my luck. the gas station in new york that inspected my car ...94 E320 failed me and then had no clue how to fix the problem. so I had it looked at another place....he couldn't do it either but he did offer sound advice. first of all my car at idle revs fluctuates 5-10 but only in the park position. this is somewhat related to EXHAUST EMMISIONS. the vehicle reading reports hydocarbons at 411 ppm and test limits are 220..... co 5.53% vs. 1.20%....co2 12.0 and nox 2%. i might need a new idle speed control unit. i have an appointment with the benz dealer later this week. since the car is not under warranty and i'll be paying out of my pocket i need to make sure that i won't pay for excessive costly repairs.
any suggestions..im glad this site is hear to help. I just want to be prepared. what the heck is that smell!!!!

Happy New Year!!
Thanks,
Ron

First thing that I would do is give the car a very thorough tuneup. Those figures indicate an excessively rich mixture. Pull the plugs, replace them, new wires, change oil, replace air filter, check PCV valve. Check engine light on? A defective 02 sensor can also cause an excessively rich condition. I would check the cheap stuff before buying the expensive stuff.

This has got to be excessively rich mixture. On a 94 E320, it means the computer is not able to adjust the mixture at all. I had the EXACT same problem on my car (85 190E 2.3), and it turned out to be the O2 sensor - get it fixed ASAP, otherwise you'll ruin the cat convertor. with a new sensor, my HC went down from 142 ppm to 22 ppm, CO went down from about 4.5% to 0.13%.

Thanks all for your inputs. The mercedes dealer diagnosed the problem and found that I need a new air mass sensor. The cost new after shopping around is anywhere between $220 and $300.
It should take not more than 1 hour to replace and test.
Thumbs down for silver star in queens ny.
Rheinland Motors is where the service is getting done.

thanks for all the advice. I need an 02 sensor in addition to the air mass sensor. your all correct!!