Rotor #2 failures/misfires?
 

It seems to me that almost all of the misfire complaints are for rotor #2.
I also have noted that almost all of the failures on both the Renesis and the REW are in rotor #2.
This might be a cooling issue (the coolant has already passed by rotor #1 on its way to rotor#2) or an oiling issue (though the oil seems to go the other way AFAIK) that lead to a greater likelihood of detonation in rotor #2.
I don't think it is a fuel starvation issue since the fuel rails are center-fed and have no return, or a breathing issue since the intake manifold is pretty much symmetrical.
On the exhaust side, #2 is the closest to the end of the line, so the residual temps should be lower.

I've begun adding a few milliseconds to the injector pulse on just rotor #2. I'll see how much more rich I can go before it begins to adversely affect power. The added fuel might have a quenching effect.

Ideas?

No ideas...but it's common from time to time to see aftermarket companies advertising their intake manifolds to be engineered to even flow and temps between the front and rear rotor in and effort to stabilize number 2.

I've always wondered how much those are gimmicks, and how much good they really do...and as you state above, the Renesis intake manifold is "pretty much symmetrical".

edit: actually probably way far fetched and complicated - but I always wondered how difficult it would be to run a separate coolant line into the second rotor - basically a feed for each that could collect after the engine on the way back to the radiator - probably more trouble, complication and machining than it is worth for an experiment. And also because the cooling of the rotors is through oil in the eccentric shaft...maybe have more injection into the rear rotor through the eccentric shaft...I don't know just rambling and throwing stuff out there...

Bah...this is why we need each rotor/housing as a standalone unit that can "lego" to another one's eshaft...snap together for more power! haa haa

One can dream cant they...and no one said that dreams had to be well thought out...

would be interesting to monitor a/f and egt from each rotor --like recips do their banks. OD

You could do it, but the sensors wouldn't live very long.
Independent EGT probes would be more up to the task, but you would have to know what you are looking at for the data to be useful.

back when I had misfires it occured at various times on both, but that was a long time ago

Were your misfires tied to any particular engine fault or condition?
Remember, it is "normal" to have rotor misfires (as per Mazda).

I have yet to drive an '8 in which I can't trigger a #2 misfire. (Except the current motor in mine, but I haven't really tried as yet.)

Really ? .... hmm ...

I never have one ..... am I having a problem ? :Eyecrazy:

Let me drive your car. I can demonstrate.

You could,whenever you visit New york :)

Man if you guys come to New York, I'll show up to watch... and take pictures.

I had misfire codes while breaking in my engine the fast, hard way

that was two years ago and I've never had any since, can't recall any specifics other than it was during sustained high rpm operation, that's all since I can barely remember last week ...

Your doing better than me...I cant even remember my first name half the time...

I had the same issue, misfiring at rotor 2. The problem was resolved after replacing the MAF sensor.

I've only gotten my 8 to deotante once, and it was rotor #2.
This is interesting. My guess would that rotor 2 is hotter than rotor 1, especially since the coolant flows 1-2. It would be a neat idea to try to make a T in the coolant feed hose and flow it into the rotor #2 housing. But the coolant flows internally from one housing to the other right? So you would have to block up the internal passage that connects them and make a feed/return circut for each housing. Could get complicated. But if coolant doesn't flow internally between the housings (which I think it does) it would be extremely easy mainly because each housing already has their own feed and return connctions, so all you need is a T fitting.

substained high rpm with partial throttle then full thottle will do it.
OD

We need lego housings!!!

[25 CHARACTER LIMIT SPAM]...............................[/25 CHARACTER LIMIT SPAM]

yup -- ive gotten "cylinder 2 mifires" always at high RPM spurts. Seems most of mine happened when I'd cruise at 90-100mph on the highway.

I got in mine pobaly too. And I don't know why, my car is now much slower than not a long time ago.. Misfires can be cause of that??

what model and what year is your car?

the rear rotor does run a bit hotter, because its cooled last. if you do a bit of searching on rx7 club howard coleman (among a couple of others) have egt and wb data of the fd's. they run a little leaner in the rear due to the intake design.

leaner + hotter = boom

since its there by design, its a tuning limitation, and being aware of it, is step one

fixes of course would be running the rear rotor a tad richer for the cooling, colder oil, colder coolant, etc etc

EU version, 231 HP , model 2004.

