Astor

I've not experience any knocking, I only use 93 octane, 91 is not available here and it goes from 87, 89, to 93 with about $.10 a gallon difference between each one. I did have to buy 89 once because the 93's handle was ripped off, I experience extra vibration in 6th gear, same speed in 5th and 4th produced no such vibrations.

sferrett

We should probably keep the emotional slants out and attempt to continue this as a technically interesting thread - it would be very easy for someone to interpret the above as a personal attack.

People see me coming a mile away because I'm overweight, not because of the gas I use. I use 91 because that's what the owner's manual recommends, which doesn't qualify as hype in my book.

Maniac's comments on the noise possibly being afterburn rather than knock is interesting - as I said, I've not heard this noise first hand in the '8 so I don't know for certain what people are describing is detonation. Either way, I will continue to go with the recommendation in the owner's manual.

Simon.

ashmason

sferrett, well said, I have to admit I was feeling a little out of sorts with some of the earlier comments.

This is our first Rotary and it's NOT a normal noise. I don't know if it's detonation, I don't know enough about the engine. All I do know is that I floored the accelerator and somewhere around the 6000 rpm mark a horrible rattling sound occured, like the engine was about to trash itself, along with a loss of power.

I immediately backed off the throttle and it went away. I haven't been able to duplicate it since, thogh it happened the next day to my wife, but thats the last time it has occured, it's been running for the last 5 days without a problem.

Sorry to all you folks out there who consider this a waste of time as it's a "Normal" occurence, but you can imagine my alarm as someone who has a brand new car and is not expecting it.

My take is this, If it doesn't do it often, then why should it do it at all?

I am not overly worried myself, however my wife gets all freaked out if she hears something she is not expecting, heck if the check engine light comes on she pulls over and calls me. Trouble is, we bought the car for her, not me... Otherwise it would be a Stick shift, not an Auto!

Still, that said, even negative type comments have a place here as it does lessen my concern. Still engineering and materials in general has come a long way since the RX-2, and consumer expectations are that much higher.

My S2000 has 50,000 miles on it and is constantly redlined to 8900 rpm, but as yet has not given ANY odd noises.

Whew, there, thats off my chest now.

8_wannabe

Nothing personal, Simon. My post started out as "For those using 93 and higher..." That doesn't apply to you as you're following the manufacturers recommendation. I didn't know you were fat so no slight intended there. I meant what I said and believe this is totally factual: Gasoline companies have created a myth that somehow increasing octane is good for your car. They make a lot of money off those who have succumbed to this myth. It is nothing but hype, but those who have fallen for it seem perfectly content because they "believe" they are doing something positive for their car. All hail the power of marketing! :D I am talking about those who exceed the recommended octane rating for their car, not those who simply comply with it.

sferrett

haha - actually the overweight bit was actually meant as a joke.

"no worries"

Simon

JCC

The knock sensor log is very interesting along with the engine right side location. If abnormal rotor pressure happens from some kind of pre-combustion in the intake phase then maybe the noise is rotor gear rattle This would cause a power loss but would likely look ok to O2 sensors. Maybe the inertia angle sensor used for misfire detection would pick up on this?

Ned M

iTrader: (2)

You describe exactly what I hear and never under load; only while cruising in 3rd or 4th. With the passenger window down and driving alongside a sound-reflecting wall or concrete divider, I can't hear the sound coming back from outside the car like you can with a piston engine that's detonating. My guess is it's elsewhere in the exhaust system, but it is disconcerting. My 3rd gen has never made that sound (altho its tranny is also noisy like the RX-8). Thanks.

dunno

listen up all you prior rx-7 owners, if you think this "detonation" noise upon acceleration in the new 8 is normal then rotary engines are a piece of crap. bottom line here is i do not think it is a normal noise and will take legal action against mazda if needed. a new car should never make than kind of noise whether it be a rotary or regular piston engine. 949 222 2638. that is the number all you prudent fellows should be calling right about now.

Spin9k

suggest you'll do better if you lose the attitude ... nevertheless...how about a sound clip? Let's us hear this noise, collectively we may be able to help.

