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Stock mj just failed smog twice...

xcm

xcm

NAXJA Forum User
Location
Southern Oregon
SOOO..... my fathers 90 mj, which has remarkedly remained stock, just failed smog for the 50th time... this time it failed emmissions, 3 weekends ago it failed the newest emmisions test, the pressure test.

this time, failed emmissions, went over on HC and CO... can someone recommend where to start? weve been having tons of small BS problems with this truck... and were trying to get it back on the road.

camera phone sucks too much to post the actual numbers, but she measured:

hc: 124@15mph (max was 122), and 110@25mph (limit 102) both over limit...
CO%: 2.44 at 15mph! putting us in GROSSPOLUTER territory.... and 2.35@25mph... also in GP territory....

thing is, is it passed emissions 2 weeks ago..... but failed the new evap pressure test, now we fixed the fuel problem and it failed.... is rain enough to do this, or did we mess something up?

btw, anyone seen similar mj models? ie the gt3 submodel? dealer option? or what?
mj2gq3.jpg

mj3jj2.jpg
 
Make sure you have a good cat, and also check the oxy sensor. Change the plugs and check the resistance on the plug wires is good.

Also run a can of seafoam thru just before you smog it. Make sure that is does not have any vaccuum leaaks.

My son smogged his and was in the same boat, change everything to new and passed better than a new car.

Just my .02 cents worth.

Leep
 
I do a new o2 sensor before I smog every time, and have always come through with retardedly low numbers.
 
seafoam is embarassing, but i guess i have no options. do you mean thru the fuel, or thru the vacuum system?
looking through the 4.0 mpfi manual, it appears i need a code scanner to check the o2.... autozone shows it as $50, so we'll replace that...
is there a way to check the CAT? my manual doesnt cover that =\\
thanks for your help
btw, this thing does have one hell of a exhaust header leak, would that mess up the o2 even more?
 
you cant use a code scanner on a 1990 mj.. they arent obd.

If you can't remember the last time you replaced the o2 sensor, its probably time to do it now. You can get them for about $50 at autozone, in bosch brand.
 
Yes the leaky manifold will have affects. Run 3/4 the seafoam thru the vac system and toss the rest in the tank. How many miles are on it with the cat ? If you cannot remember the cat being changed then that prob needs to be done as well.

I just changed the one on my YJ. sounded like a rock rolling around inside it. Also check the other things that I mentioned earlier. The high HC level is caused from unburned fuel.
 
I put in some good quality gas (mid grade) mobil and a bottle of lucas fuel teatment in 2 days before. The day of make sure to keep the jeep running while your waiting for them to bring it in. From what I have heard it creates the most pollution at and just after start up. Do also check plugs and cat my cat was jacked up but I was still able to pass, what ever was wrong with it was causing it to run hot. Good luck
 
yeah... i now feel embarassed.... as far as ive known, this thing hasnt ever had a new cat OR o2 sensor.... and it used to deliver news papers during the night, and volvo parts all day...... these things will be changed asap....
and the wires check to make sure i didnt get a bad wire... ( just did a tune up, incl. new wires)
which reminds me, i need a good multimeter...

so to recap...
-new cat
-new 02
-check wires with my new skills aquired from http://www.allaboutcircuits.com/vol_1/chpt_3/9.html
-seafoam

RETEST (warm, with a running start)!

good to go
thanks for not letting the tech in socal forum thing stop you from helping a guy out.... thanks again
 
Last edited:
i had a bad cat and failed with almost the exact same numbers. change the cat. i can get you one for 113$ plus tax through my work.
 
think I paid 60 for a semi oem cat at kragen. Looked just like the one that was on there. over a year installed no probs.
 
In the cat? more than likely the name and the store.
 
I picked up a 2.5" magnaflow high flow CAT off ebay for $41 shipped. Just get a universal with the right engine size and have it welded on. If you do the ebay thing, look for the auctions that say "Best Offer" and make them an offer. Thats how I got mine so cheap.
 
silverslk said:
I picked up a 2.5" magnaflow high flow CAT off ebay for $41 shipped. Just get a universal with the right engine size and have it welded on. If you do the ebay thing, look for the auctions that say "Best Offer" and make them an offer. Thats how I got mine so cheap.
Click to expand...


Have you smogged it yet with your new high flow CAT? Some high flow units say they are not California legal but I've heard they will still pass smog.
 
i meant the $50 o2 sensor... wondering what the differance between that and the $113 one grimm mentioned...

i assume a muffler shop have cats in stock?
 
I thought grimm was talking about a cat.

autozone tends to be cheaper than napa on electrical stuff, and his parts come from napa. He has a great deal on dana/spicer parts though!
 
praetorian said:
Have you smogged it yet with your new high flow CAT? Some high flow units say they are not California legal but I've heard they will still pass smog.
Click to expand...
Depends on the smog station. Last time I got mine smogged the guy was saying that I didn't have a cat. I had one of these:
http://cgi.ebay.com/ebaymotors/59959-Magnaflow-Metallic-Catalytic-Cat-Converter-3_W0QQitemZ150209096815QQcmdZViewItem?hash=item150209096815
I had to convince the guy that it was a cat. He passed me.
 
it is a test only smog... not that i know what that means, and allthough i think i know where this is going, palm springs is waay to far to drive on expired tags...

oh. and after re-reading it, grimm IS talking about the cat....
 
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