Really .... I do alot of high rpm shifts still no cel (not even pending)

Yikes ...

Now Im wondering what my engine will be like, when I tear it apart at around 60K miles ... (now 29.5, 30.5K miles to go !)

I was curious if anyone would bite on that idea I threw out there...

The coolant does flow internally from one housing to the next. I have thought the same as you. Block off the water passage - specifically in the intermediate plate - and do like a 45 degree bend (something not as radical as 90 degrees) leading out of the intermediate plate. At the same time, lead another line into the same intermediate plate for the second housing. Then reconnect down stream after the engine.

Or less invasive would be to run an auxillary water line and tap into the intermediate plate and get some cooler water into the second housing. But whether or not that would work I'm not sure. You'd probably have to run some pressure and temp sensors throughout the coolant system to have a clue.

Very true on the OEM or a turbo header, but I'd think you could get away with independant WBO2 sensors on a NA aftermarket tubular header as it would just mean inserting the new bungs up a few inches from the normal location in the collector.

http://www.japanparts.com/images/Ima...base=1&no=1762

...if anyone wants to give me about $2k, i'd gladly research it :lol2:

interestingly enough, it looks to me like the WBO2 sensor bung on the RE Anemiya header is actually in the rear rotor exhaust... not sure if that was for this reason or if its was just a packaging deal :Eyecrazy:

http://www.japanparts.com/images/Ima...base=1&no=3357

those are some damn sexy headers up there........

Anyways, I talked to MM about this more. He said what Mazda should have done is sprial the coolant passages around the housing. This is because in a rotary only one side is hot while the other two "areas" are realatively cool compartively. So if they sprialed the coolant passage after it went through the combustion area to either the intake or exhaust areas, then fresh colder coolant would be circulated to the rear rotor combustion area housing. This is of course wouldn't work for one of us to modify, but it's what Mazda should have done.

And the more I think about it, making a seperate coolant circut for the rear housing would be nearly impossible. Someone may be able to pull it off, but it won't be me.

It's an interesting delima we face now. Hopefully when Mazda comes out with a new Wankel they will sprial the coolant passages.

I'm not sure what real effect that would have. The coolant isn't going to lose an appreciable amount of heat until it exits the motor and reaches the radiator. It will pass some to the outer housing of the motor but not a large amount. Re-routing the coolant in the motor will only mean for a longer duration the hot coolant is in the block before "fresh" is brought in to replace it. And the big issue that was being looked at was that the rear rotor is recieving coolant that is already heat soaked. Therefore its ability to efficiently cool the rear rotor is severly compromised.

I would love to see water temps before entering the block compared to before and entering the rear housing and then upon exit of the block. i have a guess as to where the large spike in temperature is.

I get the rear rotor misfire code at every track event I go to. I can get it to happen at the same place on track, every time. I have tried a lot of things to get rid of the problem, with no luck. I only get the CEL on the track, and have not been able to make it happen on the street, even if I try to simulate conditions.

well you're sending the hottest coolant (combustion area passage way) to the coolest area of the motor, and the coolest coolant to the hottest area of the motor. That has to make a difference- I can't see why it wouldn't. Because it is right now, the same coolant is used to cool both combustion areas of both housings, so the coolant is already heak soaked prior to getting the #2 housing. By sprialing the passage ways, the hot coolant can dissapait some heat in the other areas of the engine and the colder coolant can absorb more in the combustion area.

You are just not going to lose much heat this way. Sure, I will give that the non combustion areas of the housing are not going to be as hot as the combustion area but they are still going to be hotter than the ~200* water temps. They are what make the water temps as hot as they are. I just cant see the water temperature spiking to - lets say for arguments sake - 240 when it passes the combustion area then - again for arguments sake - decreasing to 200 when passing the non combustion area. I can see the concept here but I just don't see it doing more than a couple degrees of good in terms of water temps to the rear rotor - if that.

