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Exhaust Gas Recirculation (EGR) Valve

The EGR Valve is just above the exhaust pipe in the middle of the engine. It's purpose is to recirculate a portion of the exhaust gas back into the intake manifold, reburning it and keeping combustion chamber temperatures down, which aids in reducing emissions.
EGR Valve

- Details -

This is an original EGR valve, viewed from above and in front. The pintle is visible where it enters the exhaust manifold.

You can easily check for proper EGR operation by briefly cracking the throttle open so the engine reaches 2,500 rpm or so. You should see the pintle move slightly.

If it doesn't, check for ported vacuum at the EGR. The engine must be warmed up for this test. The EGR should NOT move if the engine is cold. If it does, this could indicate a bad CTO valve.
EGR Valve

If there is ported vacuum at the EGR valve but the pintle doesn't move, it is either stuck or the vacuum diaphragm is leaking. If you have the OEM type EGR valve where you can reach in with your fingers and touch the diaphragm, you can do a further test.

With the engine idling, reach in with your fingers and compress the diaphragm slightly, pulling the pintle out just a little. Be quick about it, as it gets quite warm. If your EGR valve is made in such a way that you can't reach the diaphragm, manually apply vacuum to it to run this test. The engine should choke and gag. Release the diaphragm (the pintle should go back in) and the idle should smooth out. If doing this changes the idle little or none, then something is clogged, either the EGR port or the exhaust feedback tube.

The EGR is easy to remove. Check it and the manifold for a buildup of carbon deposits, which you may be able to clean. A new EGR valve costs about $70. Be advised that even a new EGR valve will not hold vacuum, so don't make the mistake of assuming this means that it's defective.

Details about EGR Vacuum

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