Alright well im not sure if this should go in the exhaust section, TPI section or this section but most people browse this forum so ill post here.

My car stinks from the exhaust, thats the smell im talking about. Little info, it runs fine, little rich but not overly rich.

Shorty Headers
2.5" Y pipe
Dynomax Bullet
Edelbrock Muffler

AFPR set at 51psi.

The car smells like gas when it starts up like a normal un-catted car nothing strange there. But once i start driving it starts to stink when i come to stop signs. Not a un-catted car smell like the 60s muscle cars it has a "diesel strong kinda propane smell" I cant really describe what it smells like cause no other car ive been around smells the same.

It seems to really happen when my car backfires, which is all the time. Under de-acceleration it pops a lot and when i shift it backfires. It runs a little rich i know ive messed with the fuel pressure from 45-55psi. The smell stays the same but the backfiring will change as well as performance.

Even when i first got the car, stock manifolds, i gutted the cats, and with a flowmaster catback it smelled the same after driving it for awhile.

My muffler dumps right before the rear axle so you can imagine traffic sucks and it smells.

I want to know why my car smells this way and why it doesnt smell like an un-catted 60s 70s car? I know what a rich mixture smells like and thats not it, im not exactly sure what a lean mixture smells like but i dont think thats it.

So...is it the way the fuel atomizes with TPI or what?

Seriously i like the smell of muscle cars but my car just doesnt smell the same. Im gonna put a cat back on it if i cant figure it out.

Ive smelled new LS1 cars, 5.0 stangs, 4.6 stangs without cats and they all just smell like gas like an un-catted car but my car has a very strong smell that just isant the same.

Oh and theres no paint burning on the exhaust, or anything touching it. Ever since i removed the cats its smelled like that. Ive changed the whole exhaust system twice without a cat still smells the same.

You guys can laugh if you want but try to help! Wish i could let you guys smell it over the internet but im afraid thats not possible.

Thanks.

 

I think you've answered your own question. Adjusting the fuel pressure probably didn't help either. Tuning via injector timing rather than fuel pressure is the proper method. That may solve some of the "backfire" (more probably, afterfire) on decel, too.

Condidering that the LS7 cars will do about 10-second quarters, make almost 200 MPH, and get almost 30 MPG with FOUR catalytic converters, you might want to consider adding some rather than eliminating them. Punchong holes in system components isn't the answer. Tuning the components to work together is a far more elegant and effective solution.

 

Thanks for the response Vader. It was more of a they were bad so ill punch it out cause im a poor kid kinda deal but then when i redid my exhaust headers/y pipe/full exhaust i decided to leave the cats off.

Im aware it doesnt make my car faster, just makes it loud/raspy/polute more.

Its just the actual "stink" of it thats strange and how its not similar to any other un-catted car.

After spending a bunch on my current exhaust system id really hate to spend some more to have a cat welded but thats what i may be doing soon because its just not fun to be around. My exhaust dumps right before the axle so all the fumes are sitting right under me coming up into the cab. I dont like the tone of my current muffler either.

 

If you can install a tailpipe to get the exhaust gasses out the back, it may solve the problems of odor and rumble.

I've done some TPI conversions on older vehicles with no cats. The exhaust odor is just like I recall the older carbed cars when they were tuned and running just right.

 

I dunno if you messed with the distributor or anything, but maybe check your timing. I have gone back and forth i dunno how many times with adjusting fuel pressure and i found that my timing was off slightly and when i would give it gas it would back fire and bog down ect. Also, it gave off a really bad smell from the exhaust becuase it was missing and dumping fuel as well so maybe your problem lies with timing or crossed sires.