Manic Mechanic

MAF was cleaned a while ago, apart from a light dust it was fine - no change.

SSV and VDI valves are as free as can be, easily moved by hand or by applying light vacuum.

Compression was just checked last month by a rotary specialist, he heard the rattle and looked but couldn't diagnose the problem either!
Lambda readings suggest fuelling is spot on, even right up to the rev limiter. Has 42,000 miles on the clock.

Anything that reduces the octane inc. premixing makes things worse.

The CAT is fine front and back, emissions perfect, doesn't glow, you can see the honeycomb and shine a light through from the rear end.

Is it possible that some RX-8s 'just do this' ?

champi0n

iTrader: (1)

Lol, no.

There's some underlying issue which causes power loss in the form of something not happening correctly during combustion cycle somewhere. My car ran great at one point in its life.

Right now it's a crap shoot as to what this is. My current guess is something to do with the fuel system after it's warmed up. (Though it could even be an improper temperature reading or a bug in the ECU firmware).

Dragonfooser

Thanks for the suggestion. I'll try the seafoam and/or some injector cleaner and report the results.

Another things I've notice that seems to be related is that the fan will run for an inordinate amount of time after the car's been shut off. Anyone else notice that?

I know it's got to be unrelated, but I got a new battery, and I swear the problem disappeared for almost a week.

SauerKraut

My fan doesnt run after the car is shut off, but I have the problem. It's funny how changing something makes the problem dissapear for a while, then have it come back. Could it be a problem with our computers perhaps? Idk

champi0n

iTrader: (1)

Ok, I've put together a quick survey/form which will hopefully give us all a big picture view on this thing.

>> Answer a short anonymous survey to help compile some statistics on this issue.

>> View the response summary here.

Dragonfooser

The Seafoam made a huge difference. Car ran well through the whole tank of gas. As mentioned earlier though, this is obviously not a sustainable fix.

Thanks for posting the survey!

champi0n

iTrader: (1)

I'm gonna bite the bullet and buy a new fuel pump (walbro unit if I can find the part number) as well as replace the injectors. I'm almost positive one of the two will solve this issue.

The unfortunate thing is my car is currently on blocks since I busted a few rusty brake lines. I'm guessing it'll be 4-5 weeks before I get a weekend to work on it.

I'll have a small window of time to do some work 3 weeks from now, though if not the next soonest is 5th weekend.

TacoMan

That's exactly the sound I am getting. I took it to the dealer today because it seems like

No one knows what this is ha. When he asked me what was wrong with it he told me that

I will probably get a new engine, but I'll let you guys know what is happening.

DHPrx8

I have been dealing with the same situation for the past year...

My posting https://www.rx8club.com/series-i-trouble-shooting-95/misfiring-fuel-starvation-video-sound-attached-204603/ I have a video/audio file on there two that really lets you hear how bad it can get!

I just put the new fuel pump in from BHR - didnt solve a thing. My first post has a listing of all the things I have tried. I am down to taking out the injectors and getting them tested and cleaned.

If i put in a bottle of MAG1 fuel injector cleaner with a half tank of gas I can get it to pretty much go away for a short time and then it comes back.

DHPrx8

Champion - Great Survey! Interesting that the only thing no one has replaced in trying to fix this is the fuel injectors. I am trying to get time to get mine tested and cleaned - will let you guys know what happens.

champi0n

iTrader: (1)

Considering we're all relatively "high mileage" 2004's, it's likely we're the first batch to experience this problem. Hopefully the injectors are the solution and we can put this thing to rest.

The survey really puts it into perspective, even given the relatively small dataset. But fuel additives seemed to be the only thing which might remedy the problem; and injectors are something no one has yet to touch.

I'm not sure a test on the injectors would be entirely fool proof, as it could be a mechanical failure related to heat where the injector can't keep up with demand.

But please do let us know how the injector test turns out and what was done to test (ie just an OHM reading, or full featured test bench).

I'll be away for a few weeks but when I get back I'll be installing new injectors regardless.

Chris

iTrader: (10)

ok so my car has made what I think is the exact same noise. kinda sounds like a flapping or exhaust leak. This is gonna sound extremely rare, but I cleaned the maf and now the car runs smooth and noise free

I did notice I had some blow back oil so I think that it was really gumming up the MAF. and my problem got worse with the warmer my engine would run. What I think could cause the massive power loss would be poor reading which could possible cause the ssv to open at the wrong times per real airflow, ie too little air or too much air causing the AFR to go lean and get ping/detonation or go rich causing bogging, but that is an idea of my own, could be way off here

TacoMan

Well my car has to get a new engine because of this sound I guess. The dealership called me and

said I had low compression and also have to replace all four oil injectors which is 400$ for all four

which is way better then paying 2000$ for a new engine. If you guys have this noise I would take the car

in because you probably have low compression and get a free engine :]

TacoMan

Btw my car is a 2006, with 40630 miles on the engine. :[

Footman

iTrader: (2)

I have the same problem now.

