Fellas I have a rattling sound everytime when I take my foot off the gas and the engine winds down. When I'm idling I rev the engine and take my foot off the gas and as the rpm decreases there's a slight rattling sound. It also happens when I'm in gear also, for example if I'm down shifting to slow the car down, I downshift then take my foot of the gas and as the car slows down and as the rpm's decrease theres a rattling sound. The car has a 60 or 2500 mile warranty so I need to find out what it is as soon as possible..

 

my vote is the cat converter. I'm having the same problem.

 

ditto. it's either the cat itself, or the heat shield around it has come loose.

 

Alright I'm gonna check it out today. Thanks guys

 

its either your cat or the wastegate

 

I'm having the same problem. This heat shield really sucks.

 

Yeah guys I actually listened to the car when it was idling and theres a rattling sound when it's idling too, slightly like a diesel engine would sound.

 

Yeah, if your heat shield isn't the problem you'll need to get a new converter welded on. You can let it be, but I wouldn't advise that. It is possible that pieces of the honeycomb MIGHT get into the combustion chamber and thats bad. I've been running with it for about 2,000 miles. That having been said I'm fixing it next week.

How many miles on your car?

 

You need to listen real close to the cat and turbo. If you think the heat shield on the cat is rattling, press on the heat shield with a board or stick to stop the rattling. If the rattling doesn't stop, it's your wastegate and I bet you have a rattling wastegate flapper. They usually rattle due to the set nuts on the actuator arm loosening.
The bad news is that the turbo has to come out to reset them and tighten them.

 

Tha car has 78,000 miles on it, engine was replaced at 65,000 miles..

The car still has th lemon warranty (60 days or 2500 miles), Now I have to get the dealer to accept the fact that there is a problem..