JCC

I had a strange thing happen on a long drive in New Mexico. I had downshifted into 3rd on a hill bringing the tach up to 6K. The engine went flat and there was a rattling noise like piston ping with low octane fuel. To accelerate I had to upshift to lower revs, it was that bad. No check engine light and plenty of oil and I know I had 91 octane gas. It was about 82 degrees outside and I was getting 24 mile to the gallon on this trip. Anyone else had a similar experience or know if rotories can ping??

Hercules

How many miles on your car?

wakeech

of course: any internal combustion engine can detonate.

how long would you say your engine was "pinging"?? i sincerely doubt that if you tested it to accelerate before downshifting that the motor would've lived that long, nevermind living to tell the tale.
hit up your dealer, try and recreate it.

anyone thinking ignition misfiring?? 6k is pretty high, and i thought there was some saw-toothing on a few of the latest dynocharts...??

JCC

Hi and thanks for the replies. I had about 1500 miles on it when this happened and had use up to 6 - 7k rpm during breakin. I had noticed the 6.5k hesitation a few times but there was never a noise before. This car pulls strong at 4k even at Colorado's altitudes but the "pinging" was at higher revs and lasted for maybe 5 seconds untill I backed off and shifted up to drop the revs and then accelerated again. On a piston engine I would have expected the oppisite with ping at lower revs.

I'll have to wait untill after Sevenstock but there is no hint of a problem now

j9fd3s

na's seem to be more tolerant of detonation, my gsl-se pinged for a long time before we figured out what it was

mike

jem777

Yeah, I had the same thing. At about 500 miles on an incity highway. I got up to about 55 and it was pinging like crazy. I thought a bolt came loose. I slowed down and it stopped. Haven't heard it or been able to recreate it since. Only using the best gas.

Dookie_Rx-8

Hey i think my car does something similar with that rev stuff. Stupid stuff like this makes me hate the rx-8. Im noticing alot of reports about engine problems.

Dookie_Rx-8

u said u found out what it was, then what was the problems

RX8-TX

Alright, if I lured you in here I've achieved what I wanted.
I will appreciate the following information:

1. What is engine PINGING?
2. What symptoms it might have?
3. What consequences does it have?
4. How to detect it?

As you have already guessed, I know as much about Advanced Quantum Physics as of Practical Mechanics.

Thanks to any generous soul that is willing to help!

Psychofox

i experinced the same thing last night. every time when i reved it to about 6k rpm, the pinging sound appeared. it happened in all the gears.. i dont know what's wrong with it since this is my first car..
my car is having 950 miles on it right now

wakeech

i dunno what's up with you guys, but i'll say it again:

i seriously dont' think it's pinging if you're trying it in all the gears, testing to see how far over 6k rpm it'll go.

wakeech

the 13B-MSP comes with knock sensors (2 IIRC), and would be blown to smithereens if as much pinging was happening as is claimed... i dunno what the issue is with those fellows in the other threads, but i have serious doubts about it being detonation.

Spin9k

I've occassionally heard a sound like this at 7K+, typically when I'm hard on it in 3rd gear. Sounds like a rattle or marbles or hard to describe. Not very often, once in 10 runs maybe.

My first thought would be detonation, but why at high RPM? A more likely cause would perhaps be something to do with the intake airflow getting screwed up at hi-revs.

Isn't there this valve that opens between the two intakes abobe 7250 rpm to give explosive compression of the air back and forth between the two rotor's intakes? S-DAIS or the Sequential Dynamic Air Induction System (read all about it in the RX-8 pre-order book) it's called. Maybe if the air gets out of sync in some way.....

JCC

Hi All,

SpongeBob (my 8) made it to and back from SevenStock without another power loss and "pinging' type sound. Had fun in the mountains and desert making use of the gears and revs. I talked to several people and true detonation in a rotary is scary loud - not the metal rattling sound I've heard. Also I tried various octane gas, even as low as 87 without a problem. I bet some of you are noticing a light rattle at slow acceleration but without the power loss. I don't know what that is but it is probably not dangerous. The power loss + noise could be compression loss from carbon sticking one of the apex seals. Can the apex seal make a noise when it's unhappy? If my dealer finds stored codes from the knock sensor or I get more insight I'll post.

