nmilosev

Dear all,

I hope you can help. I have had my RX-8 for two years now, a very nice example. It is a 04 MT 231HP Nordic Green one with just 45000kms on it. I love the car!

Recently it developed a weird noise. It isn't noticable at a standstill but very noticeable under load. Car runs and drives normally no CEL. It sounds to me like an air leak of some sorts, it is related to engine speed not the wheel speed. I've taken it to service but they are not sure what it is.

I managed to catch it on a video so here it is. You can hear it especially when the engine is under load. Sounds almost like a blow off valve.


Any help would be greatly appreciated.

Thanks!

mazdaverx7

iTrader: (6)

First off, Nordic Green is by far my favorite color on the 8. When they were new I went to the dealer to buy one and I was told i could have red, black, silver or grey. The dealer told me that Winning Blue 8's would be coming and that Nordic Green and Lightning Yellow would have to be located and none were available in the network. Bummer. I bought a black one but I do have an 04 Nordic Green 6spd GT in my collection now.

On to your question. The noise initially sounded like interference through the radio but it's not terribly clear to me. You'd get this in older cars when using the incorrect spark plugs. Your noise seems slightly different. I would try removing the drive belts and starting the engine and revving it to different rpm levels and see if the noise persists. My first thoughts are a failing bearing in one of the accessory drives or a belt that has been tensioned too tight. But you didnt mention any recent service being performed on the car so I'm not sure.

nmilosev

Dear mazdaverx7,

Thank you for your reply, first of all!

My video isn't the best really, it's recorded on my phone so the audio isn't quite there.

This "issue" I have is really interesting. I think that you are right in suspecting that it is related to audio. Here is why. I found these two videos (of the same car): and
Here it is much easier to hear the whistle noise. It is the exact same noise I have! What is bizarre is that my car has the same level of equipment as this (down to the leather color!). So it leads me to believe that there is something really specific about Bose sound system or sat nav system.

I also talked to Josh, the legendary rotary mechanic and RX-8 specialist from Rotary Revs UK and his first hunch was that it is indeed the audio system. Specifically he mentioned that there is a wheel speed sensor in the center console near to the audio lines.

Here is some more information:

1. My car developed this noise about a month ago. However I once heard it before, a year ago after a long (10h+) drive in the summer heat.
2. My regular service (oil, oil and air filter) was performed on May 15th (1000km ago) at Mazda Service Center in my hometown. I use 5W30 Mazda Ultra Oil specifically designed for our cars (I think irrelevant here).
3. Spark plugs were changed last year also at Mazda Service Center. I doubt they would install the wrong spark plugs and I checked the receipt. NGK L and T plugs, all normal. (but good suggestion)

Suspecting that it is an electrical issue I tried disconnecting the battery and reconnecting it half an hour later. It didn't seem to help.

I ruled out air leak, because: Josh told me I would have power loss or CEL on, and I checked my vacuum with an OBD2 port and it was normal (around 16inHg at idle no load).

So, to summarize:

a) it is probably normal, just a combination of audio/sat-nav systems making the noise
b) air leak unlikely
c) belts or pulleys, could be, needs checking

Let me know what you think!

Cheers

nmilosev

Dear mazdaverx7,

First of all thank you for your reply. Nordic Green is indeed awesome!

Your suggestions are very welcome! I think I found something very interesting regarding this issue.

Now my video really isn't the best, especially the audio part. However I found these two (of the same car) that are much better:

and
Here you can hear the noise, and it is the exact same noise that I have! Now this is bizarre because this car has the same level of equipment as my car (satnav, bose etc.). To be even weirder I found another car with same equipment that has the same noise! Here it is, you can hear it: Again exact same trim level down to the leather color! I am not sure about American trim levels, does GT means you have satnav? In Europe, my package is called Revolution Top (funny for a rotary engine ).

I think your suggestion about audio interference is very probable. I also talked to Josh, the legendary rotary mechanic and RX-8 specialist at Rotary Revs in the UK. He also thought it could be electrical/audio, specifically he mentioned that the wheel speed sensor could be interfering somehow with the audio system. To that's my first suspect for the noise. I tried disconnecting and reconnecting the battery but it didn't help. It's worth noting that with the car standing still it's almost impossible (or even impossible) to hear the whistling noise. The only noise is the engine noise and the mechanical noise.

Belts, as you said, are another option that I didn't look into in great detail but also had considered to be at fault.

I think I ruled out the air leak, Josh told me I would have power loss and CEL on. I also checked the vacuum and I have 15inHg on idle, with engine warm, AC off.

Also sorry for not including additional details: My last regular service (air filter, oil filter, oil) was on May 15th. Spark plugs were changed last year, water pump also, and I had my coolant flushed with Mazda FL22. All this was done in Mazda Service Center and I really doubt that they used wrong spark plugs - I also checked the receipt, NGK L and T's, all normal. The oil is 5W30 Mazda Ultra Oil for RX-8's specifically.

The car developed this weird noise about a month ago, although the first time I heard it was last year after a long (10h+) drive in the summer. It was gone after the car cooled down and reappeared exactly one year later.

The car is running great, I have all the power I ever had, no overheating issues, anything. Oil is fresh, I only use 98+ octane fuel (Europe octane ratings) and in general car flies. It's just the whistle noise. For now I just have to live with it and I hope it somehow gets resolved. Either goes away or I figure out what it is.

Let me know what you think and if you have any other ideas! Thank you again!