kd7gab

After a lot of searching here I am starting to be concerned about the engine in my 8. I have an intermittent noise coming from the car, under load only. It sounds very similar to an exhaust leak but I have gone through the exhaust and just had it inspected. Exhaust guy suggests that it must be something else (he does know what he's talking about). This noise never happens on short drives or when the engine isn't too hot. I also notice a loss of power when I try to drive when the noise is present.

I have done the following maintenance/troubleshooting recently:
New plugs
New wires
New coils
Replaced the manifold gasket
aftermarket cat/mid-pipe - Brand new 3ish weeks ago
ECU reset

After each change the noise goes away for a week or two but then comes back, slowly at first. No CELs are thrown. The car died on my fiance on her way from work a couple of days ago.

From my research I have suspicions about the engine compression?

Thanks,

Jon

champi0n

iTrader: (1)

sounds a lot like the problem I'm having. I've done the same fixes yet it persists... Only when the car is at normal operating temperature is when I notice.

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DarkBrew

Without hearing the noise it's hard to make useful suggestions.
Any CELs?
When you say exhaust leak you mean a ticking sound?
Sound samples and suggestions in here.
https://www.rx8club.com/showthread.p...king+sound+SSV
Please follow all the way to page 2

Vader76

Might be the fuel pump overheating and causing the car to run lean

kd7gab

I am hesitant to say the fuel pump makes any sense. This happens regardless of fuel level in the tank. Most in-tank pumps that I am aware of use the fuel to cool themselves.

I have had the car into a dealer, they pulled a code regarding a stuck shutter valve. After replacement the car does have more power but the problem persists. Due to distance constraints I have had the car into another dealer, they're trying to tell me that it's intake noise and nothing more. I will, however, have the opportunity to take it into them and meet with a Mazda rep next week. I also plan to record the noise that the car is making. I'll post the audio clips here when I get it done.

At this point I am starting to think about just trading it in on a new one. The original dealer I dealt with thought the car may need a new short block but I'm not close enough to them to make taking the 8 there again feasible.

SauerKraut

Pretty sure we're in the same boat here... Is it a loud raspy sound? Mine makes it when the car is warmed up, and starts in the higher RPMS. After high-revving it for a bit, it'll start making the noise at lower and lower RPMS over time. I also noice a power loss while its making the sound... Is this similar to what you have?

DarkBrew

Plugs
Loose plug wires or broken insulators can make a loud ticking sound

SSV
Ticking sound from the video above.
You can wire or tape the SSV actuator open and take it for a drive. See if the noise continues.
The SSV involves the valve itself, the electric solenoid, the vacuum actuator the one way check valve, the vacuum accumulator plus any leaks in the VDI actuator system and the air pump actuator.


Exhaust
Running the car it should be obvious if you have an exhaust leak. You'd smell it.

chiggernut

I was driving from philly to delaware. about 1 hour into the trip my 8 decided it didnt want to go past 60 unless i floored it. Major loss of power and a deep bearing type of growl and heavy vibration especially in the the shifter. I pulled over, checked the oil and was about a qt and a half low. topped it off, tried again, no good. checked the coolant reservoir and it was bone dry. topped it off, seemed a lil better. then i turned on the defrost and as soon as the a/c compressor kicked on and the heater started circulating the problem disappeared completely and i was cruisin at 120 again. i have a crack in the radiator directly below the reservior. can be seen thru the grill. also the water pump is leaking slightly out of the weep hole. i believe what is happening is an air pocket forms in the block and one rotor gets hotter than the other a causes a slight misfire and also a rolling idle. I'll fix the leaks and repost.

kd7gab

The SSV is a good spot to look but mine has already been replaced and checked for functionality.

The noise is indeed very raspy, somewhat metallic rattle type of sound. I also see a fairly significant loss of power when it is occurring. Additionally, I also see a very rough idle, the car has stalled a few times when the problem is at its worst.

It most definitely is not a tick of any sort. I will be recording the noise here shortly, I'll try to post a link to the audio files today.

Jon

DarkBrew

Yeah, my post was kind of general stuff...
With all the stuff you've replaced and your current rough idle you really need to check you compression with a rotary specific compression tester. Post the numbers and people here will help interpret the data.
What you can try is
Premixing - this will help your seals if they are bad
Seafoam - this can clean out any carbon locking the seals in place.

DeViLbOi

iTrader: (1)

For some reason I am thinking front O2 sensor or front Exhaust gasket.

