Last night, as I was decelerating between 30-50mph, with the clutch to the floor, I noticed a rattling noise coming from the center or right side of the car. It went away when applying the brakes. Sounded like a rock in a can being shaken around. Everything about the car seems normal (turbo, cornering, shifting, etc.). I could just be paranoid and it's some ice or snow caught in my brakes, or maybe something got kicked up in between the plastic skid plate and engine, so I'll be checking those out tomorrow when I have a chance. In case it's not one of those cuplrits, does anyone have suggestions of what else to check? I tend to be somewhat anal in regards to her (and I just re-read that, and had to laugh a little :hsugh. Thanks! 2007 WRX, 54k mi, practically stock in mechanical terms except for an open source tune from Nate and exhaust removed from the cat. back.
Kinda hard to e-diagnose sounds but could be anything from detonation to afterfire to a loose heatshield to road debris like you said. See if you can replicate the sound and datalog if you can.
Doesn't sound like back-fire at all, even small backfire. Heatshield, forgot about that one. Datalog as in hook up a reader to the car's computer? Don't have one of those, but Tim might. Working all day today, so it's gonna have to wait until tomorrow. For now, I'll take it easy on her.
I have had this problem for years. Same thing. No issues with the car's operation, just a rattle during decel. Mostly in the lower gears. For me, it's the J - bracket that bolts the exhaust to the transmission. The bolt could have backed out, or rusted out. Not sure how to fix it because I never bothered to. But the sound you hear is likely exhaust vibration rattling the j-bracket against your transmission.
