egr valve explanation

Discussion in 'Performance & Fuel' started by newcheylover, Mar 24, 2013.

  1. newcheylover

    newcheylover Member 1 Year

    How does the egr valve work on a 1989 Chevy Silverado with a 350. Its mounted behind the tbi about 5 inches. I have an 01 with the 5.3 and a tube comes off the headers to the egr on the throttle body but does exhaust go up through the manifold? Please help im vary confused
  2. dobey

    dobey Epic Member 5+ Years 500 Posts

    Not sure what you're asking exactly. The 1989 EGR is probably vacuum actuated, and the 01 EGR is probably digital and controlled by the ECM.

    Does not explain enough about the process itself? Or what specifically are you trying to learn?

    99'HEARTBEAT MODERATOR Staff Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    I think the Tubes that your asking about, that are coming off the Exhaust Manifolds "Your Headers"??......are the Check Valves Number #4 is the Tube and Number is the Check Valve #5........for the SECD Air Injn "The Air Pump" which is Number #10

  4. newcheylover

    newcheylover Member 1 Year

    I know what it does but im asking about the 89 sorry about the confusing question. I'd like to know how it works. I dont see any tubes going to it just a wire.
  5. dobey

    dobey Epic Member 5+ Years 500 Posts

    OK. I can't find a parts diagram, and all the EGR Valve part results I've found look almost exactly like the EGR Valve that's on my Fiero, so I presume it operates the same way (vacuum actuated EGR valve). The way it works is it mounts on the exhaust somewhere. There's a cast iron portion, which contaings the valve itself, and a portion above that, which contains a rubber diaphram and a vacuum port. Vacuum pulls the rubber diaphram up, to open the valve, and exahust gas flows through that valve, and through a tube that attaches on the side of the EGR, and then to the intake somewhere. I'm not sure where it attaches on the TBI intake, but on my 2.8 Fiero, it mounts to the underside of the intake neck, just behind the throttle body. The EGR valve itself mounts on the Y-pipe which is near the throttle body (transverse layout with throttle body above the trans end of the engine).

    I guess it works similarly on your 89 CK truck. Is there a Y-pipe going across the top of the transmission with the EGR mounted up top near the firewall?
  6. newcheylover

    newcheylover Member 1 Year

    Ill have to take a closer look I didn't know what I was looking for at the time but now I have something to go on
  7. marksoldtowne

    marksoldtowne Member 1 Year

    hi everyone
    TheEGR valve controls a small passageway between the intake and exhaust manifolds.When the valve opens, intake vacuum draws exhaust through the valve
    ,it also reduces the engine's octane requirements which lessens the danger ofdetonation.The main responsibility of an EGR valve is to re-circulate the gasses from a vehicle's exhaust to the intake. EGR valves helps cut down on harmful and dangerous exhaust emissions.Carbon build- up in EGR valves can cause it to be blocked and stuck. Cleaning it can help solve the problem.

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