I've noticed that my car makes loud "Rattle" noise when I shift from 2nd to 3rd above 5500-6,000 RPM. It happens as I lift off of the throttle before i depress the clutch and shift to 3rd.

I'm not quite sure if it is a loud "rattle" noise or a loud "pshht" (like short burst of air). It sounds like it is coming from the driver's side firewall area of the engine compartment. I don't have an external BOV or anything... could it be the stock BOV?

I rarely shift above the 5,500 RPM range so this is the first time I've noticed it. (I usually shift between 3000-4000 RPM).


Anyone have any ideas? I'm a little worried and I'm not sure if this is normal. If I take it to the dealer and tell them about this will they freak out saying that I'm abusing the car by shifting above 5,500 RPM once every 1000 miles or so? I figure this is a sports sedan so you're entitled to accelarate fast once in a while.

2003 WRX sedan. 19k miles. No mods.

Thanks!

 

Hey Travis, I'm not too sure about this situation but if it's more like a quiet sigh, it's probably the stock BOV (it CAN be heard if you listen for it). Otherwise, without actually hearing, I can't really help you more. Hope things turn out okay.

 

Thanks for the input, Choku.

On the ride home I checked it out again. It is definetely more of a 'rattle' sort of sound. It's definetely not the stock BOV 'sigh' sound. It seems to happen around 6-6.5k RPM. I hardly ever venture into such a high RPM range so perhaps its something normal that I've never noticed/experienced before... but it just doesn't sound right to me.

Does anyone drag their WRX? I'm sure you guys would get into the high-ish RPM range pretty regularly. Any similar sounds? It seems to come from the driver's side firewall area.... if you draw a line from your left hand (on the steering wheel) directly forward into the engine compartment, that is where it sounds like it is coming from.

 

I hit those rpms at least once a week (Im at 45k) and I have never heard the sound your talking about. If it were me I would take it to the dealer and if they say your abusing it tell them you'r driving habits (which are good) and ask them why they advertise 0-60 times on the car and ask them if they think they went over 5,500 rpms to get those times.

 

Okay... I've done a bunch of reading on I-Club and NASOC, and gone for a drive.

I think I might have an idea of what's going on. I think it may be a minor case of compressor surge.

It only happens when I'm going from WOT/Full boost and then quickly lifting off of the throttle. I'm guessing that I'm lifting off the throttle too quickly and it doesnt alow the stock BOV to vent out the boost fast enough.

If I let off the throttle slower, I don't get the noise.

I'm taking in my car tomorrow to get the cruise control re-call clip installed, so I'll discuss this with the tech's while I'm there.

Does this sound correct to anyone who has heard/experienced compressor surge? From what I've read, it normally happens to people with improperly working aftermarket atmospheric BOVs. Has anyone heard of a stock WRX experincing minor compressor surge?