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A challenge for my Mercedes friends :-)
Holy Cow! My 1994 c220 (141 KMiles) has just passed California Smog Check II with flying colors at a test-only smog station. The results are virtually perfect. I believe new ultra-low emission vehicles like Honda Civic hybrid, Toyota Prius etc. cannot even get such perfect results. Since I was required to take the car to a test-only smog station, I did quite a few preparations for it before the smog check:
- Brand new Bosch MAF (the hybrid electronic circuit of the old MAF is bad, so cleaning the thin-film element didn't help ). - 2 brand new universal NTK oxygen sensors (the old pre-cat O2S had slow signal response and the old post-cat O2S had bad heater circuit). Total price for both new O2S is just $35! If I buy the OEM ones, it would set me back about $300. - 4 brand new Bosch non-resistor spark plugs. - Change new rubber connectors to make sure there's no vacuum leak. Also verify that fuel pressure regulator and the EGR work. - Reset the HFM-sfi ECU. - Fresh oil change. - A 5 minutes highway run ==================================== At 15 mph (RPM=1498): MEAS MAX AVERAGE ------------------------------------------------------- %CO2 15.7 N/A N/A ------------------------------------------------------- %O2 0.0 N/A N/A -------------------------------------------------------- HC(ppm) 1 85 21 -------------------------------------------------------- %CO 0.0 0.5 0.06 ------------------------------------------------------ NO (ppm) 1 695 150 ------------------------------------------------------- ==================================== At 25 mph (RPM=1594): MEAS MAX AVERAGE ------------------------------------------------------- %CO2 15.7 N/A N/A ------------------------------------------------------- %O2 0.0 N/A N/A -------------------------------------------------------- HC(ppm) 1 50 13 -------------------------------------------------------- %CO 0.0 0.47 0.05 ------------------------------------------------------- NO (ppm) 3 717 136 ------------------------------------------------------- ==================================== Legend: MEAS = Measured results on my 1994 c220 MAX = Maximum Allowable Emissions AVERAGE = Average Emissions for Passing Vehicles ==================================== Let's see who can beat my car's smog check results :-) CA DMV should exempt my car from smog check for 10 years :-) My warmest thanks to Mr. Arthur Dalton, Mr. Steve Brotherton and Mr. M.B.DOC! I learned a quite lot about Mercedes engine management, fuel trim behavior and emission control pecularities as well as excellent ECU tricks thanks to you. Best regards, Eric |
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Excellent results and it shows the benefits of proper maintenance. When the ECU has good signals, it's able to do its job.
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Regards Warren Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL ENTER > = (HP RPN) Not part of the in-crowd since 1952. |
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