how to find problem causing such high HC readings, cauling failure of emission testing

1991 MERCEDES BENZ 500SL
85,000 MILES
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CAPTAINKIRK
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idle is rough and at 2500 rpm engine has 900 ppm HC and you can hear and feel the miss. new pluges instaled.
Sep 2, 2011 at 10:09 PM
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WRENCHTECH
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You've pretty much answered your own question. HC is basically unburned fuel, usually caused by incomplete combustion and a misfire is exactly that. You need to locate and resolve the misfire issue. Look first at plugs, wires, injectors, etc.
Sep 2, 2011 at 10:34 PM
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RASMATAZ
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Could be an ignition misfire, lean misfire and low compression
Sep 2, 2011 at 10:44 PM
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