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We dismantled an EGR system for show and tell. The cylinder head is on top of all the fun. Fuel and air is drawn into the combustion chamber when this valve opens on a piston down stroke.
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The piston compresses the fuel and air up into the cylinder head. The spark plug ignites it. Boom. Piston goes down on power stroke. The piston pushes exhaust out of this valve on its way back up.
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A light shining from the intake side reveals the EGR exhaust passage from the exhaust port.
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Here is the same exhaust passage on the intake side. The purpose is to channel exhaust back into the intake.
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The exhaust travels through the passage and through a port in the intake manifold to the EGR valve itself.
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Commands sent to the EGR valve by way of vacuum lines or computers tell the valve when and how much exhaust to port back through the engine.
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The exhaust passage was clogged with carbon at the EGR valve. Cleaning the passages will help restore EGR system performance.
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The EGR valve itself was also full of carbon. The small plunger is what meters exhaust back into the engine.
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When the EGR valve opens exhaust enters the intake manifold here and travels back into the combustion chamber to reduce NOx emissions.
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The EGR valve is usually located on the intake manifold. Note vacuum hoses and control solenoids for EGR valve.
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