought????? what if I disconnected the EGR Valve.... Thanks for any HELP on this problem.
JUST a thought????? what if I disconnected the EGR Valve.... Thanks for any HELP on this problem.
Racer
Joined: Aug 2001
Posts: 388
Likes: 1
From: Bridgeport CT
Sir:
Make sure everything is hooked together properly before you start to replace any components. When they are boogered up, strange things happen.
Geoffrey Coenen
Wanted: 69 L89 convertible. No project.
Make sure everything is hooked together properly before you start to replace any components. When they are boogered up, strange things happen.
Geoffrey Coenen
Wanted: 69 L89 convertible. No project.
Tech Contributor
Joined: Aug 1999
Posts: 14,382
Likes: 6,401
From: At my Bar drinking and wrenching in Lafayette Colorado
Make sure the EGR is hooked up to ported vacuum - not manifold vacuum. Ported vacuum does not provide any vacuum signal at idle, so the EGR cannot open. The ported vacuum source on a post-'75 Q-Jet is the nipple located in the baseplate of the carb on the forward passenger side - it sticks out at about a 45-degree angle. There should be no vacuum on this port at idle. If you're getting vacuum at this port at idle, you have other engine issues that are causing you to have the throttle blades opened at an excessive angle, allowing manifold vacuum to reach the ported source.
