Under the hood rattle

So I have a 2007 Mazda 3, Hatchback, Grand Touring. There is some kind of rattle under the hood I can't find for the life of me. I thought it was the intake that goes in to the battery box, but after securing the tube and battery box (which was a little loose due to a broken clip), the rattle is still there!

It only happens at highway speeds, and then mainly when not following another vehicle. It sounds like plastic bumping against itself. The sound is coming from the driver's side, just in front of the dash, as best I can tell. I thought it may have been the shield that sits under the engine, but I tightened that and got a few more clips which were missing, but it is still there!

Anyone have any ideas out there? This is gonna kill the road trip potential for this summer...

Have you tried adjusting the little rubber stoppers on the hood and on your fenders? I had a similar problem where my hood rattled that helped me.

i have the same problem, only when speeding up from low rpm in 4th and 5th. but it drives me nuts, i trimmied plastic away from my CAI, customized my intake because i though it was rattling off itself were it connects together, fastened some things better, moved rubber spacers, added rubber spacers and i'm begining to wonder if it's one of the bad motor mounts thats just allowing to much engine movement. i'll find out if thats the problem next month. i'm ordering heavy duty motor mounts off amazon. i'll repost if i ever figure it out.

More engine movement = less noise and vibration. So by getting stiffer mounts, you're just going to transfer more noise and vibration into the chassis and make more things rattle.

really?? i did not realize that. well anyways. i don't know what the noise is, it never did this before the CAI.

^^ That guy is stupid, I probably have the same rattle, but on the passenger side, and I actually think found my torn into 5 peices, Motor mount xD But if you have more engine movement, your going to have vibrations, ESPECIALLY if you have a broken motor mount....I still have yet to find if its actually the motor mount, but Im pretty sure it is because my Spectre CAI runs perfect with no rough idle.

tiloz95 said:

^^ That guy is stupid, I probably have the same rattle, but on the passenger side, and I actually think found my torn into 5 peices, Motor mount xD But if you have more engine movement, your going to have vibrations, ESPECIALLY if you have a broken motor mount....I still have yet to find if its actually the motor mount, but Im pretty sure it is because my Spectre CAI runs perfect with no rough idle.

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you're pretty stupid for calling me stupid dud! who does that? oh superficial dicks that think they're the s***... and not! just kidding i did realize about the vibration but honestly did not realize of the noise and extra rattling transfer. call me stupid but hey screw you. and sorry i'm not a motorhead genius like you obviously and i did however solve my intake rattle by getting a chip... for some reason that took the rattle away..... SO CALL ME STUPID!! (boom01) because i don't know why the chip took the rattle away. but i'm satisfied anyways! and by chip i mean a performance MAF sensor