Automotive Forums

I have a 1994 Jeep wrangler with a 2.5l motor. The smog laws in California require I smog it every other year. Once again it fails the smog check. I changed the oil, plug, cap, rotor and Cat. It still fails with high NOX there is not a EGR valve and the cat is new. Does anyone have any idea if this is common on this year model or motor type? The jeep has alow geared rear end and larger tires(33"). Because the smog is done on the dyno is it possible the drive train is effecting the load range,spark curves or the computer. Any help would be appreciated.

Jim