cannot pass emissions any suggestions?

[mayonaise]

i have an 88 jeep cherokee that won't pass emissions the main problem is that my carbon monoxide is too high, hydro carbons are not the problem, i was woundering if anyone could offer some help. it has new oil and new air filter, plugs are good. any help would be greatly appreciated. also it is the 4.0L 6cyl engine.

matt

[89ltd]

it could be the o2 sensor, it is directly related to the fuel/ air mixture. I have an 89 cherokee and it failed the emissions as well. My hydro carbons are to high, the n0's just made it, but I replace the o2 sensor before going in and cO is only 11-(48 limit) while driving and at idle it is .01 (1 limit). The o2 sensor is located in the exhaust manifold , it screws in like a spark plug with wire connector on it. The o2 sensor sends an electrical signal to the computer , then the compter will adjust the fuel injection. I have back probed the signal wire before and it should vary with engine load ect. The signal is .1 volts dc to .9 volts dc , .1 volts being lean and .9 , rich. The engine will run with a faulty o2 sensor but will suffer fuel economy, power. When the sensor if faulty, the computer will lock in a loop mode and set the voltage at around .5 volts all the time. In other words, maybe change the o2 sensor, I think this is your problem. Now what about mine guys, high hc's, I'm waiting for a pickup coil for the distributor, have done the plugs , egr valve, wires, cap and rotor, o2 sensor, crank sensor, air filter, etc....