I had a high RPM rattle since the day my 8 was new. I ran nothing but 93 octane, and the noise happened every single time I ran it to redline. You'd hear a "Bzzzz! Bz bz" noise around 6K, then it'd dissapear until around 7200 when it'd come back steady until I shifted. (And don't tell me it's normal, I own a 72 RX2, and used to have an 85 GSL-SE. I know what a rotary sounds like)

I spoke to my long time mechanic friend at my Mazda dealer (who is Rotary Certified) and he told me it is detonation, and there's nothing you can do about it. I had a theory regarding the ports on the S-DAIS opening, but never got around to testing it before I traded the car.

Perhaps someone would like to unplug the wires that operate the S-DAIS and run it through the gears disconnected? I believe that may be the cause of the noise.

 

I have noticed the same noise at 6000rpm. But what I did notice is the noise doesn't happen if you slowly accelerate up to 6k and beyond. Get on the throttle and there it is. So doing this a few times did lead me to believe it is the ports opening.

Whoever experiences this noise try accelerating slowly and see if it is still present. I didn't hear it when I did it, but when I stepped on it I heard it.

 

Yep, mine behaved exactly the same, which is why I was suspicious of pre-ignition. I believe the S-DAIS operation is not affected by throttle, only by RPM. If that's the case, it's knock, or just a resonance caused by the rush of air at WOT. If the S-DAIS is throttle position sensitive, I'd say it falls into the range of normal operating noise.

 

I just read the entire post and I’m feeling much better now. I run 87 octane, it is winter and we have oxygenated fuel in Maine. I have 2500 miles on my car and get 18-21MPG. I shift at 4K normally but have heard it beep a few times too and I haven’t heard a sound that has caused me to worry yet!

Has there been a poll done yet that correlates octane to knocking? If not maybe there should be so we can get some real data. I’d think there should be 8 options:
I use 93 and have no knocking
I use 93 and have knocking
I use 91 and have no knocking
… And so on.
I use 87 and have knocking

Good idea?

 

Yes. Set it up! I'll post my experience as well.

 

From hagar852 "But what I did notice is the noise doesn't happen if you slowly accelerate up to 6k and beyond. Get on the throttle and there it is."

Yes I noticed this today as well. I don't get, or take, the opportunity to get on the throttle often and thought I heard something in the in the past, but today the above behavior was pretty obvious.

Kind of a "clacking" noise? Hmm... it sounds sort of like the noise under the hood when I shut the car off, which only started happening after the "M" flash.

I forgot what causes that noise, something to do with a gadget that releases the fuel pressure or something to prevent flooding. Sorry, I'm too damn lazy to do a search.

 

Obviously there is enough of this going around (mine does it too). Has anybody had engine failure do to this. I just hit 4k miles when I started noticing my sounds.

Whats the latest flash? I had one done 2 months ago.

 

I have an april o4 build date with manual trans. Notice the ping nearly since purchase, now have 2,700 miles. Still happens at times. I notice it at low speeds, 2nd and 3rd gear at low rpm and moderate throttle. Car runs great, though. No hesitation. No knocking and plenty of power at higher rpm. Will continue to monitor the engine and check back on the forrum. Any suggestions are appreciated.

Ryan

 

To add my 2 cents worth, I have been very patient with my RX8 and it has been back at the dealer twice now. It is very easy to duplicate the knock - either find a nice piece of highway and run WOT in 1st, 2nd to the redline then change to 3rd and keep your foot flat - at about 80mph the knock will start - sounds just like things are going to explode.

Now for the guys who say, one email and it's panic, I live in Denver so the next acid test is go up into the mountains and find a really steep grade and hit that full throttle in 2nd then 3rd - as I told the dealer, when you need the big dogs Zoom Zoom runs for the kennel plus really want to expolde (you have to back off the throttle)

I love the car but after the last visit to the dealer, 3 days of trying, they retuned the car to my wife saying they could find nothing wrong so give it a try and see what it's like.

This is going to sound VERY wierd but Zoom Zoom has been great untill this week end when i checked the oil and founf the oil cap lying loose in the engine bay - put the cap back and guess what - the noise is back.

Any ideas or feedback is welcome.