Catless downpipe and exhaust fumes

[turbo]

I've got a question for all of you who are running catless exhausts on your Sonics....how much exhaust are you smelling? I recently had the ZZP catless downpipe installed on my car along with a straightpipe (2nd cat/resonator removed) back to my factory muffler and tailpipe. The car is loud as hell, and whenever I'm idling in traffic I'm smelling exhaust fumes through my air vents, and also if I open the windows. I didn't realize I would be dealing with these kind of fumes while sitting inside the car. As of yesterday I turned off my catalyst sensors and reset the check engine light. Is this normal? Are those of you with straight open exhausts also smelling these fumes through your air vents? I'm not smelling any strong fumes coming from under the hood with the engine running, so I'm not suspecting a leak, but I'm not sure.

-Thanks

 

[sx sonic]

Sounds like you have a leak. I have to leave my car sitting and idling for a long time before I get much smell.... And my exhaust dumps out after the 2nd cat.

I did have issues with the v-band sealing at the turbo. I had to modify the clamp to get mine to tighten up enough.

Best bet is to go thru all the connections again and make sure everything is tight and sealing.

 

[turbo]

Thanks for the help. How tough is it to get to the V-band clamp? How exactly did you modify it to tighten it enough?

 

[rdss]

I do not smell anything int he car with my BNR down pipe and DDM test pipe either. Like sx sonic said, make sure everything is lined up and tight.

 

[Eric Smit]

my car smells like spiced rum.

 

[rdss]

Stop holding your hand up to your mouth and breathing out! And if your car does smell like spiced rum I'd walk away from it immediately.

 

[$ub$onic]

Hahaha priceless

 

[dvn]

I used to get the fumes occasionally. I recently removed my downpipe and I could see where it was leaking at the V-band clamp.

 

[rdss]

I had to adjust the v-band clamp as well, it had a weird ticking noise that I remeber Eric having back in the day.

 

[turbo]

Does anybody know if a replacement vband clamp is available? How are you guys modifying yours?

 

[rdss]

We are not swapping them, if it's leaking rotate it a little and re-tighten. If you want one (you're probably going to have to go to the catalog tab and enter your car info) they are $17.80 here -> gmpartsdirect.com: Alternate GM Catalog

 

[sx sonic]

The root problem of mine was the thickness of mating flange of the new DP. It was quite a bit thinner than the stock flange. Because of the inherent design of v-band style of clamping this results in the clamp having to be tightened more to draw the DP into the turbo and make a good seal.

This wouldn't be a problem except the clamp bottoms out before its actually drawn in the DP enough for a good seal.

There's also some casting flash at spots on the turbo housing that can interfere with the clamp. This can be overcome by rotating the clamp until it doesn't interfere.

At 1st i rotated the clamp and tighten it more, even thou the clamp was bottomed out further tighting brought the clamp tighter.

It still leaked so I pulled it all apart, cleaned the mating faces, removed the casting flash on the turbo and most effective of all was grind of the tabs on the clamp that were forcing it to bottom out. Where the clamp splits are tabs on each side that will contact if you squeeze the clamp together.... That is what I ground off. (i took a pic I'll post up probably tomorrow that shows it modified.

Thru it all back together and tightened the living sh!t out of the clamp. Leak fixed!

I think the flange on my DP was off more than most thou, so I'd recommend making sure the v-band clamp isn't bottomed out before going thru that hassle.

Oh one more thing I was actually able to wiggle the DP from underneath the car before, it was that loose, it'd be a pretty easy check for you to do.

 

[Kuntryboy865]

catless zzp here and no smell here.

 

[turbo]

Thanks for all the great advice. You guys rock

 

[american_tuner]

Bnr downpipe and zero leak!

 

[turbo]

An update to this thread....I added the ZZP catback, ordered a new factory gasket for the downpipe, and had all this installed at the same shop. I asked the mechanic (a friend) to check again for an exhaust leak. He said everything was fine and he didn't smell anything. I got the car back and it still stank like exhaust fumes. I took it to another guy I know at a local exhaust shop. He found 2 leaks immediately directly under the cab (crappy welds). The welds were done by my friends shop, and not related to any of the ZZP products. He fixed the welds, and suddenly, no more exhaust fumes!