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Exhaust smell and Jerkiness with cobb stg2


05GTLTD

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Those of you running completely catless and cobb stage 2. Have you guys noticed an increased exhasut smell in the car will at idle or a stop light. Also, seems to be apparent when driving with a window open or in stop and go traffic. For now I'm dealing with it, but may have a high flow cat put in to help with the smell. The other thing that I've noticed more so now then while running stock or stg 1 is the tendency for the car to be a little jerky when letting off the gas and getting back on it, especially while crusing on the freeway. I'm leaning towards running rich (stock blow off valve) sometimes b/c the problem isn't always there. I'm thinking of getting some stiffer engine and tranny mounts to help with this, b/c when it happens it feels like my stg4 wrx did with the stock mounts, very lose. On the wrx the mounts helped, but having it retunned help more. Whats everyone esles feedback on these issues?

 

EDIT-WRX was catless and I never experienced the exhausted smell to the level that I am in the Legacy, also I checked all the gaskets, no leaks.

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Does your boost flutter under full boost? if so revist your uppipe and down pipe gaskets (tighten them up if they are a bit loose)...

 

Smells like a exhaust leak..

 

Boost is stable, car basically hesistates then goes, regardlesss of flooring it or not. Up pipe has been on the car sense the day I picked it up, the exhasut smeel didn't surface until the installation of the perrin down pipe which eliminated the last 2 cats. I was thinkking it might be the half-a** setup of flipping the donut gasket when installing the downpipe. Another reason for thinking its that gasket is b/c it's directly underneath me as well. Then again it could be the upper DP gasket under the hood, though both don't seem to be leaking when I inspect them.

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My guess is an up pipe exhaust leak. When you installed the DP, you tweaked the up pipe out of position.. The downpipe flange at the turbo is usually a pretty solid connection, and I can't see the gasket on the other end of the DP causing this.. Unless things are radically different from the WRX, I'd wager a dollar or two on it.

 

jb

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My guess is an up pipe exhaust leak. When you installed the DP, you tweaked the up pipe out of position.. The downpipe flange at the turbo is usually a pretty solid connection, and I can't see the gasket on the other end of the DP causing this.. Unless things are radically different from the WRX, I'd wager a dollar or two on it.

 

jb

The other end of the DP mates with the existing Y-pipe, but they have you pull the donut gasket off the stock pipe, flip it end for end and put it inbetween the new DP and the stock Y-pipe, I was very skeptical of this and don't think it makes a very good seal. The other that bothers me is that the smell comes and goes. For now I'll live with it b/c I like how the car feels. I'm merely curious to see if others are experiencing similar problems.

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Time to spray some soapy water on the connections and watch for bubbles. Have to do it cold and lay underneath while someone else starts it but it will show leaks that you can't feel or hear at idle. Only way I found my uppipe leak.
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Guest *Jedimaster*
Sounds like you're breathing your own pollution.

 

Not a bad thing in my book.

I must be getting old because I agree with you- I feel a bit irresponsible getting rid of all the cats. I think one is enough, but none just makes me feel...bad or something.

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05GTLTD, I have the same setup as you and I also have been noticing a lot of exhaust smell. It's to the point that I rarely drive with my windows down or moonroof open anymore! I don't notice it when everything is closed up.

 

I don't hear any of the tell-tale signs of an exhaust leak, so I'm hoping that's not the case.

 

And I agree with you on the connection between the downpipe and cat-back. That didn't seem like a good seal to me either. I am considering having a custom cat-back built with a high flow cat right behind the downpipe to see if that helps...

 

Doug

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05GTLTD, I have the same setup as you and I also have been noticing a lot of exhaust smell. It's to the point that I rarely drive with my windows down or moonroof open anymore! I don't notice it when everything is closed up.

 

I don't hear any of the tell-tale signs of an exhaust leak, so I'm hoping that's not the case.

 

And I agree with you on the connection between the downpipe and cat-back. That didn't seem like a good seal to me either. I am considering having a custom cat-back built with a high flow cat right behind the downpipe to see if that helps...

 

Doug

 

I'd be curious to know the results if you do this.

 

How about others running the high flow cat version of down pipes??

 

This is another option, sell the catless and buy a high flow cat version.

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If anything you are probably leaking exhaust from the connection between your DP and your stock catback. That is where I am leaking..though small. Regardless of whether you have a leak at the DP or the UP, you are probably going to continue to smell that exhaust depending on which way the wind decides to blow. I only seem to smell it when I stop in my drive way. I am considering going to a hi-flow cat, and sell my catless DP. It depends on what my next upgrade will be.
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