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Franke · 05-10-2013

Can anyone tell me why a 1990 LT5 would fail emissions with 3.9ppm Nox? The car has 55,000 miles on it and runs great. The max Nox limit in this state is 3.5 ppm. The HC and CO are well within limits. Some emissions people tell me to check the EGR but I don't think the LT5 has a EGR. The local Chevy dealer thinks the cats are failing but can't go any farther. Any help would be appreciated.

05-10-2013	#1
Franke Join Date: May 2013 Location: Beaver, PA Posts: 515	1990 LT5 emissions fail Can anyone tell me why a 1990 LT5 would fail emissions with 3.9ppm Nox? The car has 55,000 miles on it and runs great. The max Nox limit in this state is 3.5 ppm. The HC and CO are well within limits. Some emissions people tell me to check the EGR but I don't think the LT5 has a EGR. The local Chevy dealer thinks the cats are failing but can't go any farther. Any help would be appreciated.