TRIPOWER

help me--
95 z28 shorty headers, random cat, madz tune, 114xxx miles.

i failed in the hydro carbons
standard 0.80
my readings 1.90
i passed my co test. i waited for 25 min before i was tested. do you think that was the problem? what should i do?
i live in the greater chicago area in dupage co.

Vigilante

From what I have been told, a high HC level is the sign of a spark problem. Maybe check to see if any of your plug wires got burnt on your headers. I was having a similar problem (only failing because of HCs) and it turned out that my cat was empty and I had several bad plug wires. Good luck though.

FastZinTennessee

I passed emmissions here in TN without a catalytic converter. They apparently measure hydrocarbons differently here than they do for your test. Max allowable was 220 PPM (parts per million) and my reading was 132.

Also if it helps my carbon monoxide reading was .25% with a max allowable of 1.20%.

If there aren't any codes to scan I would start with the basics- plugs/wires, check the air filter to make sure it's not really dirty. You can use some good fuel system cleaner, possibly even change the oxygen sensors. I'm not a big fan of just throwing parts at a problem, so if you can scan it try that first.

TRIPOWER

no codes found. i had a plugs , wires, and a new opti in april 05. i think it has to do with my tune the temp may be to low for emissions.

FastZinTennessee

What temp is your thermostat?

96flame

I passed in Ontario with 20 hyrocarbons with a 160 stat. Hydrocarbons are unburnt fuel. Oxygen sensors have a big effect on that but usually CO would also be high what was your CO reading?

OBE1 95Z28

You want both the engine and cat(s) fully warmed up before the test. If they were cold from sitting for 25 minutes that wouldn't help.

SLeePer350

Speaking from an academic point of view....left over HC (hydrocarbons) are most likely going to result from a poor combustion of gasoline (which is an HC in and of itself).

Combustion processes are more efficient (i.e. - gas/fuel is burned more completely, and less unburned gas is passed through exhaust) at higher temperatures. Maybe swap in a warmer tstat just for emissions? I personally have noticed that at low temperatures, and even in the winter, the smell of unburned gas is more prominent.

Also...I agree with the plugs/wires and anything else dealing with the combustion "equation". This is because a poor spark will lead to a poor combustion. poor combustion = unburned gas = high HC count in exhaust

The air filter is indeed the last source to check out. Think of the Fire Triangle. You need air, fuel and ignition source for combustion to take place. If any one of them is lacking, the combustion will be inefficient or non-existent. So a clogged air filter could potentially lead to this, but I would bank it's something a little more serious than this. It certainly can't hurt to check it out though.

And for what it's worth your mileage is very high. With high mileage generally comes some engine gremlins. Good luck trying to track it down.

SVThuh

Methanol... Put a couple of gallons in the tank and run it. Your hydrocarbons will be almost non-existent.

Good luck with it.. And just feel lucky that you dont live in the Socialist Republic of California!

hellostop

My hyrdocarbon failure was due to my charcoal canister dumping raw gas fumes. With your car 10yrs old, put a new on in $40 at autozone. Mounted behind plash pan in drivers rear wheel wheel. This can is vented to intake manifold via a selenoid controlled by pcm. Put 12V to selenoid it should click open and shut - ck to make sure its working ok, blow thru tubing on selenoid as it opens and closes. Theres also a selenoid between gas tank and charcoal can - see shop manual for test - will need hand vacum pump. Shoebox probably has link on his site.
getr'done

David94TA

FastZinTennessee: That is pretty incredible that you passed without a catalytic converter, especially with the cam you have. To what do you attribute your success in passing? They do a visual inspection here in Chattanooga so have to have a cat when doing the test.

FastZinTennessee

No cam at all then! All I had at the time was an intake, SLP headers, Flowmaster catback and an electric waterpump. The EGR, AIR and catalytic converter were removed. My next setup was an LT4 HOTcam, with the same bolt ons, I added a random tech hi-flow converter and it passed with that setup no problem.

I'm pretty sure this new cam is not going to pass I had thought about putting two high flow cats on flanges so I can take them on and off (dual w/ x-pipe), having the tune played with using methanol.

The visual inspection is fairly easy to get around if you are a little resourceful. You can put a heat shield around the area where the converter "should" be

Since the 305 and HOTcam are similar I'd say that you can pass no problem with a hi-flow converter, and with some tweaking of the tune you could probably pass with no converter as long as you added the heat shield mod

FormulaW66

this is nice to hear that u pass. im about to walk outside and start install my SLP headers and Random Tech Cat i just got. i need to pass Cali emissions

while im doing it im replaceing spark plugs, wires, and O2 sensors. lets hope i pass