Houbill

My 1993 5.0 LX just failed the Nox test for my State Inspection renewal. The reading was 1122, allowable 796. The Nox on the two years prior inspections was 396. The car was driven less than 800 miles since the inspection last year. The mileage is only some 60000 miles. Suggestions?

mjr46

run a koer test and look for any egr codes, nox is produced as a result of high combustion temp often due to inoperative egr system or excessive carbon build up in the cumbustion chamber/on tops of pistons

88LXdad

sea foam the motor and tune it up and get it good and hot before taking it to testing.

mjr46

^^^I doubt in 800 miles it went from a low nox output to excessive from carbon build up....as I stated run a koer test and look for egr codes, I bet something on the egr isn't working