EGR causing miss?
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Cross-Country
Joined: Feb 2003
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From: Poughkeepsie,NY
EGR causing miss?
After I replaced my exhaust gaskets I have developed a bad miss. (I have replaced the wires, cap, rotor, plugs, coil, pcv, injectors) Could a bad EGR valve cause this? I only have 48k on this motor.
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Joined: Oct 2002
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From: Seattle/Tacoma Washington U.S.A.
EGR causing miss?
what motor and what year? I have had a similar problem... I bought a new intake (without EGR) and it did not solve anything.... But part of what I thought was a missfire, was an exhaust leak, I fixed it and it was a little better, but I still have the same problem as you....
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Joined: Aug 2002
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From: Minneapolis, MN
EGR causing miss?
Is the miss steady, specific to one (or two) cylinder(s) or is it a random, generally rough running, poor idle quality type of miss?
Usually an EGR valve will act up in one of two ways.
1) Leaky diaphragm; won't apply, engine pings. (Not your symptoms)
2) Carbon buildup; can partially hold valve open at idle, causes rough idle, possibly won't idle, but will still run OK under load and at higher RPM's. (Hmmm?) Carbon can build up to the point where it completely blocks off the passage and acts like the valve isn't working at all.
If the miss is a steady dead cylinder, it probably isn't the EGR.
What happens if you apply vacuum to the EGR valve with the engine at idle? It should stumble and die.
Have you double checked the firing order?
Have you checked compression?
Just my 2¢
Greg
Usually an EGR valve will act up in one of two ways.
1) Leaky diaphragm; won't apply, engine pings. (Not your symptoms)
2) Carbon buildup; can partially hold valve open at idle, causes rough idle, possibly won't idle, but will still run OK under load and at higher RPM's. (Hmmm?) Carbon can build up to the point where it completely blocks off the passage and acts like the valve isn't working at all.
If the miss is a steady dead cylinder, it probably isn't the EGR.
What happens if you apply vacuum to the EGR valve with the engine at idle? It should stumble and die.
Have you double checked the firing order?
Have you checked compression?
Just my 2¢
Greg
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Cross-Country
Joined: Feb 2003
Posts: 71
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From: Poughkeepsie,NY
EGR causing miss?
It's a '92 351w non-roller. It is a steady miss. I've checked the firing order, checked for bad wires, etc. I"m going to do a compression test this weekend and see how that results. This miss didn't start until I replaced the exhaust gasket and pulled the EGR away from the manifold. Maybe it's just a coincidence.
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