I've had some trouble with my Colt. Whenever i accelerate i hear a metallic voice, suggesting a heat shield. - I took it to an authorized Mitsubishi dealer and sure enough, there was a loose heat shield right under the manifold. They made a new metal piece and welded it on and put back on the heat shield.
The problem is, that yes the heat shield got fixed, but the sound is still there and it really annoys me. A few months back my manifold heat shield was also loose due to one of the bolts and arms having rusted. They created a similar metal piece and had it weld on and then put the manifold heat shield back on. - and bum no voice back then.
However 1-2 months after they fixed the manifold heat shield, the new metallic voice came. It is easy to hear if the car is being started, while it being cold outside and also if under heavy acceleration (most at 1800-2300 rpm). The Mishubishi dealer had it back in and checked the remaining heat shields but said all of them sitting perfectly without any loose ones. - he then send me home and told me, they would need more time to determine what the problem then was.
However at $100 an hour, I would really like to find the problem first and then get them to fix it without having to diagnose it and spending hours on that.
One last thing, the noise is coming from the passenger side (right) and the noise is less when the car is warm.
I hope that anyone has heard something similar and had it solved
Sound to the rattling noise - best at 1:30-1:39: