To change ownership the car must have been smogged within the last 90 days. According to law a seller is required to smog the car before sale. Your friend is legally liable for that car to pass smog before he sells it. Since he is your friend, we won't go there. HC means unburnt fuel. Adjusting CO won't help that much. You need to find the reason all the fuel isn't burning. Plugs, cap, wires, vacuum leak. Can you provide all before and after readings? That car is on the state's list for high emitter profile, but for NOX and not HC.

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