1991 Mercedes Benz 500sl Repair Question
How to find problem causing such high hc readings, cauling failure of emission testing
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.
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Could be an ignition misfire, lean misfire and low compression
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