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I've got a 99 Z28, with a Hot Cam, long tubes, Borla, Pulley, LS6 manifold.

I had it dyno tuned, but the shop is now out of business and I think their tune may have been crap. I have removed my AIR system and EGR as well. I'm running O2 sims in the rear and some Denso O2's up front.

The car stinks. Like, burn your eyes out of your head stink. According to the scanmaster, its always adding fuel. I think the last time I drove it the LT trims were positive 5 and positive 7. Pretty sure that's where they were.

When I bought the exhaust, I thought ahead and got a system, FLP, that had interchangeable cats and straight pipes.

So the question is, if I do nothing but put the cats in, and leave everything else alone, will my stink go away? Or, do I need to run the EGR and AIR if I'm going to run cats?

Secondly, could the stink be eliminated by a better tune, and not put the cats in? The car is so lightly modified, that I'm sure a mail in tune would be just as good as a dyno tune. I did all this stuff back when things were kind of in their infancy regarding these cars and engines.

Now I'm at a point in my life, where being loud and fast are only so important. Getting rid of the stink is more important.

Thanks

 

My car used to burn my when I ran it with no cats and a madz28 mail order tune. I put two cats on it a few weaks ago and it was a big help. I can now sit behind the car with it running; befor with the same tune and no cats my eyes would burn at stop lights with the window down. I used catco universal cats.

 

Thanks,

Are you running the cats without the AIR and EGR, or did you still have that stuff hooked up? Ideally, I would like to just drop the cats in, and leave the engine compartment alone.

 

I have my air and egr hooked up. But I don't think you will have a problem; I have a ls1 buddy running a ms4 cam with out the AIR/EGR with cats. It should cut down on the smell a lot, I also think my car sound better with the cats.

 

Well, without cats your exhaust will always have a rich smell (shouldnt burn your eyes though, I know what you mean. My race car did that)
Even when its running lean it will smell rich.. but personally Id at least do a 1pull and steady state dyno session to check your AFRs. If your really running overly rich and you put cats on it will just burn the catalyst up quickly.

Actually I should have read a little further, you have a hotcam. Im not sure of the hotcam specs off hand(ive never used one), but your car may need to be that rich at an idle to idle properly (and accelerate off idle smoothly).
My 550hp stroker would make your clothes smell like they had been wrapped around the tailpipe once you got done driving for awhile. My wife hated when I smelled like raw fuel. (sux to be her)
Air and/or egr won't help anything when your talking about a non-stock cam

J

 

Yes.

My car had that horrible eye watering, asphixiating smell going on at idle because it has no cat. It would probably kill you in minutes if you hung out by the exhaust pipe for too long. So I did an emissions test on it and the hydrocarbons and CO were really high.

I'm not sure how the LS1 is set up, but I retarded the Closed TPS timing (idle timing) from 20 degrees to 5 degrees. This helped the air/fuel mixture burn more completely by delaying the spark until it's compressed more and more volatile. Then my hydrocarbons and CO dropped within range and the fumes were normal again.

Cats definitely do something lol.

 

The missing AIR and EGR aren't making it smell. The AIR only runs at startup to help the cat's heat up. EGR only runs under limited cruise conditions, not at idle or WOT.

+5 and a +7 long terms are not out of line. But they may indicate a problem with a "false" lean condition due to exhaust leaks before the O2 sensors, misfires, or faulty O2 sensors.