Any tips to decrease HC for emission

[wesam]

Any tips to decrease HC for emission for camed cars ?
It seems that leaning the car in the idle area will not decrease HC

Thanks in advance

[5FDP]

Maybe running a higher RPM in park will reduce it. It should burn more fuel and do it cleaner.

[wesam]

Do you mean that HC will be decreased if the mixture is richer ?

[MikeOD]

More spark advance helps, but it will also increase the NOx emissions.

EOIT helps too.

[edcmat-l1]

More spark advance helps, but it will also increase the NOx emissions.

EOIT helps too.

NOx shouldn't increase at idle. Not enough load.

HCs increase as you move away from stoich, either direction. You can have elevated HCs both rich and lean.

EOIT should help, but as long as you have overlap, you'll have elevated HCs.

[MikeOD]

True, but if he's failing for HC at idle, and lives in a state with a drive cycle, he's probably got too much HC everywhere. NOx emissions will increase with more advance off idle, I've seen it happen on many cars...usually from people going past MBT on an engine that doesn't wind up knocking due to the light load.

Another option is bump up the cooling fan on/off temps to allow the engine to run hotter during the test...and get the cats hot before you go test, take it for along drive.