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Old 03-06-2013, 04:05 PM   #1
Juju3's Avatar
Join Date: Mar 2013
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Failed smog

I just took my 88 YJ in for smog test and it was not good. The guy said its running rich, possible exhaust leak, incorrect air/gas ratio, maybe cat is bad, etc.. Had me flustered. Can anyone give me some advice on what I should be looking at or where should I start trouble shooting??

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Old 03-06-2013, 05:58 PM   #2
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Dirty air filter, bad combustion because of bad ignition, bad cats, and bad timing are all examples of maybes, most of the potential problems, assuming you do not have an exhaust leak (Vacuum leaks result in high O2 in the exhaust and are usually obvious to inspectors) can be fixed with a good tuneup.

Get new wires, plugs, rotor, cap, check timing, clean air filter, and retest.

When was the last time it was tuned up?

95 Wrangler 2.5L 31x10.5s 5 speed.
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Old 03-06-2013, 09:40 PM   #3

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FREE Smog Check Coupons | Get 50% Off CA Smog Test Centers | Smog Check, Smog Test Only Center, Smog Repair Stations, Smog Station, Emission Support Website. Find smog test, STAR smog stations, smog test center, smog check repair, auto repair shop di

Great link and if you look around a little you will find a full description of everything related to smog testing and what makes everything work and how to pass. It worked for me.
89 2.5 TBI, 4" RC lift, 1" Booms, SYE, Adams Driveshafts front and rear, Ford 8.8 with 4:88s, BFG 33X12.50X15, and a ton of other stuff.

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Old 03-06-2013, 11:27 PM   #4
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I was underneath my jeep today trying to change out the O2 sensor and I think I found the problem to why it failed the smog test. I have a crack on my exhaust manifold. Any suggestion on how to repair this or do I need to completely change it out? If so what is a reasonable price for a mechanic to do the work and how long should it take? Ant tips would be appreciated. Thanks
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Old 03-07-2013, 02:47 PM   #5
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You simply need to get a new exhaust manifold, and manifold gasket.

Can't speak of any reasonable charge on replacing it, as I did my own in my driveway. Not that difficult of a job, just takes some time.
1990 Wrangler 4.2L
Howell TBI, 2.5" OME springs; OME Nitroshocks; 5/8" OME shackles; Swaybar discos; 31" tires/15" rims
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Old 03-15-2013, 11:11 AM   #6
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Well I finally passed smog!! After replacing exhaust manifold, repairing a cracked intake, replacing cat converter, gas tank vacuum line. I knew I was buying an old jeep and expected to spend some money so I guess now its time to enjoy some sun. Thanks everyone for your suggestions.

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