I was thinking that 87 octane might be good because it would be easier for it to combust all of it. But I also hear that if I use 93 octane that the ethanol (I'm not sure the exact name of it) will mask some of the fumes. I'm currently not passing Hydro Carbons, it has a standard of 2.00 and I've got a best (out of 3) of 3.56, and this was before I did any general maintenance. (EDIT) Also, I failed the NOx and it has a standard of 3.70, and my best (out of 3) was 5.27 (after driving the card hard, about 90 for 16 miles). The worst was before any general maintenance, which was 7.82


So my question is basically. Should I use low octane because it will combust easier, or higher octane because it will mask the fumes better?

Also, I used that STP Fuel cleaner or whatever it is (red bottle lol), is there anything that I should use that would help mask this also? (please, brand name, full name, and how much I should use on half a tank of gas)

You guys are great about replying to my questions, and I applaud you, you have more patience with me than I do

 

lower = better combusting yes. Since HC = misfire, you're better off doing the lower octane IMO. You can add ethanol to the lower octane gas anyhow.

What have you done since the first failure? Since it's a misfire, and you're not WAY out of range, you're basically guaranteed to pass if you do cap, rotor, wires, plugs, and make sure the cat is functional. I've passed L69s with a hollow cat, but it's not easy.

 

I've already done plugs, wires, cap, rotor, along with oil change, oil filter, air filter.

 

Check to make sure your egr is functioning properly.

 

So I took it into a shop that my step uncle recommended (he's a mechanic as well, but only works on Volvos). They were brutally honest, and said that the EGR looked fine and that the 5.0L engines from these camaros dont typically have problems with the EGR. And he showed me from my DEQ Test results where I was failing at, and what that meant. So he told me that the Cat's on our cars were made to only last about 8 - 10 years, so it's long over-due for a new one.

So I'm out getting a new catalytic converter put on at Meineke. 99.95 for the cat, plus whatever they happen to charge me for labor. I'mma go broke lmao.

 

You may very well pass with a new cat (which I've said in another of your threads). You very well could have multiple issues contributing to the failures (which has been hinted by all of the responses to your other threads).

This particular mechanic is erring in two ways: 1) EGR's definately do have problems on these engines (for instance, I described my blocked EGR passages in another of your threads) - a search on the board will indicate what all can go wrong; 2) In general, a catalyst, by defination, is not consumed by the catalyzing process. The only things that can make a catalytic converter not "last" are issues secondary to the process - improper tune that over-richens the mixture, leading to excessive heat that melts the supporting material; poor maintenance such as neglected oil changes that cause excessive oil consumption and coat the catalyst material; moisture from short trips leading to corrosion that errodes the supporting material; damage such as hitting speed bumps; etc. When I gotten new cats, there has been an information card in the box stating they don't normally wear out. There was another card that was to be filled out by the person replacing the cat explaining to the "controlling legal authorities" why they were replacing the cat. The purpose was to help lower fraud from shops saying you need to replace this expensive item because they "only last 8-10 years", or something to that effect. How effective that is - probably not very, because most consumers never see the box the replacement cat comes in.

You've asked several questions on several threads on several forums about your problem. The thread titles don't always point to the primary problem. This approach has not kept all the pertinent information in one place, nor led people to look at the issue from a broad perspective. You might want to stick with the thread that is best stating the problem and converging on the solution.

BTW, have you ever checked the timing?

(FWIW, one of the cats, that isn't supposed to wear out, that I replaced was on my '84 full size Chevy van. After 130k miles and 18 years, there was absolutely nothing left inside the case. Another was a '92 Lumina with 140k miles - the cat bed was a solid mass bouncing around inside the case.)

 

yup, a blocked egr passage could be it, took my intake off and it was blocked more than I could imagine, anyhow I hope you get it figured out.