2007 car with 85000km.
Stock intake, stock CAT, MS exhaust
New coils/wires/plugs last changed at 72000km. I've verified it's not the exhaust issue as I had recently had it welded up to fix cracks.

The noise is the same as the posted videos, happens in the upper half RPM range only when you gun it.

It happens after the car is warmed up and runs hot. The car has never had coolant flushed yet (still on stock fluid from when the car was new). I've been monitoring the coolant lately as I feel its running hot, in city traffic, it stays between 93 and 100 C.

I have an appointment tomorrow to have the coolant flushed/filled. I read that the car should be kept around 82 - 85 C in city driving. The car has no problems at idle. The MAF sensor is cleaned twice a year, and I recently just cleaned it again.

I hope there is some solution to this, as I wonder if I need a new engine or not.

stevep200sx

Folks, just wanted to add my car to the list of 8s with this same problem in case there is strength in numbers and well, misery loves company. I'm not contributing much to this thread yet, I know. My girl is kick *** until I've been on the highway for about 30-45 minutes and then it's marbles in a can and a disheartening lack of power. My car is stock, '04 6speed with about 100,000kms (not miles) on it and I'm on the east coast of canada. Like others, I've changed out plugs, wires, coils, watched oil and coolent levels, and most recently, the dealer thought it was a neutral switch (got the CEL light, code, changed it, and of course it wasn't the neutral switch). Anywho, this particular thread seems to be the most recent and most scientific so I just wanted to thank everyone for their hard work tracking this down. From my studies here, just to sum up, here's what it seems like everyone agrees might be happening. Either or:

Dirty MAF
Stuck SSV
Injector problems
Misfires (though most don't agree it seems)
Low compression

I'm going to the dealer with this and will try to help them track further and if I get anywhere, I'll post. It seems that too many people are experiencing this for there not to be an answer around the corner.

Citrik

Yeah definitely keep us updated if you can. Hopefully they don't just say you need a new engine because that really doesn't help us out at all. I wish I could play the guinea pig with my car as well but I just don't have the funds for it right now, so trust when I say that your effort and info is appreciated.

SauerKraut

I and others have cleaned the maf with no change... I've gotten a misfire code, so thats potentially happening, but not always. I'm really waiting to hear back from the guy who is changing out his injectors...

adore56

Just to tell you guys i have the same problem 04 gt mt 80000kms just noticed it after installing typhoon intake.

stevep200sx

Ok, fun update of my saga. Took a work trip Thursday to a city 3 hours away. As usual, bucking and surging and noise after the car got hot. I noticed the oil was low after I arrived, put more in (looks like maybe too much) because on the way home, the power was gone from almost every gear and the three hour trip was absolutely horrible. Check out the pictures....I got home and thought that swapping out my k&n air filter and putting back in the air box walls would be a good idea if the dealer is going to tear everything apart.

The pictures are of a) my air intake "horn" screen with a finger swipe drawn in the dust (probably not good) and b) the view down into the accordian intake tube behind the air box. It would almost be funny to see so much oil pooled in the grooves of the air tube if it wasn't so worrying. That's probably from putting too much oil in? SSV valve?

I'm going to take apart the air box and try to clean out the MAF, tube, etc. I don't know if it'll help any but I'll update after. Anyone seen oil like this in their intake?

Footman

iTrader: (2)

oil blowback... overfilled oil?

Or overoiled K&N filter?

adore56

i just did see some oil in the intake tube also but the screen was clean

DeViLbOi

iTrader: (1)

You really should take apart your entire UIM and clean out the oil. With that much dirt you are going to need to clean your MAF really well and probably your throttle body. You should also try and clean as much oil off of your SSV as you can.

gavcolton

I have tried removing the vacuum from both the SSV and VDI, the VDI made no difference, however, when I removed the vacuum from the SSV, although the noise did not go away, it was quieter and did not do it as much (also caused noticeable loss of power at the top end).

I reconnect the vacuums and then cable tied the SSV open, but this made no difference and the noise came back at the same RPM (4500).

stevep200sx

It's definitely overfilled oil based on how much I put in. I was on the road and in a rush...lesson learned. That much oil has to be from filling it. I've read that just poring oil into the filler spout can cause this as it runs down the inside of the tube and seeps into the intake. There are lots of posts about oil catch cans about this. My concern is that if memory serves, the first time my car bucked and sputtered and did the marbles sound, I had just filled the oil. It's not sound logic to suggest this is the reason, but if the intake is sludged, SSV valves and so forth are sluggish, it would definitely cause driveability issues the same as any other igniting issues in any car....i.e. air fuel mixture gets skewed and the car limps because the condidtions are less than ideal. And in this sensitive car, it's a lead I'm going to chase and see what happens. Also, forgot to mention that after the 3 hour drive, he car would be hot as hell, but I pushed her hard and redlined half a dozen times and the power came back. It still made the noise, but it's almost like red lining burned off something or forced a vavle to respond better? God, I have no idea.