Failed Emissions

I just got back from my emissions and I failed due to too high of HC at idle. It was 373.6 and the limit is 220. I would like to know whats causing this and how I can cure my emissions problem.

 

[Yiuwa]

Mods?

 

None, bone stock. 167k

 

[jogalant]

Hope this helps...

Hydrocarbons:

Measured in PPM (parts per million), this is the result of unburned fuel making it out the tailpipe. This failure is usually caused by an ignition (misfire), or an engine problem such as a bad valve. An engine running too lean will often have excessive HC due to what is called a "lean misfire". Any leaks in the intake system or bad injectors will also cause excessive HC due to uneven fuel distribution.

Failed the HC!

Check the ignition system first. This usually caused by an ignition miss. Then check the engine. Poorly seated valves, leaking head gaskets, or other compression problems will put the HC readings through the roof. Also check for vacuum leaks and the injector spray patterns. Remember, HC failures are usually caused by compression or ignition problems. Improper fuel distribution/vacuum leaks will cause misfires that will cause excessive HC.

 

yeah thanks, that was helpful.

 

The car has good compression so how should I go about checking the ignition system for a misfire, how can I find out which cylinder its at?

 

[teet]

if you have a true misfire you'll feel it.

more likely you're getting "incomplete" burn due to a weak ignition or the computer is adding too much fuel due to a worn out Oxygen sensor.

replace:
plugs
wires
Oxygen sensor

You'll pass no sweat.

john

 

Upsteam or downstream O2 sensor?

 

I also failed in WA because of high HC at idle. Turns out my cat. was bad. I replaced it and passed easily.

 

[teet]

Quote:
Upsteam or downstream O2 sensor?



there is only one on 91-92 galant vr4s

 

[Yiuwa]

If you have a logger you can tell your O2 reading right away, or else try to get a voltmeter to measure it on respective PIN in ECU

If your O2 sensor is normal it should be cycling between 0 and 0.9X volt in idle, and ~0.8x volt during WOT. A dying/dead sensor will output very low voltage, which tells the ECU to inject more fuel then necessary and made you failed the test

 

Change your oil before you go in too, that'll drop the HC's a bit.

 

RETARD YOUR TIMING. Nothing hurts HC's like too much ignition timing. Less timing = higher EGTs = the fuel not burned in the combustion chamber burning in the exhaust system.

Also, while waiting in line, keep your RPMs up to keep the EGTs up, which will make your cat work better.

 

[Romanova]

I leaned the sh*t out of my car while I was waiting inline... I also used some 87 octane gas and some isopropolwhateveralcohol...

Helped pass my car... no cat, no emissions stuff, blah blah blah. Try a search and you will see that you are not the first person, nor will you be the last person to fail emissions. /ubbthreads/images/graemlins/smile.gif

 

Leaning it out too much can cause a lean misfire which can make it fail worse. Make sure you don't do that /ubbthreads/images/graemlins/smile.gif

 

Consider testing on lowest octane gas you can safely run. Octane inhibits knock by suppressing combustion, which will tend to raise unburned HC levels.
Mike R.

 

[Mark LaVallee]

With a fresh O2 sensor, mine passed handily.

Make sure it isn't burning oil, also.
And make sure the cat is HOT!!!!!
I drove mine 75 miles to another Emissions station even though I am a CT Emissions Inspector!

 

Retard your timing by a couple o degrees, toss some "Heat"(alcohol) into the tank & get that cat hot as hell by running up the freeway. If you have to wait in line at all keep the engine rpms up at about 2k while you wait so the cat won't cool off & you should pass given that you are very close. after you get tabs I would look into why though, if tuned properly your car should sail through.

 

[Jostar]

Quote:
I also failed in WA because of high HC at idle. Turns out my cat. was bad. I replaced it and passed easily.



I passed emissions without a cat, i lean it out on the afc, and check my fuel trims,
i passed with flying colors, the tech was holy sh*t your car pass like it was brand
new, but then again people that fail emissions have other engine problems.

 

Well I bet it didnt help that my plugs were gapped to .040.
New plugs, wires, and o2 sensor are in and the miss has gone away.
Ill be headed to the emissions place on saturday to try this again, hopefully with better results.