Winning 8

rotary engin have only one knock sensor which locate in the front rotor housing, there for most of the time the rear will go first.
turbo with low compression & na with high compression is the same.

Raptor75

Ya I've read them. For me the 87 works great and all I'm saying is don't blindly put in expensive fuel because you think it is better. If it pings, up the octane if not you've just saved yourself some cash.

If your pinging with high octane and the dealer can't fix it what the hell put in the 87 blow the apex seals and get a new engine under warranty.....at least it will resolve your problem;-)

and with that off to bed.

Raptor2k

...

Raptor75

My RX + 87 octane = no pings no problems.

If it makes you feel better putting 93 octane in your car with out ever testing it with 87........knock yourself out, it's your dime.

Raptor2k

Yeah, screw us.

Fanman

Modern cars these days adjust the timing of the cars using the knock sensor that is true, but it is not like your ears needs to hear pinging & detonation before the engine reacts. That's not the way modern engines/knock sensors react. They pick up detonation and react automatically to pull the timing on the engine (lose hp). That will not even be perceptible to us humans, but the engine is doing it. Not like the old carbed engines, where you are sitting there fiddling with it yourself.

As for losing performance of 5-10hp, human perceptions would not be able to detect it, doesn't mean it isn't there.

See the Car & Driver article I referenced in several of these threads. On high performance cars with high compression engines the loss in performance was substantial. The new Renesis engine has a higher compression ratio than the old 13B's (10:1 vs. 9:1).

Some people have gotten detonation/pinging when running 87. Hence, like I said you are at th bottom end of the acceptable range of fuel. The engine/KS/ECU simply can't pull anymore timing, so you start detonating.

Raptor2k

Any idea on why pinging could be happening while running 93?

https://www.rx8club.com/showthread.p...6&page=2&pp=15

yiksing

Fact:
1. If it doesn't ping at a lower octane, it will not ping at a higher octane unless something else is wrong.
2. It doesn't improve power if you go higher octane if your engine is tuned at a lower octane.

Raptor75

Hmmm....not fun.

Here are some ideas for what they are worth.

- How many miles on the car. You could have carbon build up in the engine, which is causing the knock. This would be difficult to fix with out a tear down.

- There could be an issue with your time advance/retard system causing the engine to run out side the safe zone.

- It could be an unrelated rattle that resonates around 7 to 8K.

- To put the octane issue to bed go to a auto store/speed shop and get a can or two of octane booster. If your pinging with this you can at least tell the dealer it is not the fuel quality.

Dose the pinging happen while cursing or just under acceleration. Acceleration will increase the chance of pinging. Out side temp will also affect the chance of pinging. Are you getting good fuel mileage? If so maybe the car is running too lean because of a faulty sensor. My car's mileage sucks and runs very rich, I sure this contributes to my lack of pinging.

If you can find someone in the area with a Scanaliser or other type of engine management reader you can see what the fuel mixture and timing advance is when you get the pinging.

Good luck, it dose sound like you have a legit problem the hard to detect type which Mazda loves to avoid.

Raptor2k

I just hit about 20k....there have been posts here that it could be a clogged cat causing it, not sure. I drive the car hard, I redline multiple times daily.

I thought about the octane booster, but I need to go in for my 20k service so I'll tell them about the rattling still being there. Last time, they told me it's probably bad gas from the particular gas station I've been going to, so they recommended me to some and I've had 3 tanks since then, but there's been no differene. Other than that, they had one rx8 which had its tank drained and then they put in high octane gas and it went away...so we'll see.

I get about 17mpg.

If I cruise while I'm at 7500 rpms, the ringing will be constant. And of course, it's there when accelerating when I'm about to redline (it comes right before the buzzer).

I'll go to the dealer tomorrow and get this over with, I'm pretty much free the whole day.

zoom44

its not engine knock then. if you cruised at 7500 rpm and got constant engine knock you would foul the plugs so you would start getting misfire CELs. Plus you'd get emissions CELs as the fuel wouldnt be getting burned so the O2 sensors would catch that over rich situation. All of this would cool the chambers and stop the knock.

Raptor2k

Then what could it be?

Raptor2k

I went and they told me it's normal, and they've had the same complaint before. How is it normal if I'm the one of the very few who have the pinging? I also don't want this to hurt the life of the engine.

They said their technician can run some tests, but it would take half hour, which I didn't have time for but I'll get it done later.