So i'm fighting SMOG testing. The bonehead that owned my 98' XJ before me had a brand new Magnaflow cat welded on. It is just upside down and for the wrong vehicle application - EO number is for a GC.
So, here i am trying to pass smog inspection. My emissions are frickin great though.

My Cherokee came from out of state - i think Oregon or Washington. How many cat converters am i supposed to have? The one that i've been referring to is the one a few inches rear of the transfercase. Is that the "rear" cat??? Or, is there a front cat somewhere???
When cat shopping, i'm finding that there are supposedly 2 cats on this car. I didn't see any on the downpipe, but maybe i missed a super tiny one? I know factory exhaust systems can vary, especially out here in CA. This car is federal, so... ????

Also, what is the inlet and outlet diameter of the cat rear of the transfer case???


Thanks!!

 

Im pretty sure yours only has the one, I know the 2000 and 01 models had pre-cats in em though. They're inspecting your jeep in Ca? I've never been that thoroughly inspected to notice which direction my cat is pointing. If yours is passing why are you worried? Stock exhaust is 2.25 throughout iirc

 

^^ What he said.

2000 model years came with Federal Emissions (main cat near transfer case), which was standard on all previous model years, or California Emissions, which has two small converters in the exhaust manifold as well as the big one. 2001 and later 4.0s seem to be exclusively the California version.

 

Magnaflow actually lists two cats for your XJ.

 

Because you can pass on the sniffer, and still get downchecked from a visual (don't ask - I don't like it, I think it's stupid, and I wish they'd stop. I got downchecked once for a failed EGR on my 87 - despite the fact that my sniffer numbers were excellent! I put on a new EGR, and everything jumped to "just passing" - but at least I passed visual...)

So, this doesn't really surprise me.

OP - Stock exhaust size for the 6-242, all years, was 2.25" ID (as I recall.) Being OBD-II, you may have two cats in line, check. However, you should not have that wretched split exhaust header with the two pre-cats, that was 2000-2001 only for the XJ.

Check the VECI label underhood - at the bottom of the label, it will tell you if it's "49-state Spec" or "CA Spec" - this can make a difference getting smogged. If you're 49-states, then the E.O. # should not apply, since that's strictly a California thing.

 

Ours measures 2.5" at the cat inlet and 2.25" at the cat outlet/muff inlet.

 

This is an undeniably fascinating thread.
Soo many stupid hurdles in CA. My emissions are clean as can be, but i still can't pass smog.

 

Do not get me started! I had the dubious privilege of embarrassing the Acting Regional Director & Acting State Director of CARB when I got invited to a workshop before SCII was rolled out statewide.

Mainly, by asking questions they couldn't answer - and when they tried to fall back to a "pat answer" (usually, blaming Federal regs,) I could prove them wrong there - since I had copies of the Federal regs with me.

The answer for why things are done the stupid way 'round seems to be "That's the way we've always done it."

Just because that's the way you've always done it doesn't mean it's the right way 'round, or the best way 'round...

I got all my vehicles sent to "Test Only" stations for the next six or seven years. Pain in the ****...

 

Just one single cat????
You have the setup i have. My piping has the same dimensions

 

Yep, one cat.

 

Is anyone really seriously trying to make sense out of the baboons who run Ca smog emissions boards? Commit yourself now because there is no answer. Just try swapping motors for one more efficient and better mpg. What happens is the one donating the most money or 'other services' gets appointed to positions of large salaries. And if you embarrass them, you get a lifetime supply of hassle.
Did your Jeep smog pass?

 

Oh you can make sense of it, but you have to be a part of the system(or worked within it) in order for it to really blow your mind.