WRX Cold Engine Whistle

I had a new catless HKS uppipe installed about a year ago. It has the bung for the EGT sensor, and the sensor is still installed. From the start, it was running great and sounding just fine, but over the last 6 months or so, I've noticed this high-pitched whistle on acceleration, usually only when using moderate throttle or more. I'm thinking it is possibly the uppipe gasket leaking. It still sounded fine after taking it to a track day @ Thunderhill in Feb, but it might have gotten knocked around after I took it up to Fortuna and back down the Lost Coast along some rough roads & dirt that, at one point, may have been the cause of warping my 2 front rims (slightly)... Any thoughts?

Category:

Autos & Vehicles

Tags:

• Subaru
• WRX
• wagon
• uppipe
• gasket
• whistle
• exhaust
• leak?

[suprbst]

I haven't completely figured out the cause, but did find that a weld is bad on the flange on the midpipe where it meets the downpipe. I only notice the sound when I'm under relatively hard acceleration when the car is cold. I also notice an exhaust odor when I turn on the fan while the car is cold. Since both the whistling & the odor go away when the car is warmed up, I hope both problems are related to the weld. I'll find out when I take the midpipe off & take it to the shop to have it welded.

[guambombkid]

The smell could could be an o ring problem cause i have the same prob on my 08 and that sound i believe could just be cold turbo idk though

[ibewok]

I have done a lot of research on this problem, and I'm leaning towards the up pipe leak. I understand the up pipe is very sensitive when installing and I have redone the up pipe install twice now and reseated the blow off valve. My sound happened after installing a turboxs up pipe made from cast iron, which didn't fit very wells from the start, for now I'm going back to stock up pipe, its only like 5-10 hp and not worth the headache of a 3rd install.e

[vtrider36]

same sound on my 2004... really pissing me off. if anybody has success with fixing this, please share your findings

[SCdudebro]

@suprbst I have the same symptoms in relation to the noise when cars cold and under load. Only notice the sound when I'm boosting with relatively moderate throttle. I do not notice any exhaust smell though.

Mine recently has begun to make noise even when warmed up now. My recent change was a TurboXS Up pipe. I replaced all gaskets when I did the job and torqued to spec. I'm going to check that my BPV is not leaking an the exhaust manifold gasket isn't leaking first.

[SCdudebro]

Did you ever figure out what the screeching sound was? I'm diagnosing my wrx for the same problem/sound right now. I don't believe it is the uppipe though. I'm leaning more towards exhaust manifold gasket. Any insight?

[BFin26]

def an uppipe leak get a some new gaskets and you'll be fine