my friend was worried his 83 2.8 wouldnt pass, so i told him to put like 3 bottles in while he had low gas and take it in. his HC's were extrememly low, as well as the CO....but the NOX was wayyy up. later that night he said he talked to his brother, and according to him too much drygas will make the combustion cooler, raising NOX while the HC and CO drops (this might not be exactly what he said, this is translated through a person who doesnt know cars well) anyway, he basically said the NOX was up high cause of too much drygas...sould this be the case??? also, what are some other reasons for the NOX to be high???? thanks!!!! ------------------ 85 Z28- 350, Comp 262, Edelbrock Performer intake, Edelbrock 600 cfm carb and Edelbrock cat back, Summit headers and vette servo -JVC, Eclipse, Pioneer, MTX, Phoenix Gold, Planet Audio

Actually, high NOx levels are caused by high temperature and high pressure... the EGR lowers NOx readings; when it lets exhaust gas in, the exhaust gas actually cools down the explosion. I'd say to check out the EGR, and maybe the cat convertor. Did they have the 3-way cat's in '83?



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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
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Tom is right about the high temps causing NOx emmisions, and your friend's bro was right about the drygass possibly causing the NOx. Drygas is alcohol, which carries oxygen with it, effectively leaning the mixture out. Lean mixtures burn hotter and thus tend to produce more NOx.
It can't hurt to check the functionality of the EGR as well.
...ed