The EGR valve on your 1997 Nissan Maxima uses a transducer-type ERG system. The valve opens when the Maxima is running to allow air back into the air intake to be burned again to reduce NOX emissions. A side benefit is that the engine's operating temperature drops so the engine runs somewhat cooler than without the EGR system. However, significant carbon build up is an inherent problem with an EGR valve and this is no exception on the Maxima. When your EGR valve fails, you'll need to replace it.
Mark the location of the vacuum lines running to the transducer and EGR valve using masking tape and permanent marker so that, when you reconnect the valve, you can be sure how the vacuum lines were originally routed. Then disconnect all of the lines from the transducer and the EGR.
Unbolt the tube nut fitting on the side of the EGR valve using a tube nut wrench and gently move the tube out of the way.
Unbolt the EGR mounting nuts and pull the EGR valve away from the intake manifold.
Remove the old EGR valve gasket.
Spray the mating surface on the intake manifold with carburetor cleaner. Then wiper the area clean and make sure it is free of debris.
Loosen the nut that secures the transducer solenoid and remove the transducer.
Secure the new EGR valve, gasket and transducer to the intake manifold with their respective mounting nuts. Tighten the EGR valve and transducer solenoid nuts to 12-14 ft.-lbs. using a torque wrench.
Reconnect vacuum lines that you removed in step 1. Then, reconnect the tube and tube nut to the fitting on the EGR valve using a tube nut wrench.
