The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Just failed emission test, now what do I do?

**kwmech** · 07-23-2005, 09:39 PM

Close --- CO is fuel delivery or raw gas, and HC is the engines ability to burn the fuel (or CO) HC is partially burnt fuel. So if you have high CO the engine is working hard to burn it, thus high HCs. Then again if you lean out an engine you can have a lean misfire and have high HCs also.

07-23-2005, 09:39 PM	#8
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,718	Close --- CO is fuel delivery or raw gas, and HC is the engines ability to burn the fuel (or CO) HC is partially burnt fuel. So if you have high CO the engine is working hard to burn it, thus high HCs. Then again if you lean out an engine you can have a lean misfire and have high HCs also.