2012 Honda Fit I bought the car from Carmax in August 2024

Shortly thereafter I noticed the sound of a metallic rattle underneath the hood, but in the area that's in front of my feet. But towards the bottom.

And shortly after that I found out I needed a new catalytic converter. So we thought the noise was the catalytic converter and got that replaced, but the noise did not go away.

So it has continued for the last 16 months and over time it has gotten worse. Initially it was just a rattle, and it was intermittent only occasionally.

Then it started being more frequent and more frequent. Then in October of this year, 2025, it started in addition to being a metallic rattle, it is now accompanied by a jerking like uh uh uh. Uh uh uh.

A jerking or a stuttering, but it's not the kind of jerking or stuttering that you feel when you have a misfire. It does not feel like it's coming from the engine, it does not sound like it's coming from the engine. No CE light.

I feel it coming from the area where the metallic rattle is underneath the hood in front of my feet area towards the bottom. You know, underneath against the wall. But kind of right in front of where my feet are or slightly above and slightly to the right. Kind of to the right.

And so now it has this jerking, and it's getting more frequent. The jerking is getting more frequent and the metallic rattle is more frequent.

And I forgot to mention, the metallic rattle and the jerking only happens at acceleration. If I'm on the highway already at speed or even just down the road at regular speed, 35 or 40 or on the highway at 65, it does not happen after acceleration.

It only happens at acceleration. And then once I hit a little higher speed, it's gone. And it doesn't come back unless I then slow down and I accelerate again, and it occurs again. It also occurs more on an incline.

And it also kind of feels like I lose traction with my tires. And like I hop.

It hasn't caused the car to break down or anything. Ive had other problems going on, but this didn't cause a breakdown. I've had, at least four or five different mechanics look at this and nobody ever finds anything.

So I've been working with somebody recently on another issue. And they told me that this was occurring because my electronic shifter was loose and they tightened that up. But that didn't fix it. So then they told me it was my heat shield and they tightened up all my heat shields. But that had no impact whatsoever, it still continues.

So any ideas on what I should tell the mechanic to look for?

I am a 64 year old woman. I do not have expertise in fixing cars. I know quite a bit because I have learned over the years. And I'm smart about it, but I don't know how to fix them.

But I need to be able to guide the mechanics, because apparently they can't figure it out either. So I'm trying to figure out what can I tell them? Where they should be looking.

I had them check the motor mounts thought it might be the motor mounts. But they said it was not that. They said maybe it's my tires but I don't know. Tires can't make the metallic rattle and the rattle and jerking are connected.

I'm worried it's the transmission. I don't know. I can't tell if it feels like it's happening when it's shifting.

Would appreciate thoughts.

Thank you.

 

I have a heat shield rattle that I thought was a noise coming from the engine. I changed to snow/ice tires this winter and the rattle is clearly separate from engine rpm. With my other tires the rattle and engine revving overlapped that it almost sounded like pre ignition. I’m not sure which heat shield it is but definitely one of them on my car. Rattles are tricky. They can even make you think the car is jerking since your senses can play with your mind. Do a little test run over different pavement, a/c on/off clutch in/out etc to try to isolate the sound.

 

To locate a loose heat shield, tap around with a rubber mallet...

 

Checking for rattling heat shields is good advice when you hear a metallic rattle. But, unfortunately, it has nothing to do with "jerking or a stuttering." For jerking and stuttering, I would suggest that you start thinking about fuel delivery systems. I mean that respectfully.

1) Have you adjusted your valves?

2) Have you replaced your engine air filter?

3) Is your battery connected properly, and is it fully functioning?

4) Have you inspected your drive belt? (A bad drive belt may interfere with proper alternator functioning.)

Good luck. Come back here. We will help you.

 

The heat shield was inspected and tightened but that did not resolve the issue.

The drive belt and tensioner just replaced last week, but this rattle and jerking present long time. Not resolved with tensioner and belt.

The rattle and jerk take place directly in front of my feet and slightly to right, not near engine or belt. It dies mot feel like engine jerking. Not like spark plug.

Valves have not been adjusted. Guess it could be this.

Last month spark plug 3 blew out of head and stripped threads. Had a helicoil fix. But this rattle been here 1.5 years and jerking did start right before the plug blew. Perhaps the jerking is not relatd to the rattle.

I wonder if valves damaged from blow out. But mechanic says no.

 

You mentioned needing a new catalytic converter originally. Why?

I'm with Mister Coffee on the fuel system being the culprit. If you needed a new cat because your engine was dumping raw fuel, replacing the cat will not solve the issue.

You said no check engine lights - have you run codes with an OBD-II scanner?

Misfires will also damage the cat. I suspect your engine has been misfiring for awhile (jerking on acceleration) and has eluded detection for whatever reason.

 

I don't think I saw any mention of front suspension and/or driveline (CV joints/axle). This would be in the general location you are describing and could be related to acceleration.

Please keep us updated.

Mark

 

A shot in the dark: try disabling traction control (dash button on your left) then drive through a problem area. A faulty sensor, tone ring, or wiring issue might be triggering traction control, which will cut engine power and/or pulse the brakes (via the ABS unit) to maintain traction.