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Discussion Starter #1
Hi all. Read this site from time to time but never really had an issue to post but now I need some help/advice. I have a 2013 Roush Stage 1 Track Pak with only mods being K&N carbon fiber CAI, Roush axle backs and SCT Bama tuned mostly ran in race mode. Car has always sounded perfect but a few weeks ago noticed it had a sudden exhaust leak sound on cold start up that lasts about 15-30 seconds and goes away. When in 1st and 2nd gear can run to redline and sounds fine but if you are loping in 3rd gear or higher at low rpm and gas it up it sounds perfectly fine 'til you hit exactly 3000 RPM then has a distinct "flutter" sound up to about 4500 RPM and goes away. Sounds identical to an exhaust leak. Have had it to the local muffler shop and to local Ford dealer and both say there is no leaks in the exhaust. Took the muffler shop owner for a ride and he instantly heard it but has no idea what it is since he is convinced it has no leaks. Sounds like a leaf caught in a running fan. Have put 200-300 miles on it and does not seem to get any worse or change in sound or RPM range...any ideas? Thanks
 

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Discussion Starter #4
Thanks for the replies...I only hear the flutter in the 3-4500 RPM range moving in 3rd gear and up. It sounds the same in that RPM range if your in 3rd at 50mph or 5th at 70 mph. Revving up sitting or in 1st or 2nd gear cant hear it. Revving and holding at 3500 can't hear it. Sounds like it is on the drivers side somewhere between motor and drivers seat. Also can't hear it in any gear if only 1/2 throttle or even 3/4 throttle but hear it everytime at WOT. Not sure if above 4500 it goes away or exhaust sound overpowers it and can't hear it. I would think the heat shield would be more of a rattle/buzzing type sound but will check.
 

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I would loosen muffler clamps wiggle mufflers then re-tighten. It must be loud if you hear it at that speed rpm.....are the tips hitting rear valance?

low rpm = 3500-4000 makes me smile
 

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Discussion Starter #6
That is along the lines I was thinking. I ask the muffler shop guy about just loosening or even taking entire exhaust off, inspecting and reinstalling with new gaskets but he did not think he would find anything. Said he listened with a stethoscope and would have heard it. Also said he did not see any markings on the exhaust that indicate a leak? I'm still thinking it is a pin hole, muffler gasket or header gasket. Could something have broke loose inside a collector or muffler?
 

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I've been having the exact same problem with my 2011 GT. It's been going on for about 2 months and no clue what could be causing it.
 

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Discussion Starter #8
Took to another Ford dealer yesterday outta town, know the owner pretty well. Him and tech took it out and drove it. Both def heard it. Put up on the rack and ran it but can't hear it. He called me last evening and said everything on top end checked out and no signs of engine issue. Inspected exhaust and everything looks good. They are puzzled just like the local Ford dealer and local muffler shop. They are going to take exhaust apart today and see if something broke inside collector or muffler. Will update when I hear something.
 

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Took to another Ford dealer yesterday outta town, know the owner pretty well. Him and tech took it out and drove it. Both def heard it. Put up on the rack and ran it but can't hear it. He called me last evening and said everything on top end checked out and no signs of engine issue. Inspected exhaust and everything looks good. They are puzzled just like the local Ford dealer and local muffler shop. They are going to take exhaust apart today and see if something broke inside collector or muffler. Will update when I hear something.
Any update? I forgot to add in my original reply that I have Roush axle backs and a Bama race tune as well.
 

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Discussion Starter #10 (Edited)
Picked it up last evening. They could not locate it. The "flutter" sound did change a bit..."flappier" sounding and lasts a little longer up in the RPM range. The tech said there was an area of adjustment that changes the exhaust/interior noise level that he adjusted....have no idea what he is talking about there, maybe someone on here does....that may be what changed the sound. Starting to think it is something loose that starts hitting at that RPM under load but they said they looked and tightened everything they could think of. Tech said if he could get it to do it sitting still he could find it but pretty hard to look for at 50-60MPH LOL It's not a speed thing though it's a load/RPM thing cause sounds perfect at any speed unless WOT at 2500-4000 RPM
 

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I think mine has something to do with the shifter. If I put slight pressure on it, the rattle stops. Does make sense since it started a couple weeks after I put on the blowfish shifter bracket.

Sent from my SM-G935P using Mustang Evolution mobile app
 

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side question, if the axle back connection with mid pipe is not completely secure will it be enough to cause a noise or effect performance?
 

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side question, if the axle back connection with mid pipe is not completely secure will it be enough to cause a noise or effect performance?
If the AB isn't secure to the OA pipe, it can certainly cause noise, but it won't effect performance.

Also, @Mfields, this thread is from 2016. Why not start a new thread.
 
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