Rattle Noise at 2k RPM - help!

Hi all,

I bought a 2010 Mazda 5 a couple months ago with 108K km on the clock.

Had to get the sway bar bushings replaced and the passenger side engine mount. These helped solve some knocking and vibration issues. However, there remains a really irritating sound that occurs in the 1900-2300 RPM zone when pressing the gas. Engine sounds great otherwise, at lower and higher revs. Idling in neutral, the engine is practically silent. I cannot replicate the sound in neutral regardless of revs.

The sound appears to come from under the central part of the dash but hard to say exactly. It is a light clickety, rattling sound. Imagine shaking grit in a small glass jar. I have taken two mechanics for a ride and they hear it but say they don't know what it is - annoyingly it is always quiet when I show somebody else! Nothing major they say, like the engine. It is costing me money to be told they don't kkow what it is. It's getting on my nerves and I want it solved.

I assume such a sound, at a given rev range, is related to vibration of a loose part, like a screw maybe, or two materials connecting and resonating. I've tried exploring under the hood to find loose components. I braced the hood prop and radiator with tissue as these seem a little loose, but the noise still happened. I've been holding all different things in the cabin to see if I can isolate it. No luck. I did wonder if there is something in the trench beneath the wind screen, connecting under dash to under the hood (by removing the windscreen cowl)...

Any ideas? I've searched extensively online. Some people mention similar but the threads never seem to reach a conclusion. The car is otherwise fine but I hate it at this point and want it sold - except I'd sooner fix this than try to stiff somebody.
 
I had a similar issue, that I had posted on this forum. The sound you describe is exactly what I was hearing that seems like it is coming from the the front dash, but at a different RPM.


Just over a month ago, I got the car for it routine 80,000km service, which uusually is an oil change, full inspection, and brake service. I also, advised the tech of noise. They called me back advising that they have no records of the car getting a throttle body service and they also saw quite a bit of carbon build up, and in regards to the noise, they will need more time and investigation to look into the noise as it was not fairly obvious. Based on what they told me what the extra inspection/investigation was going to cost, I passed on it. I did however opt for the throttle body service. Suprisingly enough after this service, the rattling has disappeared. I have done everything I could to get it to come back and cannot.

So when this car was purchased at 63000, it should have received a full inspection, and did a routine maintenance at 72000. The rattle was not resolved at anytime during these inspections. I am thinking it might have been the throttle body, service but cannot confirm for sure. hope this helps.

Also, the heat shield (which is what I suspected), was fine and was not loose from the the dealer had described.
 
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