I have noticed a sound come from my 2004 RX-8 about 55K now that is VERY noticeable when I accelerate heavily in first in second gear. The noise is like like a heavy pinging on metal.. almost like something banging around inside the engine like BB's hitting a tin can. I first thought it was knocking but I started using 93 Octane and the problem remains. Any idea what this might be or some self diagnostics I could try to narrow down the issue?

Thanks in advance.

 

Four suggestions:
1. Tell us more about your car such as service history, mods, any other recent issues, etc.
2. Advise what octane you were using before switching to 93 and for how long.
3. Make a recording of the sound and post it so we can hear what you are hearing.
4. In the meantime try a little search on "marbles in a can" or MIAC - (jumping ahead a little on this point).

 

+1 on the suggestions

Another possibility is that part of your cat has broken into pieces and is rattling around.

 

1.) No mods. No real problems outside of what everyone else experienced with the 2004 when it first came out. Recently the battery went dead and the tires and brakes were replaced.

2.) Was using 87-89 Octane depending on the station.

3.) Can't imagine what type of equipment I would have that could separate out the engine noise from the actual sound. It's more like I feel it in the steering wheel concurrently with hearing it that makes it describable.

4.) Will search after this post.

 

Running octane under 93 is a potential problem. When you search on MIAC you'll find posts with sound clips in them. Maybe can use those to decide if what your hearing in those clips is the same as with your 8.

 

Better description of sound.

I had a few people ride with me and the best description of the sound is like a marble dropping into the center of an aluminum pot. After having a lot of time to hear the sound it is almost always a single klunk like into an aluminum pot.

Any more ideas on what this could be?

Just to reiterate, this is a 2004 RX-8 with about 55K on it. I have always used 87-89 octane and NEVER had a pinging problem so I find it unlikely that its the octane. Other threads even argue that using the lowest possible octane produces the best HP in the 8 along with other vehicles.

 

i dont know what your rx8 owners manual says but mine says premium gas only. If there was damage done because of using 87 putting 93 in now wouldn't change a thing.

 

I know of a few owners that were tuned exclusively for 87 and had no issues. But I

Sounds like engine knock if it is the "coffee can" noise. My take is serious engine damage has taken place and the engine is toast probably.

Best bet is to take it in and get a compression test done, this will tell you the health of the engine and whats going on.

The only other thing I can think of is your ignition system needs to be replaced check your coils and plugs and look at wear and tear on them.

 

OP, are you experiencing any power loss or lag? Car driving any differently than before? Car act different before and after the noise? You mention noise when "accelerating in second gear". Out of curiosity, does it happen at any other time?

 

I don't notice any performance issues at all. The cars seems as peppy as usual and sounds great except for that occasional plunking sound which only lasts a few seconds during each trip if it happens at all.

 

Have you done a de-carbon cleaning?

 

No but I will look into it. I will be taking it into the dealer shortly.. I am now getting a bit concerned and don't want any damage to my engine.. Will reply back if they find something conclusive .

Thanks again all.

 

Some cars had issues with the SSV valve flipping between open and closed causing a banging noise.
Easy to check... Just wire it in place and go for a drive.

 

I can't tell from your first post..... Is it just the most noticeable when you are accelerating hard through 1st and 2nd, or do you only hear the sound when you are in 1st and 2nd?

Cause a bunch of the stuff that it sounds like it could be wouldn't only be happening in those gears.

 

Just wanted to update everyone on what the mechanic did and says the problem is.
Went for a test drive with one of the mechanics VERY familiar with the RX8. Fortunately the sound occurred twice during the test drive and he clearly said it is pinging. Not what I am used to hearing and the mechanic says pinging in a rotary engine sounds quite different than the typical IC car. He also does a firmware update (apparently I was behind) and pulls a TSB that shows clearly that Mazda acknowledges the pinging sound and that it absolutely will NOT damage the engine.
So hopefully that's it for now... but what perplexes me is why did it just start now after 55K???

Any more comments and or thoughts are welcome...
TIA

 

Could be carbon build up that is preigniting...try Seafoam($8 Walmart).