Hi guys,

recently I'm experiencing a rattling noise from 3k to 4k rpm, but only in 6th gear! (manual transmission). It seems to come from between the radio and the front windshield. Maybe where the center bose speaker is located.

This video describes it quite good, but it's a bit of a higher pitch I think (hard to describe to be honest):
It only appears when I accelerate and the heavier I press the pedal the louder it gets. When I let go it completely disappears. Any ideas? Maybe a loose heatshield? (is there one near that location?)

Coils and stuff are pretty new, so I don't think it's an engine related problem. Also theres no power loss or something like that when the rattle occurs.

 

Update on this issue: Rattle also seems to appear in other gears but at different rpm. In 4th gear for example at around 4,5k rpm. Couldn't reproduce it when the engine was still cold, only when it's hot. It also seems to come from underneath the car, but is significantly quieter (maybe the catalytic converter?).

With the windows down you can't hear anything.

Anybody has any idea? The fact that it seems to be on the whole car makes me a bit worried

 

Hi, so I'm pretty sure i can help you out. I had the exact same thing around 3k rpms in lower gears, was afraid it was my transmission cause of the noise was emitting from the center console blah blah blah,
I have a clogged catalytic converter, so in the process of removing it, i noticed my
02 sensor, was severely loose. Right than and there it all clicked, but i didn't dare believe until i turned on my car. Its funny, cause i bought the car with the sound, and the previous owner even told me it was a transmission issue. PFFT
Turned on my car and ever since i tightened that o2 sensor, theres no more rattling noise that drove me crazy.


(the o2 sensor is screwed into the catalytic converter) If you need some help locating it let me know.

 

Hey, I had a similar issue, but the rattling was at around 4k RPM, and it sounded like it was coming from under the passenger seat. If this sounds like the same issue, it could be a bar that is rattling against the underside of the car, towards the passenger seat. I don't know how to explain it, but check if any bars are bent upward more than they should be under your car. That was MY issue, might not be the same for you.

 

Thanks a lot so far I'm getting my catalytic converter changed anyways, so I'll let them check any heat shields or sensors.

The noise is becoming really annoying and I hope this fixes it. The rattle now more or less appears randomly -.-

 

If it is like the video you posted, then it is most likely detonation.

In general, to get more helpful answers please provide the following info when asking a troubleshooting question:

In your specific case, it would also be good to know what octane gasoline you use, if the fuel pump has ever been changed, whether the fuel injectors have ever been cleaned.

 

It's a 2004 with manual transmission and ~43.5k miles on it (first engine).

There are not many modifications which could cause this noise. It has an Invidia exhaust and got a new catalytic converter about 3k-4k miles ago. The old one had a crack in it. At the same time I changed the coils and wires (Bennettbuilt kit) and bought new spark plugs (NGK).

I'm gonna get the cat converter changed on Thursday because I think thats whats causing the noise. The new one is a 300 cell made by KKS Performance. The starter will also be changed because the car always takes some time to start (2-3 seconds maximum cold and hot, the weird thing is that it "wants to start" once or twice during these 2-3 seconds, but doesn't. Sorry I don't know how to describe it but I hope you know what I mean :D Maybe like a hiccup). Watch this video and you maybe get an idea of what I mean, but it doesn't take that long in my rx8 (normal or should I be worried?). Theres no significant difference when starting hot or cold. It sometimes starts immediatly and sometimes does this hiccup thing:


I'm trying to do an own video.

Fuel is 95 octane without premix. (ordered Idemitsu premix oil which should arrive on Monday, maybe theres too much carbon?)

 

Alright got the catalytic converter changed and checked all heat shields. Rattle still not gone

Started using premix but I'm still on the first tankful of petrol so I guess there won't be any change yet.

Any ideas? Faulty ignition? There's no check engine light however.

 

I'm guessing you're in Europe (Germany?) ... Can you get any higher octane gasoline than 95 RON? Try filling with 100 octane and see if the rattle goes away. Sounds like detonation/knock to me, so if it is sensitive to octane rating, then this would confirm it.