My car, which I just bought is putting off some heavy exhaust fumes, but it isn't putting out any failure codes to the computer. It runs good too, but the fumes are not really something I enjoy to smell. There is no CAT on the car, and I think it is a flowmaster muffler, all 3" and 2.5" pipe.
FYI: the fumes don't stink, or anything, they just have that old car gas smell to them. And I don't see any smoke.

Any ideas?
Thanks

 

What induction?

 

its probably because you have no cat? This is what happened when i gutted mine. And it wont throw a code unless ur on a highway doing the same speed for about 10-15 minutes, then the ECM will go into diagnostic mode and throw the code.

 

It's not the lack of a cat.... cars didn't do this for all the decades before they invented cats, and they don't do it now just because the cat isn't there. Removing the cat doesn't cause codes; the computer has no way of knowing whether it's there or not.

Heavy fuel smelling exhaust is caused by {drum roll please} too much fuel going into the motor. It boils down to figuring out why the mixture is too rich, which of course varies depending on whether it's carb or FI, and which FI system it is.

 

Im running hedman longtubes with true duals to 2 chamber flowmasters and I have a smell sort of. If you stand behind it for to long your eyes will start to water. No black smoke so I am not running to rich I don't think.

Without a cat the exhaust will definetly smell "different" than with a cat correct? If you say no then Im assuming the cat doesn't do much.

I understand that the catalytic converter is a catalyst that speeds up a chemical reastion. Not sure what chemicals get changed to what tho.

 

It does smell different, certainly; but it shouldn't make your eyes water. That's from running too rich.

 

I am running TPI induction... Any idea what would allow too much gas into the engine. I thought the computer would throw a code if it was running too rich...

 

Not necessarily. The only way the ECM would know that it's rich is by way of the oxygen sensor. If that's bad, specifically if it always tells the ECM that the exhaust is lean, then the ECM will be constantly working its butt off trying to richen it up.

Try a new O2 sensor.

 

i have a hollowed cat and my exhaust stinks, i am running a little rich, i can see this on my lap top. but the job of the cat is to heat up and burn the unburnt gases in the exhaust, if theres no cat, its not burning the unburnt gases, theres ur smell.

 

my exhaust smells so good I turn the car on inside my garage with the doors closed. Helps me go to sleep easier too.
haha, actually I wasn't aware that our car's exhaust fumes would be an issue unless you could smell them inside the car, but I could see how leaning the mixture would help some.

SLP-Irocz - I dont think a catalytic converter is as simple as you think. The "precious metals" inside the converter "convert" the otherwise pollutant gasses into other, safer gasses by seperating and bonding the elements diferently. This is why steam and water comes out of your exhaust. example-
HC and NOX go in, H20 comes out.

 

Perhaps this will help:

 

Ill sell you a complete dual exhaust kit for 250$ + shipping.

Hedman longtubes
S extention
equalizer pipe
2.5 inch pipe
2 2 chamber flows.

ready to bolt on BTW