EGR Block-off Plates

With a coolant reroute, a standalone ECU, and makeshift EGR tube made from plumbing parts, it was time to throw in the towel and block off the Miata’s EGR system. ’94 was the first year of Exhaust Gas Recirculation (EGR) in Miatas as emissions equipment. It activates under low-load cruise conditions and cycles some exhaust gas back through the intake to reduce combustion temperatures and NOx emissions. Read more about emissions testing here.

This block-off kit from MiataRoadster enables removal of the EGR system including blocking off the holes where the EGR valve attaches to the intake, and both ends of the EGR tube (on the intake and on the exhaust header). They also have different versions with plugs/caps for different years of exhaust header.

Technically, I think the smaller block-off plate is only decorative – because the passage where the EGR tube connects only leads directly to the EGR valve where the bigger block-off plate will be. The minimum install would be to remove the EGR tube, cap the exhuast header port, and leave the EGR valve installed to block the intake side.

MiataRoadster EGR Block-Off Kit
EGR connections on intake
Removed EGR valve and gasket
EGR valve port

One of the benefits of EGR system removal is now hot, sooty exhaust gas will not leave deposits in the air intake.

Block-off plates with RTV sealant
Installed block-off plates
EGR exhaust header cap
EGR header cap install
MiataRoadster EGR block-off plates$45
RTV Black Silicone Sealant$5

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