Ok guys, this is getting weird/frustrating. Took it back to the dealer, and what they are telling me makes no sense at all. First off, they are saying that compression is in the 9s, at 250 rpm, highest values are 9.8 and 9.5. That alone is unbelievable. Second, they are still insisting on the intake manifold, saying its carbon in the runners making that noise... Does the 2nd video I linked above sounds like freaking carbon in the intake??

Apparently a new LIM costs $2772 USD and there is only 1 to be found in the entire country. That and pulling the engine and for that amount of $$ I might as well get it rebuilt. Or they can replace the SSV alone but are not guaranteeing it will fix the problem. But the real issue is they are refusing to acknowledge the pinging/knocking. I think I'm going to go there tomorrow morning and insist the tech goes for a drive with me.

Decarb??

Already tried that. Didn't make too much of a difference.

Please help diagnose pinging/detonation
 

Boroscope to see how your rotors look?

Double check your plugs are not reversed. And wires are in the correct order.

Sorry I'm in a customs line and can't easily go back to see what's been done. I'm working from memory.

That dealer is just making shit up as they go along. Have you verified your pinging VIA a datalog?

Would I look for it to pull timing or some other sign? It didn't seem to be pulling timing in the log I posted on the previous page. My only "real" verification is that if I run straight 100 octane race gas it does not do it. Also that it is sensitive to the engine temperature.

Is there any may you can just log AFR and RPM? That log is tough to read but based on what I see, it should not be detonating. It could possibly be preignition.

Have you pulled the plugs and looked at them? Also, have you checked the cat converter?

Please help diagnose pinging/detonation
 

Hence why I asked about decarb ing and 7 heat plugs in the trailing position. Or possibly swapped leading and trailing wires.

I've been eyeing this thread from the start. Didn't say anything because I don't know anything about this matter. So, any updates? Did you get it fixed? I'd love to know what caused all this.

Hey guys,

I've been really busy but I recently spent some quality time under the car and I owe you an update. First off, here are the compression numbers form the last visit to the dealer:

Rotor 1: 8.6, 8.8, 8.7 (@250 rpm)
Rotor 2: 8.8, 9.0, 9.2 (@250 rpm)

This is a re-man with 12k miles on it. Seems a bit too good to be true, but it does make me feel better. Or maybe those numbers are total BS and I'm just sticking my head in the sand. :iwstupid: At least now that the warranty is out on this engine, I feel free and never have to deal with dealer BS again.

During the past several weeks, it has gotten colder and it started misfiring more on cold starts, to the point of setting P0300 and pending P0301 every few drive cycles. However, it did not misfire when warm or when under load. I thought, "aha, maybe I have an ignition problem". I checked that the right plugs are in the leading and trailing positions, and connected to the correct coils. I tested the coils and wires with an HEI ignition tester, and all of them tested good. (Age of coils & wires - 13k miles). I also pulled the plugs. They looked fine to me (layman), but I'd be interested to see what you think. The plugs shown have 4,000 miles on them. It looked like the tech that re-installed the plugs used oil on the threads, some of it got on the tip of the plug when removing. I blasted it off with MAF cleaner before re-installation.

Rotor 1 leading:

https://cimg9.ibsrv.net/gimg/www.rx8...5723006028.jpg


Rotor 1 trailing:

https://cimg2.ibsrv.net/gimg/www.rx8...8b9b4c7644.jpg

Rotor 2 leading:

https://cimg3.ibsrv.net/gimg/www.rx8...c4b71f826e.jpg

Rotor 2 trailing:

https://cimg4.ibsrv.net/gimg/www.rx8...2d5096cc88.jpg

Incidentally, after re-installing the plugs, the cold start misfire is gone. But now my idle LTFT is up to 16%. Today I checked the torque on the plugs, and all of them were tight.

So in summary, I seem to have established that I have good compression and my ignition is healthy. Today the temperature was 80 F outside, and the detonation was back in full force when climbing uphill. In my mind there are 3 things left to check, before starting on the road to pulling the engine: mystery vacuum leak (but it is not showing lean when the detonation happens), incorrect fuel pressure and clogging of the cat (though I fail to see how it would cause detonation, but not obvious bogging/power loss). As always, I appreciate your feedback!

Today's update:

Took a look inside the catalytic converter. I was surprised how good it looked for having 100k miles on it. It looked almost new, with no carbon that I could see readily. The matrix looked perfect. So I think together with my prior ignition inspection, this rules out a faulty ignition.

Also had the fuel pressure tested. The fuel pressure at idle was 59 psi (a bit low but within 54.4-65.2 psi specification) , and the fuel hold pressure was 29 psi (per specification). So the fuel pump isn't obviously the problem... but could it be not delivering the required pressure at higher load/ after extended operation? The mechanic seems to think my fuel trim behavior is consistent with a failing pump, but if the detonation is caused by a fuel delivery problem, I would expect it to be running lean when it happens, and it's not running lean. :scratchhe The only time I see it running lean is at idle once warmed up.

