Change is sounds after ......

I'll try and keep this short if I can, 2000 Jetta ALH straight piped, nozzles, stage 3 malone ,stock turbo. I kept getting the CEL for over/under boost putting it into a limp mode so I decided I'd start with doing the oven cleaner in the turbo gig and I figured if I'm doing that if may as well remove the egr, add the "race pipe" and the cooler delete at the same time. I removed all unneeded vac lines and replaced the one to the turbo. Everything went as planned no breaks or **** ups and I haven't had the CEL come back on (yet) but the whole sound of the car has changed! Before I could barely hear the turbo whistle but the blow off noise was loud now I can really hear the turbo whistle and the blow off noise is nearly gone unless I'm really on the throttle. Also the exhaust is even louder than before , for a straight pipe car it was fairly quiet before but now you can really tell. Anybody know what the hell would make it do all this?

How is it running?

Maybe you're now getting all the boost you should? Perhaps you previously had some under boosting that wasn't quite enough to trigger an error message? Those are my first thoughts

It seems to run fine other than it doesn't seem to have the top end pull it used to, I haven't had to to hook up the VCDS and check the boost levels but I'm not getting the CEL anymore. I might try one more round of cleaner in a day or two. I wouldn't imagine that the egr delete would do anything to up the exhaust noise since it was disconnected (but not blocked) when I got the car. The exhaust noise seems like it has doubled

Before you would be hard pressed to tell the car was straight piped but now it's pretty obvious

Mine is straight piped and is still relatively quiet and manageable.

The turbo does a good job of cutting the noise down. The block off plate for the EGR delete is important to keep the exhaust gases in the exhaust system. It is also a good place to mount an EGT probe.

Are your vanes moving freely? There is a noticable difference in exhaust sound on a straight piped car at idle and driving, between when the vames are operating right, and when they're stuck.

I had a vacuum pump on it while the cleaner was working and it didn't seem to move very much , I had my vnt-17 on the bench just to see the difference and the 17 moved alot more. Could all the extra exhaust noise just be the turbo stuck open a little bit?

What's the blow off sound?

The release of air pressure from the turbo, I know it doesn't have a "blow off valve" like a waste gate turbo but I'm sure you get the idea

That's the point. There's no "blow off valve" so I don't know what you were hearing.

PB_NB said:

Mine is straight piped and is still relatively quiet and manageable.
The turbo does a good job of cutting the noise down. The block off plate for the EGR delete is important to keep the exhaust gases in the exhaust system. It is also a good place to mount an EGT probe.

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While the block off plate is an easy place to mount the probe it does not result in accurate EGR readings.
I tried that first but was amazed by the higher temps and faster response after mounting it closer to the turbo inlet.

I think you have a boost leak.

IndigoBlueWagon said:

I think you have a boost leak.

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I like this guess, something is leaking

Pssh.

KLXD said:

That's the point. There's no "blow off valve" so I don't know what you were hearing.

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Well I'm not hearing anything now if that's makes you feel better. Any clue as to why the exhaust noise is alot louder than it was before I started all this or are you just here to pick apart my wording?

Ok people since there seems to be to much worry about my wording of the blow off sound let's just drop it and move on please.
Does anyone have any idea as to why the exhaust is alot louder now than it was when I started all this? Before the car sounded great a little whistle and not loud at all now it sounds like a car with no muffler on it and not in a good way

I know exactly what you mean by blow off sound. I can almost gaurentee you the vanes are stuck. Not sure what size exhaust you have, but the stock exhaust straight piped has a very prominent blow off sound. My 3" system did away with most of it.

Boost from the turbo reduces exhaust noise. If the turbo isn't boosting properly the car can be louder. That in combination with the lower power delivery you mention makes me think there's a boost leak somewhere.

If you have VCDS you could run a boost log. But I'd check all the intercooler piping and the turbo inlet. It's possible you bumped something or it wasn't fully reconnected after the work you did.

It's also possible that you're not getting enough vacuum to the turbo to close the vanes and make full boost. You might want to re-check the lines to and from the N75 to make sure they're connected and in good condition.

ghohouston said:

I know exactly what you mean by blow off sound. I can almost gaurentee you the vanes are stuck. Not sure what size exhaust you have, but the stock exhaust straight piped has a very prominent blow off sound. My 3" system did away with most of it.

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This would do what you're experiencing, too. Maybe the oven-cleaner made the vanes sticky and they won't close. See if the lever that goes to the turbo vanes moves freely.

What IBW said...

Sounds like something is going on with the vanes allowing the exhaust gases to pass by making the exhaust louder.

When I start mine up, it has a bark for a second and then quiets down as the turbo gets spinning. My setup is similar to yours. Maybe that is a clue to the noise you are hearing now.

ghohouston said:

I know exactly what you mean by blow off sound. I can almost gaurentee you the vanes are stuck. Not sure what size exhaust you have, but the stock exhaust straight piped has a very prominent blow off sound. My 3" system did away with most of it.

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Thank you, thats pretty much what I thought was causing the code and limp mode and after running the cleaner in the turbo I can move the actuator fairly easily now and no code has popped up since (knock on wood). I'm pretty sure it's stock size exhaust ,I've only had the car for a month. Should I be worried at all about all the extra exhaust noise? Not any of the turbo noise just all the extra tailpipe grumble

IndigoBlueWagon said:

Boost from the turbo reduces exhaust noise. If the turbo isn't boosting properly the car can be louder. That in combination with the lower power delivery you mention makes me think there's a boost leak somewhere.

If you have VCDS you could run a boost log. But I'd check all the intercooler piping and the turbo inlet. It's possible you bumped something or it wasn't fully reconnected after the work you did.

It's also possible that you're not getting enough vacuum to the turbo to close the vanes and make full boost. You might want to re-check the lines to and from the N75 to make sure they're connected and in good condition.

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Thank you for the info, I'm going to recheck everything an I'll run a boost log for sure(I should have done one before too)