Rich Fumes

[heavyfoot]

Are any of you experiencing rich fumes. When I start my M6 car in the garage and allow it to warm the exhaust fumes are so rich my eyes burn. If I allow the car to warm with the garage door closed, when I go back into the house you can smell the exhaust in my clothes. I have eliminated the CATS. I have SLP long tube headers and Corsa Pro exhaust. I'm running closed loop with MAF. Once warm when I watch the FJO wideband it looks like I'm right on AFR. These rich fumes never go away. My exhaust tips are so black I can't get them clean. I have stock injectors and the IFR table has never been modified. MAF is completely stock (screen and non-polished). I thought moving from 22* spark to 28* spark for idle would help but it doesn't seem to have affected it. Any ideas?:bawl:

[98SS2836]

Ya thats why they put cats on cars say hello to LT's and no cats. You Have super high Emissions at cold start. I bet you can hear if it's still there the air pump turn on and off.

[heavyfoot]

I thought you'd say that. By the way forgot to mention that Air Pump is removed. Would reinstalling help situation. Also the issue is beyond startup. Drive the car for 4 hrs, stop at a light with T-tops off and you begin crying.

[VetPet]

Did you ever have this issue before removing the cats? I'm willing to bet not. Put on a set of hi-flo cats as they flow so well it doesn't make sense not to run without any and your smell issue will dissappear. Cats were designed for use with unleaded fuel and when you remove them you get that 'rich' smell. My old musclecar used to do the same thing when I put unleaded fuel in it but as soon as I put in some good leaded racing fuel the smell would dissappear. Thought about installing cats as the car was a convertible but wound up selling it to get my C5 convertible.

:cheers:

[Bruce Melton]

You will never lose the smell but it will be much better if you can get the LTFTs ~0 at idle. That may be difficult with a cam.
Of course worse when warming up > rich.

[heavyfoot]

Never had the issue before removing the cats. $$ is the issue. Guess I'll have to save up. Is the issue the lack of cats or the fact the O2 sensors are so far away and as the burn fuel moves down the exhaust it "leans" out, hense the O2's are lying to the PCM. At the combustion port the mix is 14.63 but a bit farther away at the O2's the mix is 15.0. As a result the PCM believes it's lean and adds fuel to compensate for the "distance"???

[Bruce Melton]

I believe it is just no cats. If you have no exhaust leaks and the 02s are working, the distance back from the engine is not a big issue.
Untill you get the idle tuned, don't give up. Mine has been lots worse than it is now. (no cats)

[98SS2836]

I have a constant 14.6-7 idle AFR It still doesn't matter Its going to smell with no cats

[98 tigershark]

hello,
I am 98 tigershark, I am now building my motor, Like LG MOTORSPORTS> They recomend no rear cats/o2 sensers, However The EFI Tuning tutorial say you need all four o2 sensers. I am going to try something and I will let you Know if my eyes burn

[heavyfoot]

ok, thx

[VetPet]

LG Motorsports Pro Long Tube headers cause problems with the rear 02 sensors because they wind up being a lot farther back in the exhaust system. Rear 02 simulators were available that would trick the computer into thinking that everything was o.k. but I believe they're no longer available. The other way is to edit out the rear 02 sensors. I guess they can eliminate the cats in Texas because they don't have emissions testing and to extract that last bit of power. If you're not going to run cats and have access to a leaded fuel (aviation fuel) then the smell won't be so bad but won't be good for the front 02 sensors. You might want to try posting on the Corvette forum in the parts for sale section to see if anyone has some cats and an x pipe you could use with your headers. Hi-flo cats cause very little in power loss.

Good Luck! :cheers: