So my car developed what I think is the infamous marbles in a can sound at high rpms that sound others have been experiencing today. I tested it out a few times and here are a few observations that might help shed light on the problem:

1. This started today and my car has about 1200 miles on it. The current tank of gas is Chevron 91, which is a bit different from the Shell 91 that I usually run. I haven't been able to put my normal Shell back in to test whether it's the gas, but the sound started about 120 miles into the tank.

2. Oil level is a few ticks below full, but far from the refill line. It's been 200 miles since my last oil change.

3. The marbles in a can sound also sounds like very rapid popping, more like a bunch of sand actually. It starts at around 7000 rpm and increases in the frequency of the popping all the way until 9000 rpm. Though you can hear it above the engine, it definitely isn't incredibly loud. It seems to be coming from the right side near where the glove box meets the center stack.

4. If you hold it at a high rpm, the frequency of the popping also doesn't change.

5. There doesn't seem to be any power (or more accurately, torque) drop from the sound. There is also no CEL. The car pulls just like it always has.

6. The first occurance was when the ambient temperature was in the mid 90s. I took it out at night when it was in the 70s to see if temperature would have any effect. The car is still making the noise even at the lower ambient temperature.

7. I redline at least once or twice per drive, provided the engine is up to temperature, but normally I shift rather low (3500 or below) in an effort to conserve gas.

8. The car developed the sound after I washed and waxed it.

All this information leads me to suspect that it's not detonation, since pinging would've triggered a CEL leading to a loss of power. I also don't think it's a normal part of the SDAIS operation since my car didn't develop this sound until today. Before when I brought it into high rpms it just made the angry vacuum cleaner Wankel sound. It could be a lack of oil in the rotary, but I'm hoping not as that would be bad news indeed.

My gut feeling (wishful thinking?) is that it's unburned fuel igniting in the exhaust manifold. I think that might be the best case scenario too. As to why it suddenly developed it today if that were the reason, I have no real clue. Maybe my plugs have already started going downhill and so isn't firing as well as it was before.

I hope it's nothing serious, but the noise doesn't sound too good. However, there hasn't been any CEL or anything else that is suggesting engine performance is being affected.

 

Interesting- in case you haven't read my thread about this, I'm currently in a dealership saga in fixing this. They pretty much straight up said they can't fix it. So I called MNAO and apparently they're talking to the dealer, though I haven't hear anything for a few days...

Your description is exactly what I experience- but I would definitely say it's loud enough to be noticable. I'm wondering if it has something to do with the cat?

 

well the search function works.....

30mins ago experienced pretty much the same thing, for me it's at around 6000rpm. I haven't sustained that rev range for any period of time and haven't gone beyond as the noise sounds so terminal. Power doesn't seem any worse, just a horrible rattle....marbles in a can

2006 6sp GT
5000miles on the clock
amb temp 87F
oil level at full, topped up just the other day

I've been running 91 octane (premium octane here) since I bought the car in April but the last two tanks have been 87

 

well I've just read a couple of marbles in a blender threads and I'm hoping mine is just down to 2 tanks of 87 octane. One thing I forgot to mention above is that the rattle comes from the left hand side of the engine...

 

voodooray id like to hear your car. maybe if you have time over the weekend we can meet some where so i can get alisten?

 

try some pre mix--couldnt hurt.
olddragger

 

zoom44, not a problem. I'll be messing around with my boat tomorrow at Pier 99/ Jantzen beach...right by the I-5 bridge crossing the Columbia. Failing that, I live in West Linn and could meet you around there. I'll send you a pm with my cell#

 

I've been running my car as usual for the last couple days despite the sound since my gut is telling me that the noise is not all that harmful. There isn't much logical explanation for why I feel it isn't harmful, but I think part of the reason is because I've been testing different parameters to try to see whether the sound would go away. Anyway, here are some more observations.

9. I burned off my tank of Chevron 91 and put in my usual Shell 91. Since then, the sound only happens intermittenly. There are runs where it doesn't happen at all, but sometimes it comes back. Still no loss in power. This might just be a case of bad gas as there is still some Chevron 91 left in my tank from the previous fill.

10. The sound seems more likely to occur when you're taking it into elevated revs at partial throttle. However, that might be due to the fact that the engine is louder at full throttle than partial throtle.

11. When it does happen the sound continues even into my shift as long as the revs are high. In other words, when I get off the throttle to drop the revs to shift to 2nd, the sound continues happening even as the engine revs drop. This is significant as I think the engine cuts the injectors when you're off the throttle so no fuel should be injected into the combustion chamber. Therefore, if it is detonation, what exactly is being detonated? In fact, sometimes I almost think

12. It seems like the problem comes and goes with each different drive. If it does happen, it'll happen for the entire drive no matter how many trips to the redline, but if the sound doesn't come on during the first trip to redline during another drive, it won't come on again until at least after the engine is shut off and started again.

I'm taking the car in next Tuesday to be looked at, but if I can't reproduce it, this might be the first time in the history of the world that a dealer is correct when saying they couldn't reproduce the customer's problem! By the way, what premix should I use olddragger?

Also, I've noticed quite a few 2006s have this problem. Was there a bad batch or something? I have a 2006 6MT base.

 

I have the exact same observations, 2004 MT.

 

sorry voodoo i ddint get around to you today. hopefully soon

 

My 04 use to do that too...
My 06 hasn't got enough miles on it yet....

I eagerly await my marble sound though... not!

