9kredline

When I go to redline the car and the RPM'd climb after 7k, I hear a loud metallic raspy noise comming from the front passenger side from the bottom of the car. Its almost like a loud vibration that gets rasppier and rasppier as the rpms climb to redline. Does anyone have any clue what that is.

I notice this sound on cold days and it doesnt always do it. I called mazda and the service manager told me its some kind of body shield? Either way should I be hearing this or no? Mazda says its normal. I doubt it though

dannobre

iTrader: (3)

Heat sheild on the manifold or CAT?

Shouldn't do this....get them to figure it out and fix it....

mysql101

hard to say from the description. Due to the rpm range being described and no such sound when it's cold, it might even be detonation. Does it sound like beer cans being crushed?

9kredline

This happens when its cold and once in a while, but it sounds kinda like metallic rocks hitting the bottom of the car under the passenger floor mat. i have no idea what it is

9kredline

and yea i guess you can say it sounds like beer cans crushing

9kredline

Actually yea not that i think about it, thats exactly what it sounds like...like a bunch of beer cans being smushed and it gets louder and louder but when i shift and am lower RPM the car sounds awsome.

mysql101

Take the car in for servicing and don't go over 5500 rpm till then. You could be causing serious damage to the engine and may need a replacement engine...

9kredline

I doubt that, the car only has 1000 miles on it. Either way its under warrenty so if i did need an engine then they would have to cover it, but in that case i would get rid of the car.

John Corbitt

I had this happen to me at full throttle in third gear above 8000rpm. I think it was detonation. I only use premium. It happened once, on a cold day. I think my computer kept the timing too far advanced. I did a coupple more runs, and it has not occured again.

John

9kredline

Now when you say detonation, is that a bad thing? Are Rotary's known to have this happen once in a while? Is this kind of the same thing as backfire in a vette or stang? This only happens sometimes. I just drove the car and it was PERFECT....I seriously love driving this car!!!!!

mysql101

What you describe, if it's detonation should never happen. If it's happening, you could be damaging the apex seals and the car will eventually lose compression and run like crap (if at all) since it will not be able to seal properly. If it's detonation, even if your car checks out okay now, you could find the seals break up sometime down the road from the damage it's sustained now.

Of course, we don't know what's actually happening since we're going by what you're describing... and there's been several members on the forum who've had it happen without ill effects. That said, you do not want to ever hear it, and it would be stupid to continue without getting it fixed.

9kredline

I can say this...I am going to have to take it to Mazda, but how can i prove that it does it? Also if you are right and this is a problem then a rotary engine is a piece of **** and i can safely say that if your logic is correct. I hope its not but you never know then right.

mysql101

what kind of gas are you using? what brand, what octane?

9kredline

im kinda worried about this. Can detonation be caused by bad plugs? I did take the car in for the emissions recall and it seemd fine before and after, but I never redlined it before the recall was done.

9kredline

I only fill up with 93, Shell. I wonder if they messed somthing up during the reflash and the change of plugs??? What causes detonation, and why is it only sometimes?

Winfree

Might be a loose plug or something not set right - pester dealer or check with another one if possible - every patient needs a second opinion

05TiGr8Lady

Checkout this thread and others like it... you could have the infamous "marbles or sand in a blender" situation:

https://www.rx8club.com/showthread.p...hlight=marbles

Happens to me too at high RPM's. Sometimes it's louder than others. No power loss or other problems detected so far and I just hit 12K miles.

Razz1

Sounds like the ports opening up to me. It's normal. But really hard to tell by the way you describe it.

9kredline

I just took the car to the dealer and they told me that the noise is the catalytic converter when its cold out. They say it expands and can make that noise in that RPM. IF it was an engine problem then it would not just do it at high rpms. I thought it was the Cat as well though so thats why i wasnt too worried.

9kredline

I called another mazda dealer in AZ, because i figure they have seen RX8 with engine failures before. Well one of the service techs told me it could be the splash shield and this is the 2nd time i have heard this.

Honestly I am not sure who to believe.

mysql101

yeah, it's anyone's guess unless they hear it in person, or you have a recording we can listen to.

Romeo

Perfect!!!

This is exactly the sound that Ive been hearing since I went turbo!!

Ive been posting like crazy trying to get an answer.
I kept describing it as a "Grinding sound" but now that you mention it. it IS like a beer can being crushed!

I highly think its the cat also.
When I put the Turboxs racepipe on, i didnt hear it anymore (but then again, i could bearly hear myself think) that sound really annoys me and makes me thinking my car is about to blow up. now that I know that there are more threads on this "marble in a can" issue. i'll read up more on it and see what i can do to fix it.

it cant be something "normal" at all...
its definetly not normal.

infact, I feel that i lose power when it does that sound.
i'll post some updated if i get more info that might help.

mysql101

Keep in mind the chances of a NA car being damaged by detonation is a lot less than yours will be with a turbo on it..

9kredline

I am going to Monetreal today so after i come back i will take the car in agan and have them drive it. I want the sound gone!

ps. I dont think its doing anything bad, but there must be a reason. I know its not comming from the engine and is somthing under the car, right above the cat

mysql101

you know your engine is right at the bottom of your car, right?