My neighbor is looking at possibly buying a YJ for a project but it seems like all of the ones he has looked at will not pass smog. Is there any one particular thing he should look for? He is pretty knowledgeable about cars but he wanted me to ask the professionals about a JEEP.

 

I had two YJ's (91' and a 95') and they can be kind of tricky with emissions testing because the earlier ones used an emissions pump that was too small for the carbureted 4.0L engine. I'd do the basics first (going in order of expense):

- New air filter
- New PCV valve
- Check O2 sensor on exhaust manifold (replace if questionable)
- Check float valves on carb, these can wear their seats and cause the motor to run rich
- Replace emissions pump, replace it with one from a 93' or newer YJ (I think that was the year they improved them)
- Check Cats (they wear out)

It's been 15 years since I touched a YJ but these are the things I can remember that I did to pass CA emissions.

 

Thanks!! I'll give him the info.

 

sdr0303 is dead on. When I had issues with my 88YJ passing CA's smog I ended up replacing most of the parts listed with the O2 sensor being the final item to allow me to pass at a "Smog Only" shop.

 

that stinks. i just retired my 95 yj and there is no emission tests for pre 96s in mass. good luck. the 95 was my second favorite vehicle i've owned, only to my '90