1992 Jeep Cherokee Laredo 6 Cyl 4.0L
Failed smog, replaced oxygen sensor and cat. Readings were good but NOX to high. Replaced cap, plugs and wires stil high
Running too rich
NOx (oxides of nitrogen) is a tailpipe emission caused by the oxidation of nitrogen in the combustion chamber. When the peak combustion temperatures go over 2500°F (1371°C) NOx is formed in excessive amounts. To keep the combustion temperatures down, exhaust gas is recirculated.