I have just purchased a 190E 2.3 (1987)MB. Except for its high mileage (some 239,800 original miles, I think), this car is in excellent condition with all working electronic features (even the clock!) However, it failed the emissions test three times. The emissions test diagnostic results indicated that HC is the problem (some 1.98 gram/mile, and the limit is 0.8 gram/mile) I have replaced spark plugs, air and oil filters,and the works. The latest replacement was an oxygen sensor, but to no avail. I am going nuts here trying to figure out what can be done, without spending my kid's college fund, on this problem. High HC seems to be the main problem with the test. Do you have any suggestions? Thanks a bunch!

C.B.

Take a look at the report and give me the numbers for HC, CO, NO, CO2

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Benzmac:
ASE CERTIFIED MASTER AUTO TECHNICIAN
LEAD TECHNICIAN FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Thanks for getting to me so quickly! The test results are as follows:

Emissions
(I/M 240) Reading Unit Limit P/F

HC 1.9714 gram/mile 0.8000 Fail
CO 9.9615 gram/mile 15.000 Pass
NOx 4.1625 gram/mile N/A N/A
CO2 N/A N/A N/A

High HC readings are the result of un-burnt fuel, usually from ignition system problems. First when a engine has high mileage have the compression tested to make sure that engine is in good working order. If that checks out O.K. then consentrate on the ignition system, any slight misfire wil cause the high H.C. readings that the car has.
If the engine is burning oil this will raise the HC reading also. Sometimes changing the oil will help(fuel in the oil).