Emissions

[mike]

I took my emissions today and I figured that I wouldn't pass, but just wanted to see by how bad. The carbon monoxide limit is 30 and I got 18, the hydrocarbon limit is 2.00 and I got 3.46. They said if I just got cats that I would pass. I was surprised on how good it failed. Hopefully with cats it will pass.

 

[gofstbuick]

What's the O2 content? B/c a cat needs oxygen to function properly. If the O2 out of the exhaust is already zero, then a cat won't do it. If your O2 content is anywhere above 0.3 of a percent, then it may help. Here's the deal. You have a three way cat installed on your buick. There are two beds in the cat. The primary bed is for NOx reduction. The catalyst material is rhodium. The absense of O2 puts out the combustion process in this bed and reduces NOx. As the O2 senses low O2 content, it tries to richen the mixture. It usually over compensates enough to make the mixture rich enough to use all the O2 in the combustion process. This is the instant when the cat is trying to reduce NOx. Now the other side, the second bed of the cat is for oxidation. This side requires O2 to help complete the combustion process (in the cat). Chemically speaking, if you add O2 to HC and CO, plus heat, you get CO2 and H2O (carbon dioxide and water). The cat uses platinum or paladium as a catalyst that is coated on a screen type material. Also coated with the platinum or paladium is a chemical called cerium. Cerium attracts O2 and stores it in the screen (substrate material) until it can react with HC and CO to convert it into CO2 and H2O. So when the O2 sensor senses a rich mixture, it will compensate by leaning the mixture. It usually overcompensates a little. During lean mixtures, there is excess O2, and this is where the cat gets O2 for the secondary bed or oxidation bed. The engine and oxidation process creates heat, enough heat to continue combustion in the cat. Misfires, leaded fuel and coolant kills cats. If your car misfires excessively, it puts too much O2 in the cat and it starts to over oxidize and begins to glow bright red.
I was just thinking, if you don't have a cat on your car, ignore my ramblings .