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Discussion Starter #1 (Edited)
Ok, this is weird. I was getting 10lbs of boost when I had an open 3" down pipe about 24" from the turbo. I just ran the cat back setup that goes on the system for emission purposes. Now, you can hardly hear the turbo (use to hear it all the time). I put 2.5" dual exhaust no mufflers and now....no boost. Feels like it wants to go hard, but without the boost it just seems like a naturally aspirated gt. is it possible that the exhaust would really cause this to happen?
That is the only thing I've changed. Just seems crazy, but I'm new to turbos.
Thoughts??
The kit I'm running is the Hellion single turbo kit for a 2006 GT 3v 4.6. Even though I say catback...there are no cats on s this setup. It's all straight pipe.
 

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Something not right there. There's no reason you should lose boost from that. I'd check the turbo. If you're not hearing it, and there's no boost, that points to turbo.
1)See if turbo is spinning, speeding up, etc.
2)Check vacuum lines and such for leaks(maybe vacuum line to gauge is bad)
3)Intake/discharge tube leaks. A bad coupler may look fine until it's under boost.
4)Pull the exhaust back off, see what happens
That'd be my humble route of troubleshooting.
 

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Did you mess with your tuner and set something wrong?
 

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Discussion Starter #5
Yea, all good points. Is there any info on how to make a good boost leak tester on here? I'm going to pull off the intake side today and see if I can finger spin the impeller.
 

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plumbing shops will have them. theyre a plug type fitting with a schrader valve hookup. commonly used to test drain lines during new construction inspections
 

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Discussion Starter #7
Got it fixed. I took the intake side of the turbo pipe off and checked if the impeller was free spinning and it had something making it stick. I turned it forward and back and it started free spinning. So, all that banging and messing with the exhaust could have caused something to stick in the impeller. No oil residue and put it back together. Gets to 11 psi in a hurry now :). I'll monitor it to make sure there are no issues, but seems fine now.
 

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It's something besides an exhaust. My daily has a cat, full exhaust and turbo. I would make a boost leak tester and see if your losing boost somewhere.


Sent from AutoGuide.com App
Any idea how much power you're losing with the cat?
Why did you decide to run a cat? im considering one because of the smell.
 

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Any idea how much power you're losing with the cat?
Why did you decide to run a cat? im considering one because of the smell.
It's actually not on a mustang. It's on a 2000 passat with a ko4. That was just to illustrate that you can still have a cat and 2.25" exhaust and make boost.

With that being said I'm probably losing about 40 hp with the exhaust the way it is.

When I turbo my mustang in the summer I am going to have two different y-pipes. One with cats and one without.


Sent from AutoGuide.com App
 
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