how to decrease hydrocarbons?

[240meowth]

So yah, I realized something... People w/ SR usually don't run cat... BOOOO, the earth is dieing!!! Put a high-flow cat in or something.

So than I reaized, I bearly passed my emmissions last time, due to hydrocarbons. What is hydrocarbons and what causes them? Maybe I need a new cat?

I'm clueless, help me someone

[Blues13]

I think the richer you're running, the higher your HCs are.. the cat mainly helps with the NOx levels. You should do a search, I remember seeing this somewhere as well..

[Var]

HC or HydroCarbons are raw and unburned gas. basically you engine didnt use it up. It could be fixed as easily as an air filter if you need one or maybe a tune up. Every car has different problems and it would be impossible for anyone to specifically tell you why your car is running rich. Plus if you live in California passing even barely is good enough cause our laws are so strict.

[S13Nissan240SX]

I often times have difficulty passing emissions. Sometimes it takes me two or three attempts before I'll get through. It's a hastle but in that time I've seen that, at least with my car, I can have a real high hydrocarbon reading one day, and then change a few things, and get it super low the next. So you don't necessarily need to be making serious changes. You might have to, but I never have. Usually giving the car a tune up and cleaning my MAFS is enough to get it back in line. You can also buy a fuel additive at any auto parts store to lower your hydrocarbon emissions. Those may work.

Good luck,
Matt

[mrmephistopheles]

having an EGR that works also helps. :D

[Bolo]

You can try using hotter spark plugs. Did that with an sr and passed easily.

[goodjuan]

aquamist jeremy.....instead of dumping unburnt fuel as coolant, use water and run learner. oh wait...is this NA? or turbo?

[Var]

Originally posted by mrmephistopheles
having an EGR that works also helps. :D

No it doesn't. The sole purpose of the EGR valve is to reduce NOx emissions.