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#1
01-08-2003, 06:51 PM
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Screwed Again by Wayward Woman!
Took WW back for an emissions re-test today. Since my normal place's machine was down, I ended up with a gung-ho tech who insisted that I needed the 15/20 mph dyno test instead of the idle/2500 RPM test that was done previously. Since it was the idle I was worried about, I went ahead. Big mistake.
Results. Test - Limit/Reading - 15 mph 25 mph HC ppm - 144/135 pass 140/176 fail CO% - 1.34/.45 pass 1.73/.59 pass NO ppm - 1077/1746 fail 984/2104 fail So, it looks like I have some more work to do. From what I have learned, I am probably set too lean causing the low CO but high NO. I will probably have to find out why the air pump is not coming on. I do wonder about the one high HC reading though.
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Chuck Taylor Falls Church VA '66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe 
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#2
01-08-2003, 07:20 PM
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Chuck:
You don't have proper mixture control yet. Missfire will cause all sorts of trouble with the O2 sensor, since it reads oxygen, not HC! What happens is that the O2 sensor sees "lean" when you have a miss, since the oxygen didn't get burned, so it adds more fuel, and off you go. It can also oscillate back and forth, cause low power and excessive knock, all sorts of crap. You also need to make sure you have good fuel supply -- if the supply pressure is low, you have not be able to get the feedback system to control the mixture since it can never get enough fuel -- if it goes lean at high load, you get misfire, burned plugs, and so forth. Is your ignition in tip-top shape? The system Benz uses will run long past the time you need new cap, rotor, and wires! Air pump failure to operate (assuming the pump itself is OK) is a vacuum problem, or a failed diverter valve (cuts the air off under coast so you don't blow the muffler up) -- if it sticks open, you will get high HC at load. Peter
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1972 220D ?? miles 1988 300E 200,012 1987 300D Turbo killed 9/25/07, 275,000 miles 1985 Volvo 740 GLE Turobodiesel 218,000 1972 280 SE 4.5 165, 000 - It runs!
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#3
01-08-2003, 09:55 PM
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I agree. I am going to replace the cap, rotor, and wires and turn it over to someone with a tri-gas analyzer, the other needed instruments, and more experience. I have gone as far as I can with my DMM and dwell meter.
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Chuck Taylor Falls Church VA '66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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#4
01-09-2003, 12:20 PM
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Looks like your numbers are getting better. Be sure to have it hot, hot, hot when you get tested after the next round of repairs and tweaks. An hour on the highway should be fine.
Also, the air pump only run for a few minutes after start-up or does WW have an older air injection system that runs full time? I don't know because my two bracket WW (older & newer).
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Mike Tangas '73 280SEL 4.5 (9/72)- RIP  Only 8,173 units built from 5/71 thru 11/72 '02 CLK320 Cabriolet - wifey's mid-life crisis 2012 VW Jetta Sportwagon TDI...at least its a diesel Non illegitemae carborundum.
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#5
01-09-2003, 12:26 PM
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What about those liquid emission-control system cleaners I see in auto parts stores?
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