Hello,
My car was hit in January on the driver's door. Dented the door...had to replace it and fender bender that had to be fixed. They said the engine was fine....but a little bit after that we were hearing the engine or something under the hood/or car making a click/rattling noise when we would accelerate.
Now it only happens if we are in 1st...take the rpms to about 2-3, then go to 2nd...take the rpms to 4-5 then the car makes a rattling noise until we go into 3rd. This will happen a lot if we are going up hill. We took it in 2x and they didn't find the problem. They hooked it up to the diagnostic machine and didn't find the issue. but when I took it home and the next day I heard the same noise they couldn't hear. So we took my car in AGAIN...but this time drove a mechanic with us to hear it. And he heard it. They've had the car for over 24hrs now and are still trying to "hear" it again and find the problem. Any idea why...what...is causing this problem. Its a new car! only has 17K miles on it! I could understand if we were going way up to 6,7,8 rpms...but we aren't. It makes the loud rattle when we go to 4,5,6. Oh and the other day the engine malfunction light came on while it was happening...it blinked then came off. Someone Help me. Thanks!

 

The only experience I have with a loud rattling noise is my cat/heat sheilds
CAT was shot and rattled crazy loud on certain rpm's
BUT since its a new car, I DOUBT its that...
thats my 1/2 cent lol
Goodluck