Unburned hydrocarbons usually indicates incomplete combustion generally caused by a breakdown in the ignition system meaning YOU NEED A COMPLETE TUNE-UP. If you don't know when these parts were last changed then replace the following: Spark Plugs Ignition Wires Distributer cap and Rotor Fuel filter Oil filter and engine oil Air filter If replacing these parts doesn't get you to pass then you will have to find a shop that can adjust the mixture screw in the metering unit after making sure there are no vacuum leaks. Since you are at 30,000 then you should also change the O2 sensor and adjust the valves but I don't think that is what is failing as the sensor usually will last longer than 30,000, that is just the interval that the EPA decided to replace them at BEFORE they go bad! Of course 1 tank of leaded fuel can kill the sensor AND foul the CAT. David Teitelbaum vin 10757 --- In dmcnews@xxxx, "tmpintnl" <tobyp@xxxx> wrote: > Rendy - I don't believe that the catalytic converter would be involved > in high hydrocarbons. If the O2 sensor has failed, the fuel injection > defaults to a rich condition to avoid damage from detonation. Also, > if the frequency valve fails, the same is true. Or, you could have a > cold start valve gone mad, and dumping fuel at all times. High > hydrocarbons indicate an overly rich mixture, so fuel system failures > or misadjustments would be where to start. Another possible source > could be simply that your car needs a tune up, with fresh plugs, > wires, cap, etc. If you have a cylinder that isn't firing > consistently, the unburned fuel will result in high apparent > hydrocarbons. Any other thoughts from the rest of you? > > Toby Peterson VIN 2248 > Winged1 > > --- In dmcnews@xxxx, Rendy Cheng <rpcheng@xxxx> wrote: > > > Yesterday, my Delorean failed the smog check due to high > hydrocarbon. The technician played the rpm little bit but it did not > lower the hydrocarbon.