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2009Toyota Matrix Intermittent Rattle

Hello! I’ve been trying to get to the bottom of an intermittent rattle/fluttering sound coming from my car while accelerating. I have taken the car to 3 different mechanic, all who have fixed things but don’t solve the problem. Within the past two months I’ve had the serpentine belt, tires, and sway bar linkss replaced. I’ve had the heat shield and exhaust looked at. The sound does not seem to happen when I first drive in the morning but does occur after sitting in my parking lot at work. It does not happen while I’m pressing the accelerator while in park. It stops after I got 30-40 mph. I’m very frustrated because I can’t get to the bottom of it. Any ideas? Thank you!

Can you post a recording or video of it?

It’s hard to do that because it only happens while driving and I am the only driver in my household. I can hear it best while driving near a wall and will see if I can figure out a way to have my daughter record it later.

it sounds like this noise is just a loose heat shield.

Jack up the car (and use jack stands for your own safety)and shake, tap, and wiggle then to find a loose one.
Or get the car up on ramps!!!
They are pretty simple to replace, just a few simple tools.


Well I had a mechanic check the heat shield 2X and both said it was good, but I have thought this was what it was all along. I have taken drives with the mechanics and they really thought it was tires and sway bar links, but no. This has not been my typical Toyota experience.

Only under acceleration and up to 30-40mph makes me think you might have a pinging engine.

I had a rattle and it seemed to tike me a couple of times to really fine the problem.

I finally had to grab the tailpipe and shake it real hard, and work my way forward.

It ended up being a baffle inside the resonator and until I struck the resonator with a rubber mallet real hard did I find the problem.

So rattles can be hard to locate, when they only appear accelerating at speed.


What would that mean?

Pinging is pre-ignition. The fuel-air mixture igniting before it is supposed to. Can be caused by many things like carbon build up in cylinders, engine running too hot/lean etc. It’s one possibility that could be ruled out pretty quick using the right tools or an experienced ear. When you said they didn’t find anything loose externally, this came to mind. The exhaust rattle Yosemite suggested is another good thing to check. The honeycomb inside the cat breaks down and rattles or a baffle comes loose inside a muffler or resonator…

One thing you could try is to accelerate much more gently and see if the rattle is reduced or eliminated under those conditions. And the opposing condition, if you accelerate harder than normal, is it more pronounced, or the same?

Well there doesn’t seem to be much rhyme or reason to it. Going faster or slower doesn’t seem to affect it. I’m beginning to think. I need to take it to Toyota for assessment.

I just wanted to mention that about 3 weeks ago I was driving this matrix and it died. I was able to get it restarted and drove to one of the mechanics I had taken it to for assessment. They said my head gasket was leaking and it would cost close to $2000 to fix. I drove it to a toyota dealership, they called it a “misfire” when evaluating it for trade-in. By this point I was sick of the car, so I bought a certified used car. This matrix had not been my typical toyota experience. Hoping I have better luck with this one. Thanks for all of your help.

Thanks for the follow-up on your Matrix’s problem OP. I was also thinking the problem was pinging, per TT’s post above. That can definitely sound like rattling, and occurs usually during acceleration or going up steep hills. Pinging can damage the engine’s internal parts over time, maybe that’s what finally happened. Glad you got another car and are back to a reliable ride.