John

JCC

If the intake air flow was reduced by bad intake pulse timing then "ping" and detonation would be reduced too. If heated intake air was getting in instead of cool outside air the ping would increase. Piston engines will "ping" with hot air, lean fuel and advanced ignition timing. The 8s ECU takes care of fuel and timing but there is a intake flap for cold air if I remember that could stick. Still, I can't believe the difference between under hood and outside air temp would cause "pinging". I'm using the word "ping" as a less severe form of detonation but inthe rotary this sound may be from something else entirely - I hope

dvcn

JCC-
Sorry, this is a bit off topic but your car was my favorite RX-8 at Sevenstock. You had some Texas-esque bug splatter on the front of your car that impressed me so much that I actually had to take a picture. We were tempted to drive but the new car smell would have been replaced by much uglier ones over the course of the 2700 mile round trip.

wakeech-
How many NA rotaries have you built/tuned? Leaning out and pinging does not cause instant death on an NA. Yes, it's a different story for turbo or nitrous cars.

Pinging NA's that I have seen have been a result of gross ignition negligence or spark plug carbon buildup causing pre-ignition.

wakeech

*BALEETED for politeness*

as you were saying, there doesn't seem to be a real reason that these cars should actually have any detonation in the first place: they're running FAR higher than necessary octane fuel, we know for a fact the ECU is running severly rich in the upper rpm ranges, and there's no reason to believe spark timing is something like +30* advanced...
there are just so many "that doesn't quite seem right"'s that this is all probably not pinging.

r0tor

iTrader: (1)

I've been noticing some pinging like sounds at low rpms... i thought it was true pinging at first but I seriously doubt the engine would still be running since it happens frequently. I'm guessing something is loose somewhere, I'm beginning to wonder if its the clutch ?

canzoomer

I have heard pinging on an RX-8 ( don't ask, OK?)

The anti-knock sensor made it stop right quick.

It is not something subtle. It is loud and sounds like this:

Take a couple or 4 marbles or ball bearings.
Put in large metal coffee can
Shake vigourously

BTW, to make it "ping" on 91 octane you have to advance at least an extra 6 degrees, while running VERY lean fuel/air mix, and at above 5,000 rpm under WOT conditions ( at 2,800 ft. altitude) under very heavy rear wheel load.

Not frigging likely to happen in the wild unless your car is hosed, and by then the ECU would have shut things down to "limp home" mode, you would have no bloody power, and lights on the dash would light up like Christmas.

And doing it once or twice, while frightening sounding, does not trash the engine.

deadrx7conv

Pinging sucks. Was expecting more power from an ECU upgrade but seems that Mazda is extracting plenty.

It would be a good time to clear out all those leaves/rocks/debris from your radiator and oil cooler. Also, switch gas stations. Sounds to me like the gas station you are using is making high profit not really super superunleaded sales.

Keep your oil topped off. Check level off antifreeze and possibly thermostat function.

Anyone with consistent detonation or pinging sound should give redline water wetter, royal purple purple ice, 40-below, or other coolant improver a shot.

mikeb

I hope I never find out what pinging sounds like

Rick

I would not push your luck but I bet you already know that. I have read several stories of rotary being tuned to lean on the Dyno. Their engines were trashed W/little knock.However, the engines where under boost.

canzoomer

If you lean it down you also HAVE TO monitor the O2, the temperature, and so on. We added a pyrometer and a sensor to the exhaust right before the factory O2 so we could do this. Then we dialed up to lean until we got a ping under load, and right after we did the ECU got a signal from teh knock sensor.

We did this on the 5 main fuel/intake configurations that occur at the various rpm points.

After that we enrich the mix enough that 89 octane would be safe, then we filled the tank with 89 and did the rest of our tests that way, keeping an eye on it as we went to confirm we had no further knock.

It is equally important to monitor the exhaust temoperatures as it is quite possible to overheat the stock exhaust..

Our goal is to make the mods safe for mid grade 89 fuel.
87 will be too low for our setup, I can guarantee that.

We are also working at about 2800 foot altitude, so that buys an extra measure of cushion too.
Pre-ignition detonation occurs sooner at lower air pressure levels.