1998 yj failed emissions

[bboyroxas]

I just got this jeep it failed emissions and my results are as listed
HC: 592 fail limit is 220
CO: 3.92 fail limit is 1.20
Any suggestions to what it might be it runs fine

 

[8177]

Just going through that myself. Some my be able to tell by the numbers but I can't. I'll give you a place to start though. If you happen to have one of those thermometers that you point a laser at what you are measuring go dig it out. If you don't have one they are not that bad in cost. They are certainly cheaper than what a shop will charge to tell you your Catalytic converter is going bad. Start the YJ up and let it run for 5 minutes or so or drive it around for a while. With it running point the laser at the inlet tube as close to the cat as you can. Don't point at the heat shield, make sure you are measuring the metal of the cat. Write this down or remember it. Then to the outlet once again measuring the metal of the cat. not the pipe or shield. The temp should be significantly higher on the output than the input. If not then the cat is failing. Or if you have the ability to scan for codes look on you tube, The voltages on the two O2 sensors should tell you. One sensor should stay fairly steady and the other one should vary a lot. I don't remember the voltages. I had one of the thermometers and went with that. Mine was 150 degrees less at the out than the in. Bad Cat!!!

I feel for you brother. I am going through that on my 81 also

 

[Catoctin Jeep]

8177 has some good points on checking the cat. Also, when was the last tune-up and oil change. The timing can be off as well and still run good. Just go over everything and decarb the throttle body.

 

[bboyroxas]

I realized my idl was at 900 and I am playing with the timing and carb got it at 600 now

 

[8177]

What do you have the timing set to?

 

[69jeepcj]

When you increase the timing, your idle will go up. You have to turn the idle back down with the idle screw on the carb. Oh, and a 98 would be a TJ so im not sure you have a carb, but should be a idle screw somewhere.

 

[8177]

What I read, but not sure if you meant to say it that way so forgive me if I suggest somthing you are well aware of. Set you timing to 6 to 8 BTDC unless you know it is supposed to be different because I don't have your specs in front of me. Then adjust your Idle speed and re-check your timing. If you Have Vacuum advance on your distributer unhook it and plug the hose so it wont act like it had a leak.

 

[bboyroxas]

I'm sorry it's an 1988

 

[jkruegel]

My 92 yj has a problem with smog as well, I replaced just about every thing under the hood. I live in So. Ca and they are really bad/tight with their specs. I ended up transferring my jeep to Imperial County where they only do a rev test instead of putting it on the dyno. Good luck

 

[bboyroxas]

I used a timing light to get the timing down and them I adjusted the carb I took it to get tested again and the thing failed it was missing at about 2500 rpm that's what they make u hold the throttle at and yet I have a good idle at 600 rpm