Emissions Test Results: Problems

Plugged up air filter or bad O2 sensor?

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

"d.g.f." wrote:

Oxygen sensor would be the first suspect, assuming no trouble codes are stored for anything else (you should be able to retrieve them if there are any with a jumper wire on this vehicle, my site below has instructions). It's clearly running way too rich, 8% carbon monoxide is exceedingly high. Quite likely you will notice the gas mileage improve as well..

Could be a bad CAT or O2,could be quite a few things for that matter. But hey,how about checking the basics first?When was the last time you had it tuned up?Does the car run ok?Give a little history of the vehicle.Sometimes that will make a world of difference in finding out whats wrong with your vehicle.

Don't worry about the NOX. Oxides of Nitrogen only form when the combustion temp is too high, say over 2500 degrees.

Your HC (hydrocarbons) is unburned fuel, and your CO (Carbon Monoxide) is partially burned fuel. Also notice the O2 is minimal, which suggests it does not have a misfire. It's running too rich for some reason. You can start back at the basics: Plugs, contaminated oil, dirty air filter, bad O2 sensor (or just a slow one), incorrect coolent temp sensor, incorrect IAT sensor, bad/plugged PCV system.... The list goes on.