You have to remember even after compression and combustion the hot exhaust gasses are swept further around the motor to the exhaust port. Its not like they are immediately moving out of the motor. So now you have a lot more area of the motor that is being heated to combustion chamber temps than you are accounting for. From looking at Charles Hill's plates I would estimate maybe only 1/3 of the housing is going to be appreciably cooler than that of the "combustion area".

To get the coolant in the rear rotor to be much cooler you somehow need to deliver fresh coolant. I have an idea in my head that I would like to try out when I get some free capitol.

^^ You are missing the point.
Its not about lowering the temperature of the coolant, its about NOT passing 240°F coolant over the combustion area.
If the coolant passage going by the #2 combustion area just came from the intake area of rotor #1, that coolant will be significantly cooler than what goes by there in the current configuration.

LEGOS!!!

Each housing has its own independant cooling, fuel, oil, intake, exhaust IN/OUT ports...

They then snap together via eccentric shaft!!

Brilliant!!

I AM an eccentric shaft!!!

:lol:

haha that's a good idea. I would worry about the structural integrity of the whole unit since the engine needs to function as a whole- also about the connection of the E-shaft.

But that is a cool thought- a 26B would be easy to make.

A single common water pump...just split off for more units...and increase size to compensate for them...

Same for oil...

Its fuel injected anyways...

spline in the front...receiver in the back...e-shaft secks

I have a question...since I think that may be the flashing CEL i had sunday...Would a misfire be followed by smoke from the exhaust? I had a friend behind me say there was quite a bit of smoke that came out from the exhaust.

and

What will mazda say if I bring it in?
________
RedMiledy

Well, since I suspect that the #2 rotor is running hot and lean, I'd think that it would be less carboned.
So, I dunno.

Perhaps! I didn't think of that.
I wish I had software that is sophisticated enough to log the individual injectors, rather than the groups as a single number.

I guess, when the AccessPort comes around, we will have answers to this sort of stuff.

That said, I don't think its likely that they do individual chamber control since they don't have any way of sensing the temp and A/F differential from #1 to #2 and Mazda's PCMs don't like controlling things that finely without feedback.

I stopped by service dept. at lunch, and he gave me the, I don't know that's hard to diagnose, must just be a misfire, it's nomral.

I am brining it in for some ther little problem next week, and will have them look into it more, but if I get anything useful out of this I will let yall know.
________
TylerHart

The Renesis is no different than any of the preceding rotary motors in this respect and nothing was done to address this issue with any of the 13b motors.
Anyway, this would mean running fairly rich in high-temp situations, which we know it doesn't (or running the front slightly lean, which I would hope it wouldn't).

I wouldn't count on it.
Obviously, RB did NOT succeed in breaking the PCM to any great depth or their re-flash would be considerably more capable.

must be other forces at work, I don't have this problem ...

Perhaps, or lack of particular forces in one scenario or another.

Its like the clicking clutch thing. I can get just about every RX-8 and Miata out there to click, even if their driver/owner cannot.

Just like I can get every chick out there off, even if thier driver/owner cannot.

I kid, I kid....

Ugh...

[[ This block of text is added to meet the 25 character minimum imposed by the forum. ]]
[[ Obviously, this does NOT deter users from posting uselessly short responses ]]
[[ and actually contributes to clutter and wasted bandwidth. ]]

A couple of points:
1.Not all 13B engines fail rear rotor,but based on a small personal sample it is 2 rear rotor to 1 front.
2 the oil circuit feeds the rear rotor first and oil removes about 30% of the the total waste heat,this mitigates to some extent the water circuit set up.

Thats some nice filler you got there...

Yeah, I noted that in my original post.
However, my contention is that with the relatively high flow rate of coolant compared to oil and its elevated relative ability to convey thermal information, the effect of the coolant movement is not negated by the oil.
Certainly, a quick look at the housings with an IR thermometer shows that something is going on.

from my personal experience, my first 2 engine replacements were all 2nd rotor misfires, symptoms include violent shake and clank sound at 45-55rpm
death on stoplight, etc etc

... just investigating on the misfire sound: did you hear that screaming sound like a fan belt slipping? i hear that misfiring (knock on wood) on the wankel is different than misfiring on piston motors

^tell you what, I'm glad you bumped this thread, as we have a years worth of knowledge now. Any updates, or perhaps a BHR solution?