Help me diagnose this rattling noise.

[scaryc]

03 WRX - 101k miles

it occurs

1. only between 3k and 4k rpm.
2. only when the car is in gear - and never at a stop
3. only under acceleration, more so under partial throttle


It's most noticeable in 1st gear.

To describe the sound, just tap your fingernails on your computer desk at random and that's pretty close.

The car does not feel like it runs any differently since it began.

I'm really hoping it's something stupid like a heat shield, but I haven't had a chance to check! Thanks guys!

[EvoEatr]

Check that all your exhaust heat shields are securred tightly...

[scaryc]

While checking my heat shields I discovered a nice hard pebble had found its way into my cat shield. Obnoxious little rat! I hope this is the source of the sound. I can't get it out without taking the shields off and now it's raining. I'll have to do it another day. Thanks for the advice!

[EvoEatr]

You could always beat the hell out of the car and hope it flies out....

[DUB]

Diagnosing mystery rattles is difficult enough in real life. Over the internet? Nearly impossible.