DarkBrew

Nice! Good thinking!

kd7gab

I just recorded these about an hour ago. I recorded both the normal running of the engine and the problem noise that it is making. The wave and mp3 files are the same recording, just different formats.

Normal Runs
http://www.mediafire.com/file/8g5w4w...20Compiled.mp3
http://www.mediafire.com/file/u7ib3q...20Compiled.wav

Noise Runs
http://www.mediafire.com/file/zb7aq7...ed%20Noise.mp3
http://www.mediafire.com/file/f2r06r...ed%20Noise.wav

Note this is all from the same outing, the normal runs are just from when the engine was between 195 and 205 coolant temp. The noise generally occurs when the temp creeps any higher.

I have done the carbon removal procedure and it did help the overall performance it did not do much the deal with this problem.

As i mentioned in a previous post I will be meeting with a Mazda Rep on Thursday about the issue. I still have the 100,000 mile core warranty and an auxiliary warranty for the car so I'm not too keen on getting much further in to it. If Mazda denies that it is warrantied I'll just trade it in.

Jon

kd7gab

The front gasket is fine (was replaced during initial troubleshooting) and I have had no codes thrown that are even related to either O2 sensor. I have a computer in the car that I use to keep an eye on things.

Jon

DarkBrew

Very raspy sound...

I'm very curious what's causing this

DeViLbOi

iTrader: (1)

DarkBrew - What are your thoughts on it being a single repeated misfire?

Jon - What type of plugs/wires/coils did you install? And what is your exhaust setup...because DarkBrew is right....YUCK!

DarkBrew

On the surface it looks like he's done all the right things to troubleshoot this.
So we're missing something...
Could it really be leaning out due the fuel pump overheating as Vader76 said?
Other than that I think we have to reexamine all the information, the replacements used etc.
What kind of engine data can you collect?

DeViLbOi

iTrader: (1)

If it were too lean I would expect a sputter or a CEL...not a constant issue like the sound clip has. But yea...data like AFRs and the like I am sure would help.

DarkBrew

Yeah, without data we're running low on ideas....

The weird issues with this car!... there are so many we should compile a list of typical symptoms and solutions.

kd7gab

The wires and plugs are both NGK and as far as I know there are exact replacements. I compared, visually, the components as I replaced. The plugs were the same model as what came out, also what is listed for the car. The wires were identical to the factory wires. The coils also are identical to the originals.

The cat is a RP SuperCat. Note, this did not affect the problem in any way. The exhaust is stock, aside from the SuperCat.

All of the replacements were purchased to be direct replacements and identical to the previous units. The plugs were not fouled when replaced but did appear well used.

At this point all of the info I have come across is point to a seal failure in the upper end range of the normal temp range. The first dealer that I dealt with mentioned that this could be one ignition cycle leaking into the next causing an early fire (detonation). The then suspected the SSV and did that replacement. I was unable to use them again due to distance.

I did have a Typhoon intake on the car. I pulled that back off after I got my OBD reader for the car computer installed. I had noticed way higher intake temps than I was comfortable with. The removal had no effect on the problem. As far as the dealer know there was never an aftermarket intake on the car (they'll complain less...).

If I had access to a rotary compression tester I would post those results but I am limited in tools and budget at this point.

If the dealer does a test I will plan to post the results when I get them.

I can poll data from the car. Maybe today, we'll see how things go. I can connect the laptop in (harder then it sounds) and get all data I can during normal behavior and the issue at hand.

Thank you all for your input. SauerKraut does the noise match what you are noticing? chiggernut, i keep a pretty close eye on my oil and coolant and have not noticed either drop by any significant amount, this is one of the few cars I have owned that does not leak . champi0n, have you had any luck? Does the sound match yours?

Jon

champi0n

iTrader: (1)

Omg yes same noise!!!! Ok this is def the same problem i have... i also feel its heat related.. its normal for the first few minutes of operation then starts sounding like that rasp under load.

DeViLbOi

iTrader: (1)

champi0n - do you also have the RP SuperCat?

kd7gab

Please note that this problem has stayed the same with the stock cat, a midpipe and the supercat. Exhaust changes of this nature have had zero effect.

Jon

champi0n

iTrader: (1)

Agreed. I bought the AP midpipe thinking clogged cat, but nope. Same noise/problem persists.

I hate my car right now because while "drivable", i cant actually drive it

DarkBrew

Cooling?
High water temp makes big air pockets and causes hot spots causing the issue? Flush coolant
E shaft pellet is stuck closed and preventing rotor cooling? Tougher to change...