how can I reduce hydrocarbons (high and low speed) for a california smog test?

Answer 1

If your car failed the ASM California test with elevated HC, it is best to perform proper diagnostics to identify the cause, then repair the cause.
Assuming that your car in fuel injected, here is a list of POSSIBLE failures --
1) Vacuum leaks
2) Excessive advanced ignition timing
3) A MAP or MAF sensor slightly out of spec. voltage
4) Excessive engine coolant temp
5) EGR valve pintle stuck open
6) Restricted fuel filter
7) Failing fuel pump
8) Failing fuel pressure regulator
9) Sleepy, lazy or otherwise failing oxygen sensor.
10) Contaminated engine oil
11) PCV valve in need of service.
12) Failed or deteriorating catalytic converter

There are many other items, but they are generally related to the above list.
It is money saved to take the car to a LICENSED emissions repair and test facility, and ask that they run a diagnostic routine for the elevated hydrocarbons. Take the failure report so that he can look to see what he is chasing.
Most shops will perform this task for about an hour's worth of shop time. The repairs will be on top of the diagnostics.
One of the things that the tech can do with the report is to calculate the "LAMBDA" factor. This will tell him if the engine is in good fuel control or not, and if the primary cause is in the fuel control or if it is in the catalytic converter.
If you believe you are being taken advantage of, call the Bureau of Automotive Repair at [phone] and ask that they investigate. This is your tax dollars at work. Use them.
In the mean time, if you are trying to get the license renewed, pay the fees. It is the State of California, they will take the money! That will stop the penalties at DMV. You won't get a sticker, but you will be paid up. Ask for an extension for driving. This will get you about 90 days more to make the repairs and pass the emissions test, or make the decision to trade the car in for something else.

Good Luck

Answer 2

A high level of hydrocarbons may be caused by a number of things such as excessive oil consumption, bad catalytic converter, bad oxygen sensor, bad EGR valve (although a bad EGR would lead to high levels of NOx, it is still possible for it to cause high levels of Hc)
Also, if this car is carbureated instead of fuel injected, you might need to have the carburetor adjusted. I would also recommend having your Mass Air Flow sensor checked out, as well as your Oxygen sensors. These are areas that when bad, cause high levels of Hydrocarbons to occur.

Answer 3

first try an intake and injection cleaning. this needs to be done about once a year to remove the carbon buildup in the intake. when this accummulates, it makes the car burn more gas to make up for the blockage, thus raising the hydrocarbons in the exhaust. ive done tailpipe emissions test for a few years and this is what ive seen and what ive read up on. hope this helps

Answer 4

Plugged EGR port, or defective knock sensor. extra: particularly, that would reason greater NOX (nitrous oxide) readings. severe hydrocarbons is detrimental combustion. Low gasoline pump tension? grimy air filter out? detrimental gasoline high quality? low compression?

Answer 5

one other thing that you can do is get the oil changed just before the test

Answer 6

take the vehicle and drop it off at the junk yard.