failed NOx emission

[fletchcountry]

My 94 xj just failed an emission test in Utah. The tech said my NOx was too high and the problem was timing, cat converter or EGR valve. I put a new cat on two years ago with a stage 2 chip and the timing is computer controlled. Would the egr valve cause high Nox readings and is it possible to change the computer settings for the timing? What are my optoions?

 

[ehall]

The HO engines (91 up) don't have EGR.

The stage 2 chip probably has the timing advanced. Pull it off and test again.

High NOX is usually indicates high levels of heat. You're probably running lean.