So the only other possibilities remaining seem to be weird vacuum leak that only affects one of the rotors, as previously mentioned, or carbon buildup that can only be cured by a re-build :( I am willing to try a new fuel pump before pulling the engine, but I am not hopeful it will help.

May 5th Update
 

Time for another update. Took it to Neptune Speed in Huntington Beach. The master mechanic believes there is a leak at the LIM gasket. He took off the upper manifold and pressure tested it, and there were no leaks there, which leaves only the LIM. I think this is the diagnosis most consistent with my low MAF reading at idle, the fluctuating idle under electrical load, the idle fuel trims that will sometimes go up to 14-16% when engine bay is heat soaked, but then go back down a day later... Kudos to Brettus :worship: for putting forth the theory months ago.

EDITED after picking up car

Unfortunately, this is the most expensive fix short of an engine rebuild, as it does require dropping the engine. I was ready to set up to do this and fork over the money, but Yoshi-san does not believe that light detonation is harmful to the engine, based on reports of similar problems in JDM Series II RX-8s, and that Mazda basically said there is no fix for it. I might have been freaking out too much over this. Can I justify the $1200 cost of dropping the engine to replace the LIM gasket if there's no significant harm being done in the current condition? Probably not right now, as long as it doesn't get worse... A more economical approach may be to improve my detonation margin by making sure my water and oil temps are well managed, maybe throw a new front O2 sensor at it (still on the original @ 118k), maybe BHR ignition would help?

So on the way to work today, was getting MIAC sound, except this time it was between 5500-6500 rpm and sounded different. Like a metallic flutter, where the can with the marbles is shaken with a regular interval. Seemed very much rpm dependent, and would stop by 6500 rpm. I could accelerate through it in 2nd, 3rd and 4th gear. In 5th gear it bogged, and I noticed flashing CEL (misfire). Have pending codes P0302, P2004, P2005. (Yes I checked what they mean, both APVs stuck open.) Next drive cycle P2004 & P2005 cleared, and I could not get the problem to re-occur in 2nd -4th gears.

Not entirely sure what to make of this: if this is an unrelated problem, another consequence of LIM/LIM gasket leak, or actually points to root cause. 8k miles ago, coils & wires tested good, plugs and cat looked good as well, but I think I have noticed noise of this nature before and just thought it was more detonation.

Scared, please help
 

Tonight i was driving my 04 auto home from work. I accelerated to 120km (after it was warmed up) then let of so the car was slowing down, once it got to about 90-95km it sounded like it back fired or something shot out the exhaust, jerked back and forth 2-3 times, then went back to normal as if nothing happened. Car starts hot and cold in under 2 seconds as i have just replaced the engine with a used one about 3 weeks ago (old one took about 15-30 secs cold to start, no hot) and hadn’t done this till now. Have not tried starting the car since. Just wondering what this could be and if i should be worried. I did some looking and couldn’t find any situations like this.

That sounds like your cat blowing up. Did you check it while replacing the engine? If it was clogged, that might be what killed your first engine.

I don’t know
 

My cat was melted when I bought the car almost a year ago (june 29) as i could here it rattle. I replaced the mid pipe and muffler with a free flow cat turbo xs exhaust in September. Ill try and see but is it really possible that its gone already? Also I am gonna start the car this afternoon, would it be louder when cold started? How would this cause the car to jerk back and forth and then go back to normal.

Yes. Most off the shelf cats don't live long attached to a rotary.

Thanks, but another thing…
 

Thanks I’ll look into it. Is it also possible for a lot of fuel to get stuck in my exhaust and ignite causing back force to the rotor causing an effect like detonation on it. Im asking this because the exhaust doesn’t sound any different to before (I imagine it would get louder) and it would explain the jerking that happened after.

It's possible and is exactly what happens when you have a clogged cat. Also if it wasn't damaged before, having a backfire go through it can itself be damaging. It doesn't necessarily get louder, the pieces of cat are still in there in unpredictable places. Maybe it's not that, but so far the symptoms fit.

Thanks
 

Ok thanks for the help

Im back…
 

I’ve been looking for a few days now but i have a coolant leak. The coolant is pooling into the little indents on the lower intake. I’ve looked at diagrams and they don’t show any coolant lines above the area its pooling in. Im wondering if any of you know any ways coolant can be getting there and from where. The photos are from my old engine for better visibility so you can see where I'm talking about.
https://cimg2.ibsrv.net/gimg/www.rx8...d359c1f22.jpeg
View from behind
https://cimg6.ibsrv.net/gimg/www.rx8...71d4c3e57.jpeg
View from front (only seems to be pooling in the front indents, non in the far back one).

Pinging happening in R3
 

Hi, I have been following the thread as it has been happening to me. If I use professional octane booster, it would stop but its expensive solution and it causes damage to the fuel pump.
I've did a engine rebuild, fuel pump changed (due to excessive use of octane boosters), spark plug changed and dyno testing and tried tuning but still got pinging issue.
Was the solution to the problem?