HC emissions at upper limit, What to do?

[1kdude]

Hi,
My 99 V6 man trans has 145Kmi, runs very well but the HC limit of 54 ppm is at the limit, CO and NO are fine. car gets 30 mpg on freeway. It has a CAI but otherwise stock engine. I'd like to sell this soon, any suggestions as to why the HC is high? The car does pass smog, is this a problem?

Thanks!
Brad

[fenixus]

try replacing the PCV valve and its grommet. get new ones from dealer, they fit best and do its job right. autozone shit is not worth it, you won't get grommet there (old one is brittle and seals badly) and their el cheapo valves get covered with ugly rust within weeks.

[thaharlequin]

I actually like the cheapo PCV valves because IME the valve and grommet are sold separately, and the grommet is rubber so it shouldn't break up and fall into the cylinder head. Just my 2c of course, YMMV.

dude, is the high HC on the dyno or TSI test?

[1kdude]

Originally Posted by thaharlequin

I actually like the cheapo PCV valves because IME the valve and grommet are sold separately, and the grommet is rubber so it shouldn't break up and fall into the cylinder head. Just my 2c of course, YMMV.

dude, is the high HC on the dyno or TSI test?

This is on the dyno, 15 mph and 25 mph HC #'s both at the 54 ppm limit. since the car does pass California smog, it may not be a problem sales wise?

cheers,

[Jason.MZW20]

Consider changing the O2 sensors if you haven't done so. A vacuum leak can also cause issues as air gets past the MAF and the fuel trims are bumped up. You can also burn off any impurities in the cat by going WOT for a period of time or by using Seafoam.

I have the smog reports of my 1MZ MR2 which is setup just like the M/T 1MZ. It didn't fare well the first 3 times at the BAR. I'm running a CA spec ECU though which isn't proper for this setup.

HCs are unburnt fuel.

Feel free to look at my smog reports:
https://picasaweb.google.com/jasonmzw20/SmogReports1MZ#

For the passing report I resorted to using a one step hotter spark plug. It has a new cat, cleaned/balanced CA spec injectors (10cc larger than M/T injectors, not good for smog either), new AFR sensors/post-cat O2 sensor, etc.

If your CO2 is 14.8-15.2% and O2 is less than 0.2%, the combustion within the engine is efficient.

[thaharlequin]

Has the car ever had the spark plugs changed?