Just went and had my 91 XJ smogged, it failed in every category

Numbers at 25MPH are:

HC-
max:72
meas:105

CO-
max: .65
meas: .76

NO-
Max: 711
Meas: 1233

So I'm guessing that my catalytic converter is bad, maybe even my O2 sensor (I'll check that). I was just wondering if someone could recommend a good cheap catalytic converter that they've had success with. I'm inclined to go to autozone and buy a universal one and throw it under there but I've heard they're not that great. Any input?

As for NO, I'll check my timing, i'm suspect that might be the cause.

 

The timing should have been checked as part of the inspection. Have you done any type of maintainence or made any changes to the engine lately?

 

I just bought it, did a tuneup, changed oil, replaced the map and tps sensor. It runs great now.
I have seafoam in the gas tank right now, didn't think it would affect the test but could it?

 

Some simple tips that will get you past the test.
NOTE: I said "past" the test. There's another one in two years.......

A fresh cat. Gotta pass the visual too.
If possible back off the timing two degrees max.
With a light load of fuel, add a pint or two of denatured alcohol.

Burn off the seafoam before returning to the test center.
And bring the car in HOT and a few minutes late for the test.
That way there's less time to cool off the cat.

 

^ the trick is to be HOT...hop on the freeway for 20 miles and or a large long hill and make it work ...that cat has to be HOT....also,,,if you have an oil burner may want to switch to synthetic prior to a smog...your hydocarbons will be in check if you do
cameron

 

I recently checked pricing on California-compliant catalytics… twice the price of 49-state catalytics! Magnaflow gets $100 for the 49-state version and $209 for the California version. (Thank you California politicians!)

Having said that, the Magnaflow version is a direct bolt-up, or so they claim. Since California converters have to be OBD-II compliant, and you have a pre-OBD II car there may be a “downstream” air/fuel sensor hole. (If so, just plug it.)

The cats are the same between the 2.5L and 4.0L.

Magnaflow universal fit p/n 39005
Magnaflow direct fit p/n 39229

Good luck!! Post the outcome please…

 

I'd get a fresh tank of fuel without any seafoam in it and try again.

 

get a non-CA cat shipped to a friend somewhere else to send to you here. When your car was made, they used the same cat 50 states, so the 49 state cat is plenty good for your vehicle. That law is the biggest joke ever

 

So, update on my smog issue . . .
I welded in a catalytic converter I had on my toyota rockcrawler for less than 5000 miles and it failed even worse!

I had a few problems though:
1. Found out the catalytic converter is too far back in the exhaust stream, guy said it wasn't even heating up correctly.
2. I'm missing my fan shroud, which I should've realized earlier definitely isn't helping keep my engine cool.

I'll correct these and try again, got a 2 month extension from DMV in the meantime.

Question: Blasto, you said that california catalytic converters have to be OBDII compliant. Does this apply to me since I have a '91 cherokee?
Should I just go ahead and order an OBDII compliant one anyway? It'll probably make my emissions look better.

 

Theoretically it does have to be a California compliant converter, which by default are all OBD-II. But a 49-state converter should allow you to pass the tailpipe test even if it's not purely legal by statute.

The stock setup DOES put the converter very far back in the exhaust stream for some reason (on my '89 it's mounted aft of the transmission crossmember). Moving it closer to the exhaust manifold should help it come up to temp quicker and increase its efficiency. Alternatively you can wrap exhaust insulation around the manifold and piping leading to the converter. Having said that, I wouldn't trust a random smog tech saying that your catalyst isn't heating up properly unless he's actually measured its temperature. (He may be right, but on the other hand, he's just guessing.)

Post your emissions numbers if you have 'em handy. It will help with the diagnosis. :-)

 

FAILED AGAIN!! GRR!
This time I did just fine one my HC and CO because I put in a new magnaflow universal catalytic converter, my NO is waaay high though.
I believe that I might be running lean since I just replaced spark plugs, put a fan shroud on it, and I've got plenty of coolant and a new thermostat.

I read that very low CO readings (which I have) may indicate a lean mixture. Here's what I've got, what do you think?

 

Any luck at passing smog on your jeep? Im having the same problem NO to high.

 

I am so glad I don't live in that state anymore...just for that expensive reason.

NM = no standards...whatsoever

 

California does not follow OBDII standards, they have their own CARB standard. A universal converter runs about $150 - 175 delivered. To my knowledge MagnaFlow makes the only CARB legal aftermarket converters.

As of early last year (I think it was) all vehicles in CA must use a CARB legal converter no matter what year the vehicle is.

 

I bought the MagnaFlow direct fit from oreillyauto.com and that did the final trick for me. My o2 had gone bad and caused my jeep to run rich and THAT ruined my old cat. Also in California, there is a visual inspection by the tester because he needs to verify that the cat has the California metal stamp (to verify a LEGAL cat is being used).

Be sure to reset your ECU after replacing the o2 and your cat. Otherwise, your jeep will still fail because the ECM is using the last o2 sensor readings. Disconnect the positive cable from your battery. Then ground the positive cable to the negative cable for 30 seconds to discharge any remaining charge in the capacitors. Connect the positive cable back on to the battery. Then turn your ignition to ON (but do not crank the engine). Turn on the headlights. Then turn off the headlights. Now turn the key to off.