Since the weather's been heating up recently, i've had a chirping sound happen at highway speeds intermittently (every 15 seconds or so? sometimes this doesn't happen). When there's a chirp there's also a sudden lag of power, as if i lifted off the gas in 5th gear. This happened last summer but wasn't really a problem because I lived in Seattle with the weather not really getting too hot.


Any thoughts? 80k miles. Also I've had the P0328 code (knock sensor) but I don't think that's related. Thanks guys

 

Your A/C compressor kicking in?
A/C idler pulley?
Drive belt/s?

 

A/C clutch.

 

AC clutch huh? even though my AC isn't on? Anyway, strangely enough I haven't been experiencing problems lately so if it's not urgent, I'll leave it to for next time.

Replaced the knock sensor, and oh man I should've done that a long time ago. Car runs way smoother now

Also looking to put stock springs back on my car. It came with some crappy lowering springs. Does anyone know if 02-03 WRX stock springs will work for my 2.5rs? Anybody got front and rears for cheap?

 

The pulley is always in contact with the accessory belt, regardless of whether the compressor is being used or not. You could have a wobble in the pulley; damage to the belt itself would not be the cause because the noise would be constant, not intermittent. The drop in power says friction on the belt, because that belt also runs the alternator and is connected to your crankshaft.

 

Do you have the HVAC mode set to defrost or bi-level (windshield/heat)? In those modes the compressor will run automatically without pressing the AC button and the AC light won't come on. The chirp will coincide with the compressor cycling on. You can observe it happening by watching under the hood with the engine idling, you'll see the compressor cycle on and off. It will act exactly the same way as when the AC is selected by pressing the button.
If the chirp is excessive, there are a few possible reasons- the belt could be improperly tensioned or worn, the AC idler may be shot (very common), the system may be overcharged, or the clutch itself could be worn.

 

Hm, thanks Mulder. Do you suggest that I just replace the AC Idler and see if that solves my problem?

 

Check it first. With the belt off, spin the idler by hand. It should turn smoothly and quietly with little or no free play. If it's rough, noisy, stiff, or very loose, it should be replaced.
Also check the belt condition and replace it if it has a lot of cracks or appears glazed.

 

sounds like it could be the ac clutch