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trop-a-cal's avatar
trop-a-cal
Explorer
Oct 20, 2013

1997 454 GM vortec motor problem with EGR Valve

I noticed the idle down lower than normal and a weak start. Then a pinging, and loss of power after a full up when tank was almost empty. I was told the exhaust system has a valve, that recycles exhaust fumes from gasoline, that can stick causing these problems, which are then worse and shut the engine down completely due to the valve sticking open. And so it happened and in to the shop it went and is. The engine started knocking after the pinging, but full power was there when it ran at interstate speeds. It did dog and have low idle when at low speeds and at stops. EGR Valve- Exhaust Gas Return Valve, is its name. Tell me if your 1996-1999 Chevy vortec did that and was cured with new valve and at what cost. Thanks

4 Replies

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  • bucky's avatar
    bucky
    Explorer II
    Oct 21, 2013
    That year truck will have OBD2 emissions and will set a code for any emissions fault. Including EGR. Do you have a CEL on and if so what is the code?
  • doxiemom11's avatar
    doxiemom11
    Explorer II
    Oct 20, 2013
    We had one that did this - rough slow idle, had to keep foot on brake and a little gas next to keep running, Once going, went okay. Service Engine light came on and idle would be worse. EGR valve was plugged up with carbon deposits. DH would remove valve, blow the carbon out with the compressor and it would be good for about 6 mo, then do again. He would clean again. Never did replace the valve - got rid of vehicle a couple years later and it was still running great with a cleaned out EGR valve. Ours must have been working properly when not carboned up.
  • ScottG's avatar
    ScottG
    Nomad
    Oct 20, 2013
    Those are classic EGR failure symptoms.
    Sometime when it's acting up, unplug the vacuum line to the EGR valve and cap it off - you might have to tap on it a few times to make it seat properly. If it runs fine after that then you've found your culprit. Don't leave it that way too long though as it will cause detonation you may not hear esp on hills.
  • ktmrfs's avatar
    ktmrfs
    Explorer II
    Oct 20, 2013
    an EGR valve that is open at idle (which it should not be) or with no throttle often cause very poor idle or stalling. had that problem with a 95S10 4.3 litre and new egr valve fixed the problem. sounds like yours is not closing all the way. If it sticks full open usually you can't even get it to idle, will stall.

    don't know cost, mine was a warranty repair.

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