Aircare (smog) issue.

[jgranthevagrant]

Truck is a 1990 22re. Just passed aircare today, but with very high NOx readings. Passed with 1152 parts per million. Maximum allowable is 1155 parts per million. Question would be what part of the emissions system would be defective to have the oxides of Nitrogen this high?

 

[pappy]

Truck is a 1990 22re. Just passed aircare today, but with very high NOx readings. Passed with 1152 parts per million. Maximum allowable is 1155 parts per million. Question would be what part of the emissions system would be defective to have the oxides of Nitrogen this high?

NOx is reduced by the EGR valve. Check the valve and modulator. Also make sure the vacuum hoses are hooked up correctly.

 

[jgranthevagrant]

Thanks. I will look at the hoses etc before tearing the old one off.