1sttruck is right on with the mention of high combustion temperature... look into perhaps changing your plug to the next within range.
Last I fought high NOX on a 90 Accord, I replaced EGR after cleaning out the EGR port by hand. I changed plug range AND replaced the cat. After doing these three things my NOX had a value like that of your truck.. LOW.
Last I fought high NOX on a 90 Accord, I replaced EGR after cleaning out the EGR port by hand. I changed plug range AND replaced the cat. After doing these three things my NOX had a value like that of your truck.. LOW.
