strange noise
 

i have this weird noise coming from my car when i rev it between 1k-3k RPM's. it sounds like an air leak somewhere but i cant figure out where. it sounds like a whistling noise and you can hear it at idle.

i did a K&N typhoon intake swap prior to this and that noise wasnt present at the time. the only noise i heard was the whistling that the intake makes. i also did an exhaust swap and it didnt make this weird noise.

i drove 1700 miles from vegas to tacoma, wa and didnt have the noise. one day i was heading out and the car had that weird noise. it doesnt sound like the whistling noise of the intake while driving, its that weird noise like it is coming from the engine! i then looked around and noticed that the top of my K&N filter fell off. i used some RTV and put it back on and it fixed it for a day. it came back the next day!
my car will also surge up to 100rpms while at idle with nothing running but the motor. my car idles at like 800rpms and will surge to 900rpms and back down like 3 times a minute. all connections to the intake is secure and doesnt seem to be the problem. i cannot swap my stock intake out cuz it is still at my friends house in vegas (he needs to mail it to me).
i used an engine stethoscope and seems like the noise is coming from the intake tract to the rotary section of the car.
does anyone else have this weird noise?

oh to comment, it is more like a hiss noise from the right side of the car in the engine bay and it does it all the time. it is not a morning thing, its an all day thing!

Yep, I just got a whistle sound yesterday.

trying to track it down.

The idle bounce you describe sounds normal.

Far as the whistling noise, the engine opens valves and does things at various rpms. Have you tried driving down the road in 2nd or 3rd gear and slowly increase rpms all the way up to 7500 and listen carefully? It SHOULD be making some odd high pitched sounds at different rpms.

I don't know anything about a noise at idle, but many people report having rough idles with the K&N filter.

How does one explain the rough idle on the K&N filter?

Yeah those sounds are normal.

I heard the hiss the other day for the first time when I removed the engine cover and drove around. Put the cover back on and I could barely hear it. Good to know it's normal.

Edit: I have the stock air filter box.

yuck i hate that hissing noise, donno why it decided to show up later on down the road instead of when i bought it. with or without the cover, i still hear it.
when i get the rpms up in the band, the noise is barely heard. i can only hear it in the low band from idle to like 2-3k rpm's.
whenever i get my stock intake back, ill give it a swap out and see what happens.

Could the his be intake noise from the air pump? That's on the RHS of the engine compartment

I HAVE THE EXACT SAME THING - I know Im probably reviving an old post here, but im new and just really noticed this the other day. A co worker has an '8 too and he said he had the exact same noise - must be normal.

Hi guys,

I have had this noise for some time and my Service Mgr did find a Mazda Repair Info about it.

Sounds like we will have to live with it.


Mazda Repair Information

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WHINE OR SQUEAL NOISE FROM ENGINE AT IDLE
Applicable Models
Model Starting S/N Ending S/N
2004 RX8 00000000 ZZZZZZZZ

Some customers may complain of a high-pitched whine or squeal noise fromthe
engine at an idle. The noise can be eliminated by raising the engineRPM
slightly above idle. This is most likely caused by the primary port jet air
nozzles and / or the metering oil pump air ports. The jet air nozzles are
located in the primary port of each rotor. The jet air flow is acheived by
using air flow from an area prior to the throttle plate. The metering oil
injection nozzles also use this airflow prior to the throttle plate to
assist oil flow into the engine. This creates a metered
vacuum leak into the engine and may cause a high pitched whine at idle.

This noise is considered to be a
normal characteristic of the RENESIS rotary engine. Use the procedure
outlined in the repair instructions to confirm noise is from the jet air
or metering oil pump nozzles.
1.Confirm noise.
2.Remove engine cover.
3.Locate both air supply hoses for jet air nozzles
and metering oil pump nozzles. Hoses are attached to the air duct located
between the MAF and throttle body. Disregard hose that attaches to the
oil filler tube4.Confirm noise is caused by jet air or metering oil pump
nozzles by temporarily pinching off air supply hoses using pliers.
5.No repairs should be attempted if noise is reduced or
eliminated.

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The rough idle of the K&N is due to the messy airflow delivered to the MAF at low rpms. It is allllllll over the place. If you have an emanage attached you can verify this as well.

Slavearm

Can you live with the rotary whistle??

I thought there would be more comments on this Mazda Repair Information report???