Re: high hydrocarbon in exhaust

["jtrealtywebspannet" <jtrealty@xxxx>]

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.