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1995 Plymouth Neon failed smog with high Hydrocarbon HC levels.

My car has over 150,000 miles and typically runs well. It failed smog with high HC Hydrocarbon levels, and my friend says that a tune-up will likely fix the problem. If I do this, and go in for another smog and fail again, what happens?
Answer:

Hydrocarbon (HC) is basically raw fuel (gasoline). The number one cause a car will produce high HC is a defective ignition system. During the combustion process any number of engine conditions can cause high Hydrocarbons. Sparkplugs and spark wires are constantly exposed to high temperatures and high voltages. You must ensure your engine's ignition system is functioning properly, by inspecting all the sparkplugs and their wires. If any of the plugs look worn out or have excessive carbon build-up you must replace them. The distributor cap should also be inspected for cracks or excessive carbon deposits. If it appears that the cap may be faulty, you will need to replace it as well. Assuming all other emissions measurements are within limits; CO, NOx, O2 and CO2, your vehicle's HC fault will be fixed with an inspection and replacement of the ignition sparkplugs, wires, distributor cap and rotor. The ignition coil should be the last component in the ignition system to require replacement, however its inspection will be required as well. posted by SmogTips Support

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