I just purchased an 85 cherokee with the 2.8L V6. Had I known what an idiot the last guy to work on this was, I would have refrained, but the price was right (next to nothing).

I found that the emission control components have been removed, and many vacuum lines were leaking. I finally got it running pretty good, but I do have a couple of minor issues to deal with next.

First, the catalytic converter has been removed. Why? Anybody's guess.
Will the 02 sensor send bogus info now? Or does it matter where there is only one sensor ahead of the cat?

Second, the fuel mixture screw has been tampered with. Does anybody know where this screw should be set?

Third, I have a hard time getting it to run smooth until it is warmed up. I did repair the choke as the electrical connection had been broken off. Starts just fine, but takes a little time before it gets warmed up and able to drive without nursing it along. Perhaps the mixture screw has something to do with this?

Before I start getting flamed for not having a cat, let me state that the vehicle came this way, although I realize that it is a federal law to have one, Idaho does not have inspections and frankly I don't give a damn if it has one or not as long as it runs like it should. My big concern about the cat is the 02 sensor.

Thanks in advance for any info on this, I am the first to admit that I am not much of a mechanic with these newer motors. Just gave away my age, didn't I?

 

I don't have any experience with this engine, so i can't answer the specifics, but..

The o2 sensor doesn't care whether there is a CAT after the sensor or not, it simply reads the burnt air/fuel mixture ratio and adjusts accordingly.

If it's running choppy until it's warmed up, i'm guessing that it is running too lean at startup, and the set screw should be adjusted to allow a richer a/f mixture.

 

A V6?

 

yea the V6 came on XJs 84-86 (alternative to 4cyl)

 

You stated that the choke wasn't working right. I'm not familiar with the 84-85s but does it have a carb? If it does, they just run crappy until they are warmed up.

 

I also have the same year/engine setup and know that it does have a carb and does run a little ruff untill warm. But i am also interested in this as mine seems to be running to rich.