High NOx, CA Smog
Thread Starter
Member
Joined: Dec 2011
Posts: 149
Likes: 1
From: Menifee, CA
Year: 1989
Model: Cherokee
Engine: 4.0
High NOx, CA Smog
I'm having trouble passing smog. The specs on the jeep are as follows.
1994 Cherokee, stock 4.0 with about 260,500 miles. Motor has not been rebuilt as far as I know.
I replaced the catalytic converter, spark plugs and wires 2 years ago. I have put maybe 1,000-1,500 miles on the jeep in the last 2 years.
The first test I didn't do anything to the jeep other than put some fresh gas in it. I failed due to high NOx on the 15mph and 25mph test.
For the second test I replaced the 02 sensor, put a new muffler on, fixed a couple vacuum leaks and aired up the tires.
The second test I passed the 15mph test but on the 25mph test my NOx went up.
I'm not sure what to replace next, any suggestions?
1994 Cherokee, stock 4.0 with about 260,500 miles. Motor has not been rebuilt as far as I know.
I replaced the catalytic converter, spark plugs and wires 2 years ago. I have put maybe 1,000-1,500 miles on the jeep in the last 2 years.
The first test I didn't do anything to the jeep other than put some fresh gas in it. I failed due to high NOx on the 15mph and 25mph test.
For the second test I replaced the 02 sensor, put a new muffler on, fixed a couple vacuum leaks and aired up the tires.
The second test I passed the 15mph test but on the 25mph test my NOx went up.
I'm not sure what to replace next, any suggestions?
CF Veteran
Joined: Mar 2010
Posts: 1,441
Likes: 9
From: Georgia
Year: 99 94
Model: Cherokee (XJ)
Engine: I6
I'm having trouble passing smog. The specs on the jeep are as follows.
1994 Cherokee, stock 4.0 with about 260,500 miles. Motor has not been rebuilt as far as I know.
I replaced the catalytic converter, spark plugs and wires 2 years ago. I have put maybe 1,000-1,500 miles on the jeep in the last 2 years.
The first test I didn't do anything to the jeep other than put some fresh gas in it. I failed due to high NOx on the 15mph and 25mph test.
For the second test I replaced the 02 sensor, put a new muffler on, fixed a couple vacuum leaks and aired up the tires.
The second test I passed the 15mph test but on the 25mph test my NOx went up.
I'm not sure what to replace next, any suggestions?
1994 Cherokee, stock 4.0 with about 260,500 miles. Motor has not been rebuilt as far as I know.
I replaced the catalytic converter, spark plugs and wires 2 years ago. I have put maybe 1,000-1,500 miles on the jeep in the last 2 years.
The first test I didn't do anything to the jeep other than put some fresh gas in it. I failed due to high NOx on the 15mph and 25mph test.
For the second test I replaced the 02 sensor, put a new muffler on, fixed a couple vacuum leaks and aired up the tires.
The second test I passed the 15mph test but on the 25mph test my NOx went up.
I'm not sure what to replace next, any suggestions?
I burned half the sea foam can then let it sit for a few minutes and burned the rest. Doing this dropped my box a couple hundred ppm on both tests.
Last edited by MonacaYankee; Nov 21, 2017 at 12:04 AM.