8_wannabe

What should we tell them? That we heard of a guy who is hearing noises? I don't think they'll be too interested in 2nd hand reports. I suggest that we don't call out of prudence, but if your car is making funny noises then by all means call.

Psylence

It. Is. Not. Detonation.

But by all means, please get rid of your RX8, Dunno. I don't want "certain types of people" ruining the reputation of my car.

Oh, and for the 91 and under octane crowd. GET IT THROUGH YOUR SKULLS. Not all of us live in godforsaken Cali. We don't get goat-**** 91 octane as "high-test" on the east coast. Premium is 93.

dunno

i was only referring to those people who are experiencing that particular "detonation" noise. if your 8 does not have that problem, then don't waste your time calling !

ranger4277

I agree.. post a sound of this noise if possible, I've never heard a rotary knock before.

8_wannabe

That is probably me you are responding to, but you got it backwards. Cali is God's country; where else do you get great weather, great beaches, free "shake and bake" from our earthquakes and fires, plus Ahnuld all in one!?

My point about gas is, Mazda does not recommend "premium." Mazda recommends 91. If 91 is midgrade for you, then that's what they recommend you use. Any higher grade is a waste. What perceived benefit do you think you're getting from the extra octane, and what studies/reports back up your assertion?

dunno

correction to above, call 800 222 5500. that is mazda's consumer hotline in regards to the rattling / pinging noise that some 8 owners are experiencing. again, if you do not have that problem, do not call. the other number posted is only reserved for written complaints about mazda vehicles.

jonalan

Oh, so you call them to give a written complaint.

8_wannabe

Yeah, I thought that was pretty funny too.

dunno

seems like we have a few sarcastic members here ! you first send in a written complaint then they will contact you about your specific concerns. that is how i got the number in the first place. but that won't apply to either of you, obviously.

zoom44

isnt this just the sound of the intake ports opening? as it spins open it makes a sort of rattling noise. as for the loss of power at WOT could it be lag time between the moment the rpms pass the specific point and the time it takes to open? i have never experienced any sort of power loss in my 8 nor knock. also perhaps there is some "sticking port" issue that we all heard rumours about on pre-production vehicles.

JCC

I like your theory a lot for the high power engine. If the rotary barrel valves sometimes stick, rattle and not open fully this covers the observations. However, the low power engines do not have 3rd port barrel valves so maybe there are 2 different noise/power issues? Here is an Australian pic of the barrel valves.

dunno

do any of you rotary engine enthusiasts know if a rotary engine has something called an egr valve? (exhaust gas recirculation)

zoom44

wow great pic thanks.

jonalan

No, there's quite a lot, actually. It's all done in fun, though (hence the ). Please don't take it too seriously.

Shamblerock

Well, I just started to hear this light knocking (marbles in a can ) sound at aroun3,000 - 4,500 RPM under light acceleration in the first few gears. But I don't feel a loss of power at all under full acceleration and I also don't hear the knocking either. It just seems to be in that 3-4.5K rpm that it happens or is most pronounced.

This happen to me once before a few months ago but it went away. Now its back.

Here's a theory to take into consideration: The buggers at the gas station mixed/blended the gas octanes or filled the "premium Tank" with regular fuel. Basically, you think your pumping 91 octane but its either 87 or something in between because they screwed up or tried to save a few bucks by blending octanes.

bxb40

When the car was new, I could use 87 octane. Then at about 4000 miles, I started having detonation underheavy acceleration at high RPMs. I switched to 89 octane and it's all gone. I do have other noises - probably a loose cat or at least the shield on top of it, and some wirl noise proportional to the RPM when just touching the acceleration (water pump? other bearing? the air pump? dunno, dealer mechanic says it's normal... though 3000 miles ago it was not there). So.... it is somewhat a noisy car, but if it runs fine and no CELs are there, why bother?!? Oh well.....
But if it is detonating using 91 or 93 octane I would take care of it for sure. No engine would possibly like detonation....