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Old 09-25-2003, 07:03 AM
BobK BobK is offline
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Join Date: Nov 2001
Location: North Central Kentucky
Posts: 1,065
My '86 190E 2.3 failed HC a few years ago. Came in around 244ppm, limit was 220. Did bunch of stuff including cap, rotor, wires, O2 sensor, oil change, plugs, air filter. After a couple of tries, replacing some parts each time. Finally passed with a HC of 167ppm. Year later had to go thru again (since I was soooo bad last time), passed with a 66ppm. I had done NOTHING different. No tune-up or other parts. Just oil change. Did have a slight exhaust leak after the cat but forward of muffler. Maybe it was pulling in fresh air at the leak. My own opinion is that your results are more related to the phase of the moon, the T-bill rate, which rerun is on tv tonight, etc. Truth be told, cat is probably about shot. If I have to replace the cat, I'll probably get a whole exhaust system from Time-Valve and put it on myself.
Funny thing on your readings was the CO. That says too much fuel/not enough air. Dirty air filter and bad O2 sensor probably first things to check. If the O2 sensor is old, just replace it. They age and go bad. Sensor is not too hard to replace. Connector is under carpet on passenger side of floor pan near front edge of seat as I recall. If the sensor was bad, you may want to take the car out for an extended run in maybe Montana or somewhere you can do an "Italian tune-up" to see if you can burn off some of the crud in the cat. BTW, do the car burn much oil? that can put the numbers thru the roof.
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