So about two days ago i was driving down this rough dirt road to a friends house, (they are everywhere where i live and impossible to avoid), and on the way back into town i was trying to drift around some of the corners, once i got back into town, i noticed that after the RPM's dropped down to idle, lets say at a red light, then when i gave it gas this rattling sound, like rocks in a can, would appear for just a split second and not come back until the RPM's dropped again, also today i noticed that if i brake with some force, pedal down about half way then i would hear a similar noise, like rocks rolling. I have an 04 6speed MT GT, and i really have no clue whats going on, it just sounds like some rocks got stuck somewhere but i don't know where and i don't know how to get rid of them, any help please?

 

No ideas anyone??

 

Are you sure you didn't get rocks stuck in the chassis somewhere ... the words "rough dirt road" and "drift around some of the corners" are dead giveaways that there may be something stuck up in your chassis.

 

First thing you should do is isolate where the sound is coming from. Have someone stand outside and walk beside the car while you drive around.

 

Ok thank you ill get back to you tomorrow.. also im gonna try an undercarriage flush at the local car wash see if that helps at all. again thanks for your help

 

I just think its odd that they move when i revv my engine a bit from idle.. that part doesn't make much sense to me

 

Just in case you havent worked it out, what grabbed my attention was the braking hard then accelerating. I had a similar problem which occured after i had 3 coils die and i still drive it to the mechanics.

Check the catalytic converter. when you brake the broken fragments are sliding forward in the exhuast and then being pushed back when you accelerate.

 

Oh ok great ill check that but i think i diagnosed the problem, im pretty sure i got some rocks in my exhaust pipes and their stuck there, i havent had time to take it off and clean but when i do i double check the cat too, thanks!

 

I have this exact same problem. It started after my coils went bad and the miss fire caused gas to get to the cat. Got the coils and plugs replaced and the car runs fine but the sound of rocks in the exhaust happens under braking.... then if I press the throttle in neutral it happens again as if my exhaust is pushing them back the other way. I think it is the cat but I have to take it to mazda for them to take a look.

 

im having the same EXACT issue. its so annoying and sounds terrible! i had to replace my coils and had a CEL also so theres another similarity. let me know what you guys find so i can fix it to plz n thank you.

 

any update on this?

 

Yeah, i Guess there were rocks in the exhaust, i took it apart and cleaned it and the problem was gone =)

 

hmm..thats so random haha what part of the exhaust? the cat? or did u just take off the entire exhaust? thats guna be a *itch....have to lift the car..ugh

 

Haha well, i took off the entire exhaust which was probably too much, all the rocks were pretty much in the big muffler...

 

hmm..i have stock exhaust though. do you think our situations are the same? its SUPER annoying and its pretty loud. totally kills the sexy sound from the engine/intake haha

 

Yeah i have stock exhaust too, mine wasnt THAT loud though, enough to notice