I have driven several Rx8's in the past several weeks while shopping around. All of the cars have smooth power output through 8500 RPMs. I just bought an '05 MT and have pushed it up to 8000 RPMs( still in the break in period). The power is smooth until 7000 RPMs where the power output has a slight but noticeable dropoff. This never happened on the other cars I was test driving. Any ideas?

 

different flash

 

Mine does that too - It's because the ECU makes the engine run SUPER rich up top...costs hp...plenty of HP.

 

I have also heard that the ECU makes the car run rich during the first several thousand miles of the car's life because it is breaking it in, I could be wrong but this might have something to do with it

 

Myne used to do this. But it definitly stopped! I'm not sure if its because I hit a certain number of miles and the ECU changed MAPS or because of one of the new ECU flashes I got. But it definitly got better. Myne now pulls all the way to 9k!

 

Thanks for the input, just freaked me out because of the strong pull to 9K on the other cars. I'll give it some time. Thanks

 

Was the car fully warmed up at the time? I believe that the ECU pulls back the power above 6500 RPMs if the car is not up to operating temperature. Anyone else remember this?

 

Yea, fully warmed up.

 

That is what mine is doing about 6300 though. I know because I put it on the dyno. It drops off and then starts to pick up a little at 7400. I think the secondarys are not opening.

 

could be flash could be ltft could be temp .... can be sure without some logginf of data

 

There are no codes for the aux ports not OPENING..

 

Listen very close during that power drop-off on the top-end. Is there also a slight knocking or rumbling sound that accompanies it? Part of the MSP04(N flash) campaign was supposed to deal with that issue. Thing is, I had my PCM re-flashed two months ago by my dealer after I heard that the N flash helps driveability. The car ran great but lately I am having the issue that the re-flash was supposed to cure. With the M flash I never had the problem. The problem is said by Mazda to be a lack of MOP volume above 6,000 rpm's which causes poor sealing and excessive blow-by. My performance issues and symptoms seem to fall in line with that diagnosis. My e.t.'s have gone from easy 13.7's to 14.0-14.1's and the e.t. reduction when using nitrous has gone from a full second to only .3-.4 seconds. Those symptoms indicate poor compression sealing. We'll see what the dealer's RX-8 specialist has to say on Monday. I thought I was the only one having this issue but I have discovered otherwise.

CRH

 

One good reason to keep the M flash

 

I have been wishing I never got the N after that recent backfire.

CRH

 

A little off topic, but somewhat related. Just got my 05.

Last week had some performance issues, thought it was flash related. Took it to the dealer and asked about the latest flash (P) in my car. They had my car for an hour, and the tech said I had the latest flash for the '05 model which is "D". Mazda apparently started flash numbering over for '05 and D is the latest. Kinda threw me as I thought I had M or N all along and needed a P. Incorrect.

So I guess the 250HP flash for the 05 will be E .

 

Overheard this also at the dyno run today as I was mildly disappointed in my top HP numbers. I attributed it to my car having only 2700 miles on it and a "tight" driveline contributing to excessive losses. But maybe this rich period is pre-programmed in and will expire at some predetermined mileage. Hmm... Certainly could explain better gas mileage later in life and better dyno runs on seasoned cars. We'll see. Not gonna get too hung up on the numbers though. I cant see myself EVER driving at 9000 rpm in 5th anywhere in the metro Atlanta area. And if you do "ooh, somebody stop me."

 

valpac and I were at the same Dynoday here in atlanta. My chart shows a 15 hp drop 7300 rpm's. The guys with the new flash on older cars, did not have this drop. I am going to try the new flash, since my car is older, and see if it helps. It seems to help the guys that have it already.

 

That 15 h.p. drop is right in-line with the three-tenths loss in my 1/4 mile times that I have measured. Do any of you with the "loss in power" issue also hear a strange noise on the intake side of the engine, kinda like a misfire or growling sound?

I had my car in the dealership today and took the RX-8 specialist out for a drive both dry and with the nitrous. Although he had a difficult time hearing what I was hearing, the car is still running like garbage. Since it idles and runs smooth we figure there is no seal damage but we cannot figure out why this thing is not pulling hard to 9,500 like it used to. I am getting no CEL except for the rear O2 sensor, which is normal because I have no cat. If I don't get this figured out soon I may give up and just pull the engine and go sick on it.

CRH

 

Charles,
Since you are willing to experiment, you might consider running a two-cycle oil premix ratio of 1 oz per gallon of gas. That has been reported as having a positive effect on sealing (RX7 site). You should use high octane gas with this because two-cycle oil premix does lower the effective octane. The engine will detonate on regular gas even without the added nitrous. Just a thought.

 

Shocar, I hate to always sound like I am one step ahead of everyone but I have been considering not pre-mixing (because the metering oil pump is supposed to handle the sealing at high RPM's) but, rather, trying stepping up to a higher viscosity oil. In reading the tech manual I discovered that in certain climes we are able to run thicker oils safely. I am thinking that with certain mods, and especially nitrous, some of us are approaching housing pressures that are a bit too much for mere 5W20 to seal properly. I'll re-read that CD manual a bit more in detail before I decide my next move. I appreciate your thoughts on the matter and having taken the time to mention it.

In the event that I decide to try the pre-mix route, which oils do you think would work best? I am familiar with all of them from my cycle-shop days. The Yamaha "R" oils were pretty reputable when I was last in the scene. Shows ya how long it's been, eh? Here in MI we have 93 octane routinely available and, in some places, 94 octane.

It seems to take about two days for the car to run its best after re-flashes/PCM clearings. Am I delusional, here?

Thanks again,
CRH

 

Charles,
TCW3 2-cycle oil should be used. This is an "ashless" oil. Valvoline is good. The premix will give a higher concentration of oil. You should notice that the engine idles diferently. Filling the tank near empty with say 5 gals of gas should allow you to try it out and then go ahead and add a full tank if you decide that the premix is not doing anything worthwhile. The 128:1 ratio of 1oz oil per gallon is a very concentrated mix. If the OMP is working at all, the full throttle OMP additional mix should have quite a bit of sealing oil available. And using heavier than 5W20 engine oil may be a pretty good thing to try too. Some people have tried RotellaT 5w40 oil with good results for the engine in general.

 

Rotella? Isn't that Shell's tractor-trailer line? I have decided to try the idea you have suggested and figure that if it works then I have proven my problem to be in the lubrication system. I will also try switching to a slightly heavier oil and see what that does, too. These are strictly Band-Aid ideas but at least I'll be able to make progress with this issue. Marietta 8 is reporting satisfaction with his P flash. I wish I could say the same.

CRH

 

5W-30 viscosity oil is Mazda's recommendation across the pond, which is what I've been using in my last few oil changes.

I like the approach you are taking here Charles. Might as well try this, however it appears those who have been dyno'd with the p flash have a drop-off happening at 7k.

 

In Europe Mazda recommends either 5W30 or 10W30 use. In all other markets they allow the use of a wide variety of oil grades ranging from straight 20, 30, and 40 weights to 10W30, 40, and 50, to even 15W40 and 50, and 20W40 and 50. Of course, 5W20 and 30 are also mentioned. If I had known sooner that our choices were so varied I may have used something other than 5W20 this whole time, especially when I was ragging my car Road Atlanta. I may try 15W50 next.

CRH

 

My car is now over the 1k mark and no longer has the drop off at around 7K RPM. Never heard anything from the engine when it was happening. Weird thing is now around 4K RPM it feels like it does the same thing. Since power doesn't start to crank up until I'm over 4K RPM it doesn't really bother me. Wished it didn't happen but not too annoying.

JH