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?

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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MERCEDES Benz Master Guild Technician (6 TIMES)
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190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

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.

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).

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1985 190D 2.2l Sold-to Brother-in-law
1996 Mustang 3.8l -"thinks it's a sports car"
1988 Grand Wagoneer - Sold (good home)
1995 Grand Cherokee Ltd -"What was I thinking??!!"

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?

Concerning the O2 sensor - I don't think there is a system alert when they go bad. At least not on my 260e.

Piotr:

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.