need help diagnosing emissions problem

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need help diagnosing emissions problem

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need help diagnosing emissions problem - 6/8/2006 11:45:35 AM

96accent

Posts: 1
Joined: 6/8/2006
Status: offline

History:
My 96 Accent misfired aprox 1.5 yrs ago due to a bad plug wire. This damaged my upstream O2 sensor. I immediately replaced the wires, but drove the car for several months until replacing the sensor (used a Bosch universal). Running rich and / or old high milage caused by my cat to fail. So I replaced the cat (used an OE direct fit from the internet) immediately after replacing the sensor.

At the end of last year, I took my car to the dealer to replace suspension parts (factory recall). Aprox 10mi later my check engine light came on for downstream O2 sensor malfunction and upstream O2 sensor slow response (same time). I replaced the downstream sensor (OE type installed by garage) thinking it was due to high mileage and / or running rich during my last problem. Then cleared the codes, thinking the upstream O2 sensor slow response was due to the downstream sensor malfunction (readings not in sync).

Less than 100mi later the upstream O2 sensor slow response code reappeared. I talked to people and heard some say they had problems with a universal O2 sensor within a year (specifically with import vehicles). So I replaced the upstream O2 sensor with one from a Hyundai dealer, and cleared the code.

About 180 miles later, my check engine light came on for catalyst efficient below threshold, and returns even sooner after reseting the code. My cat is aprox 1 year / 12k miles old. My car idles fine, drives fine, and only burns .5qts or so of oil between changes (144k miles on car). I still get mid to high 30's (mi per gal). The only other symptom I found was a little oil around the fresh air hose connection to my manifold. This was a few months ago. I immediately checked the hoses and replaced the PVC valve. There doesn't seem to be any more oil coming out.

Anybody think something other than the cat is not working right? I'm trying to save $$$ by troubleshooting as much as I can. Thanks for staying awake!

P.S. Years ago, the Hyundai dealer I mentioned above tried charging me $300 for something that didn't need to be replaced. I confirmed what really needed to be repaired with two other places, took care of the problem myself, and got the car inspected. Anybody think they did something bad to my car during my recall visit, so I would return to pay for repairs?