 

Dude--- any GOOD full synthetic(NOT CASTOR BASED) 2 stoke motorcycle racing premix. I use Yamaha lube. Lot of good pre mixes are out there. I mixed mine to start with very light--to see how mine would respond. 1/4 oz per gal. After I found favorial results i now mix 1/2 oz per gal or about 8 oz's per full tank. However my personnel blend is blend Lucas Top cylinder lube/injection cleaner 50/50 with the yamaha synthetic premix and add THAT at 1/2 oz per gal. Some people think i am crazy(probably at least 1/2 right!). I also run in the summer (live in GA---HOT!) 10w/30 Royal purple and I sure like my blood pressures better---er I mean my oil pressures. Excessive --maybe--but I sure dont like heat and thin viscosity oils. Engine is smoother and I believe it is sealing better--
olddragger

 

Had a friend help me out today and I noticed something interesting. It seems that if I rev up the engine while the car is stationary, it won't make the noise. Anyone have any idea as to why that is because now I'm just stumped.

 

Well to add my 2 cents to all this. We have been having the same noise or popcorn/rattle or several months now. We now have 7200 miles on it. My computer has been flashed twice and calibrated once. My dealer actually sent it to CA. to be done. Mine at first stated the rattle at 5000 rpm and stop at 5200 rpm. After the first recalibration it was good for about a week. Then it started again. This time it was more frequent and at all different rpm ranges. So of course Tech line said it was the gas. We had been using Chevron 91 oct. So we switched to Shell 91. No difference. Ok yea mine is an 05 Sport with A/T. Then the tranny started to shift funny, Would be in traffic going less than 10 mph and it would shift into fourth gear and not want to down shift unless you floor it. So when we took in back in, they said they couldnt get it to act up, but they did hear the rattle noise. So after calling Tech line yet again, now they are saying it is a normal condition. While at the dealer my wife drove another 05 with 32k miles on it. It also made the noise but was way way less in sound. I think that Mazda doesnt know what it is or how to fix it. I almost sounds like a piston engine that the timing is off. I dont buy the fact that they want to blame the fuel, I personaly think is has to do with some sort of load sensor or infact witht the spark timing. Just in case anyone is wondering I am an ASE mechanic, been doing this for about 9 years. I am no expert on the Rotay, but I know my piston engines, one with 93 k and 192 k dont ping or rattle. I have filed a complaint with MONA and with the amount of time my car has been in the shop in the last 4 months, mine is on the verg of being in the lemon law for WA state. We loved this car till all the problems started. Oh yea we have had to add coolant as well. Dealer said no leak found but my light came on twice and had to add once. If anyone else gets theres fixed please let us all know.

Thanks

 

I don't think the AT's are getting enough oil and that's why they are over heating/ pinging.

What I don't understand is if it's pinging, why isn't the knock sensor working?

Are you sure the marble sound is pinging?

Try the throttle bypass mod to reduce intake temps.

 

That sound annoys the hell out of me. I keep thinking I will hear or think of something to compare it to but I never do. Hope to find the time to get it looked at soon.

 

Has anyone out there gotten this fixed successfully?

 

So my car is at the dealers and the tech rode with me so he definitely heard the sound. He also tends to agree that it's not pinging since there's no CEL or loss of power. I feel it's not the engine and he agrees as the location the sound is emitting from seems to be right behind the dash, an engine sound like that would be muffled and have the edge taken off by the wirewall, but this sound is fairly sharp.

Observation 12 is no longer valid as last night, I heard the sound and then later on in the drive it was gone. The hunt continues, but at least for the moment I get a S40 for a rental car.

 

And it's not the gurgling of the water through the heater core?

There was some mention on the forumn of a motor on the right hand side of the car that makes this noise.

 

I am sure the "Rattle" problem with my 8 is octane related. Just to see what would happen I tried using 87 octane in my second engine and it "rattled" just like the first engine did. The fix for my engine is 92 octane

 

^^I wish that was the case with mine. I have tried all sorts of different gas types, always the highest octane available- all to no avail. I bring it in again tomorrow (third time's the charm!)

 

it seems that there is something (a part or component) that tends to resonate at the same frequency that the engine (under load) is producing during a certain RPM range. It also seems to be dependent on the number of miles of the vehicle, thus thinking to believe it is a BSR issue (Buzz, Squeak, Rattle).
I could be wrong, but probably is not something to worry too much about. But unfortunately it is anoying....

 

It could very well be, but would there still be water through the heater core when the heater isn't running? The first instinct of the tech's was to suspect that it had something to do with the AC, which it might very well be since the condensor is in the area where the sound is emitting from, but it does this regardless of whether the AC is on or off.

 

Well I know the rattle on mine is from the engine compartment for sure. I dont think the octane has anything to do for it either. Has anyone tried using a premix to see if it stops? I know on person was saying they use a premix, but dont remember if it stopped the noise. My concern is what is going to happen as the miles increase. I have under 8k and is makeing this noise. We drove one with 32k and it barely made the noise. I comment of not enough oil being sprayed on the seals might be more on the money, or excess fuel being ignited in the exhaust manifold would make it as well. I know with mine it started only at 5k rpm. After the first flash it started to do it at all different rpm ranges. When mine first started to do it we were getting large amounts of black smoke from the exhaust pipe, hense overfueling problem. Dont get the smoke anymore, but still rattles. As far as the "pinging" noise, that is what it sounds like to me. Then again I have the back ground for this stuff, just not on rotary's. I am sure I will be making another trip to the dealer soon. The tranny seems to be shifting a lot better since we got it back this time. We will see.

 

as fast as my rattle appeared it has now gone, I think it is due to hitting a resonant frequency and it certainly seems temperature related in my case.