1988, 4.0L, Auto, 2wd, 175K.
1st Test:
15MPH: HC:18ppm, CO: 0.10% NO: 1218ppm (fail)
25MPH: HC:15ppm, CO: 0.07% NO: 1030ppm (fail)
Replaced Exh manifold gasket and resealed TB, and EGR gaskets
Tested EGR solenoid and valve (OK), cleaned
Replaced TPS (it was shifting a bit funny)
Replaced CAT (got direct fit) and muffler (Cherry Bomb Turbo). Muffler had a bunch of holes and cat rattled a little.
Added some octane booster to tank
2nd Test:
15MPH: HC:34ppm, CO: 0.05% NO: 68ppm
25MPH: HC:18ppm, CO: 0.01% NO: 53ppm
The NOx improvement was pretty dramatic. The items above needed to be done anyways. I decide to try the first smog test to see if it could pass so I'd be able to wait a bit on the cat and muffler. Since I failed, I figured I might as well get 'er done.
Now I'm good for 2 more years.
1st Test:
15MPH: HC:18ppm, CO: 0.10% NO: 1218ppm (fail)
25MPH: HC:15ppm, CO: 0.07% NO: 1030ppm (fail)
Replaced Exh manifold gasket and resealed TB, and EGR gaskets
Tested EGR solenoid and valve (OK), cleaned
Replaced TPS (it was shifting a bit funny)
Replaced CAT (got direct fit) and muffler (Cherry Bomb Turbo). Muffler had a bunch of holes and cat rattled a little.
Added some octane booster to tank
2nd Test:
15MPH: HC:34ppm, CO: 0.05% NO: 68ppm
25MPH: HC:18ppm, CO: 0.01% NO: 53ppm
The NOx improvement was pretty dramatic. The items above needed to be done anyways. I decide to try the first smog test to see if it could pass so I'd be able to wait a bit on the cat and muffler. Since I failed, I figured I might as well get 'er done.
Now I'm good for 2 more years.