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CA Smog help

I am running the original Cat but it shows no signs of clogging that I can tell. The O2 sensor was replaced four years ago.

88XJ 4.0 non HO 180K miles or so. New wires, cap, distributor. Fresh oil change. New Air Filter. I had a friends shop put the smog sniffer on it. He says my CO is at 135. It should be less than 100 according to him. After doing some research the numbers don't match up to what I am reading. There are no CO numbers anything like that anywhere. I also need to go to a test only. This is the first year they ever made me do that. Does anyone know of a few things to try before I send it to someone to take all my money? I only have until the 8th of December. Anyone know of a reliable shop who can fix it if I cant? I haven't changed the plugs in a while (30k miles maybe? don't), I will do that for good measure. I am running the original Cat but it shows no signs of clogging that I can tell. The O2 sensor was replaced four years ago.

Would 89 octane help or hurt the process. Someone also mentioned an additive product once. KH

Reply to
Kevin in San Diego
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Reply to
L.W.(ßill)

It may be just smoke and mirrors, but I replaced the cat on my 88 MJ (160K on the 4.0L) and the CO numbers took a real dive. There was no visible sign of plugging. Also, 4 years on an O2 sensor - depending on the milage - may be a little long with that many miles on the engine. Even if you don't use much oil (I change oil at a quart down or 4K miles, whichever comes first) you are still passing a lot of crap with 150K+ on the engine.

I replaced the O2 sensor a couple of years back and it did wonders for the idle (and the color of the tailpipe ) then replaced the cat on speculation this year as I felt that the top end and highway performance had deteriorated. I did get a noticable improvement so the cat was probably plugged a bit.

New plugs, a fresh oil change, and a clean air filter will help keep the sniffer happy > I am running the original Cat but it shows no signs of clogging that I can

Reply to
Will Honea

Thanks guys. I will throw a few parts at it and let you know. KH

Reply to
Kevin in San Diego

My guess is your friend is confusing CO and HC. The number you posted looks more like HC. HC is measured in PPM. CO is measured in percent.

Catalytic converters do wear out, and 180k is a lot of miles. It's been my experience that HC numbers are usually the first to get up over the pass/fail cutoff as the cat gets older. Nothing scientific about my findings, that just seems to be the way it goes most of the time.

O2 sensor failure is also pretty common. A good one will switch quickly between

0 and 5 volts.

Messing with octane *may* help *slightly* with a NOx problem, but will be no help to you if you indeed have a HC problem.

A fresh tune couldn't hurt.

Reply to
bllsht

Reply to
Kevin in San Diego

It turns out my O2 sensor was busted. The ceramic was broken and the wires were just hanging!. I popped a new one in and it passed! KH

Reply to
Kevin in San Diego

Reply to
L.W.(ßill)

I bet, my mileage has been horrible but I regeared this year and attributed it to that. KH

Reply to
Kevin in San Diego

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