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Old 10-03-2002, 08:14 AM
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FAILED Inspection HELP!

The first time I took my 87' 420SEL to New Jersey inspection I had a bit of a smoke problem and failed inspection. I had the stem seals replaced and it the car didn't smoke anymore! This morning I took the car back for inspection and it FAILED for emissions. I have no idea what these numbers mean but maybe sombody will?

The HC standard is 134 and my car was puttin out 355.
The CO% standard is 0.75 and it tested at 8.64.

What do I do? O2 censor?
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Old 10-03-2002, 09:42 AM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
The HIGH CO% reading is the real problem. Either the O2 sensor isn't working at all or someone has mis-adjusted the fuel mixture.
Checking the DUTY cycle should reveal the problem!
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Old 10-03-2002, 12:44 PM
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Join Date: Jul 2002
Location: Cleveland, OH
Posts: 22
My 260e failed OH emmisions . It had been sitting for a few months - so that was part of the problem. The other was the O2 sensor was bad.

I replaced the O2 sensor and drove the car up and down I-90 real fast for about an hour before taking it to be tested. The retest numbers passed - and were drastically lower than those of the failed test.

I don't know if you want to do this on your Mercedes - but when I was in college and my '82 Buick failed PA emmisions, I ran the tank almost empty and then loaded it up with that stuff used to prevent fuel line freeze-up - which I suspect is ethanol. (I got about 5 bottles of it real cheap in the spring when Big Lots was having clearance sale.) Since I was burning mostly ethanol, the CO emmisssions dropped as did HC levels. It passed. Who knows what it did to the engine - and who cares? After all, it was a 1982 Buick Skylark.
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Old 10-03-2002, 05:38 PM
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Join Date: Jul 2002
Location: Middletown, DE
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I used the guaranteed "decarbonizer" from RCR for $6.00 on my Grand Wag. I failed inspection 2 years ago, passed this one WAY below standards (had the HC problem at idle).
1985 190D 2.2l Sold-to Brother-in-law
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Old 10-04-2002, 03:23 AM
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Thanks for the help guys. I have a question about the O2 sensor. If the sensor wasn't working wouldn't it set off one of the idiot lights on the dash?
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Old 10-04-2002, 08:58 AM
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Join Date: Jul 2002
Location: Cleveland, OH
Posts: 22
Concerning the O2 sensor - I don't think there is a system alert when they go bad. At least not on my 260e.


I just got rid of my '91 GW. I didn't have room for it (and you know it needs lots of room - has a big appetite too!) I gave it to my father so I would still have access to it for camping, hauling, drive-in movies, and all the other things that it is so great for. There is still no SUV on the market as practical.
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