Just "finished" putting in my petit downpipe today. All in all the install went well. I even thermotec wrapped it. However, I started it up and I hear either the exhaust pulses or a leak. I'm a pessimist so I think it's a leak, but I can only hear it at certain times. I really have to listen for it. Shouldn't it get much louder when I rev the car up or under boost?

How noticeable are the exhaust pulses for you guys that have dps?

Thanks in advance,
-ray

 

I have the same thing, some times if I listen it sounds like I have a leak. I decided that it is probably just the exhaust pulse noise making it through the dp.

 

Did you use new gaskets and torques them down properly?

 

I think that is normal, I have that too, and I have seen post on this.

 

I think that is normal, I have that too, and I have seen posts on this.

 

Excuse my ignorance, but what are exhaust pulses?

 

I reused the turbo to dp gasket. It looked like it was in good shape. All the other gaskets were new ones.

I thought I torqued it down properly. I'll be retorquing it tomorrow to see if that makes any difference. I'd be doing that anyway I guess.

I'll post how it goes.

 

I haven't had a chance to retorque the bolts yet, but have driven the car around a bit more. I still can't decide what I'm hearing. I've even driven around in parking garages and parked next to walls. I haven't smelled any fumes yet either.

Any suggestions for definite tests? I was thinking at startup maybe I could see some of the typical smoke that you see on a cold day coming from the dp to turbo joint if it was leaking.

I've had exhaust leaks on other non-turbo cars and know what that sounds like, but I can't really decide about this noise I'm hearing.

On a side note, the improvement the dp makes in spool up is really sweet.

-ray

 

When I get on it and pass somthing like a Jersy Barrier, or a sound baffle wall on the highway, I hear a noise that I think is an exhaust leak. It seems to be coming from just aft of the passenger door and is a stuttered sound. For some reason it makes me think of the sound an ABS system might make when pulsating. This is the only way I can describe the sound.

 

That's pretty much what I'm hearing too. I still haven't had a chance to retorque the bolts as Michigan weather sucks, but I did start it and look for the typical cold weather condensation. I didn't see anything in the engine bay or under the car.

Makes me think it's not leaking as the noise also doesn't increase with the revs, but I'm still not sure.

Thanks for the input.

-ray

 

If it's a leak, you should see some heat and smoke.

Maybe the DP is too thin? What DP you all use?

I don't hear it on mine (PFS MS DP)

 

Mine is the petit SS one.

 

I don't think it is a leak because it has been with the car as long as I have owned it and the exhaust has had a thorough inspection.

 

Also a Pettit. But I get the impression the sound is behind the downpipe. Would be nice if I could tape a couple of microphones in place and listen.

 

Are you guys talking about "droning"?

 

Describe what you mean by droning. I don't think that's what I'm talking about in this case, but maybe.

What I'm hearing sounds more like the individual exhaust pusles inside the downpipe. It also sounds like a mild exhaust leak.

 

Droning

See the above link for what seems to be a good explanation of the sound.

 

Ok. I just retorqued the bolts and started the car up while it was on the jackstands. I still here the sound, but I checked all of the dp connections with my hand and there is no exhaust coming out. Then I stuck my ear on the dp (it was cold and is thermal wrapped) and heard the noise very clearly that way. So, I'm pretty sure the noise I'm hearing is just the pulses inside the pipe being transmitted through the pipe. Weird. And I did check the O2 sensor to make sure it was tight too.

-ray

 

Definitly not droning. Droning is a constant sound that can vary in pitch and is not really related to hard excelleration, but constant speed. What we (I think I can speak for the others) is a stacatto sound.

 

Think I've got the same thing... Only happens at idle though. I'll have a constant idle sound/pitch, but every 5 to 10 seconds or so it'll be like it misses a beat, not quite a popping, but almost.