Typical Cat Smell or Leak?

[Ebm]

Hey everybody, need to get some opinions. My car has high-flow cats on it. At idle, you can get a good whiff of the exhaust smell with windows down or windows up. If my car is moving at all, I can't smell the exhaust smell. Also, the smell is coming through my vents at idle, but it doesn't come through with recirculate on. Does everyone else's car with high-flows do the same thing? Also, my high-flows may have turned into straight-flows as I'm not sure that the honeycomb matrix inside has anything left.

I'd like to get opinions from guys with high-flow cats and no cats.

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[Jay-rod427]

They're either cheap junk cats, or they blew out. Either way they are not doing their one and only job anymore.

 

[Zelek]

Exhaust leak. I only smell mine in a garage when it's idled for a good minute.

 

[Ebm]

Thanks for the replies. I'll try to take a video of what it sounds like. With the cat smell, it's possible my headers might be leaking. Then again, the cats are rusted on the outside and look like they have been through a lot lol. They aren't rusted through, but just rusted on the outside.

 

[Jay-rod427]

The leak would have to be yuuge to get gas smell, and you'd hear it.

 

[Zelek]

The leak would have to be yuuge to get gas smell, and you'd hear it.

You'd be surprised how well some exhaust leaks are masked. Not all of them make that tinny sound or loud sound.

OP, if you can get your car jacked up, I'd start it up and idle it in the open and do the paper test around the exhaust, but the headers might be difficult to do that. My first guess is it's happening around the headers as that is the most likely spot before anywhere else in the exhaust. Also explains why it's coming through the vents. When the exhaust is flowing, it goes right past the leak with no issue. That's my guess.

Also, did you use stock OEM gaskets or aftermarket ones for your headers? The stock ones are the ones I'd suggest.

 

[Ebm]

The leak would have to be yuuge to get gas smell, and you'd hear it.

Gotcha. Gas mileage hasn't gone down, it has stayed the same. Is it worth changing out the cat knowing it'll probably melt in a few years? I'm on a 93 tune and might be running a little rich.

Also, I know headers have a sound of their own. To me, it sounds like the typical header sound. But I'll take a video because I like to have a second opinion.

You'd be surprised how well some exhaust leaks are masked. Not all of them make that tinny sound or loud sound.

OP, if you can get your car jacked up, I'd start it up and idle it in the open and do the paper test around the exhaust, but the headers might be difficult to do that. My first guess is it's happening around the headers as that is the most likely spot before anywhere else in the exhaust. Also explains why it's coming through the vents. When the exhaust is flowing, it goes right past the leak with no issue. That's my guess.

Also, did you use stock OEM gaskets or aftermarket ones for your headers? The stock ones are the ones I'd suggest.

I've done mods to the car like the exhaust system after the cats, but the headers were done by the previous owner.

I'll try the test out and let you know. Thanks.

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