I found vast differences in mine as well. The transition point from open to closed loop seemed to change...and this really effects what the A/F ratio will be in the upper RPM areas that are always open loop???? Never did figure out what was different.

 

brettus, yeah I am less concerned with the horse power numbers at this point then I am with the AF ratio. it seems to me that there are two defanite diferant runs. there are the runs with it loads up at 7,800 and there are the runs that do not. the only real odd ball (as far as AF ratios go) is the one that it loads up early on.

I was looking at some other members dyno sheets, and i have not seen anyone elses drop like that..... and like I said a couple post back, I think my butt dyno is broken as I never seem to notice any mod I do.

 

Glad you are not gunked up---check that one off! I would say coils is not the problem. My Ga group always saw higher readings on the 3nd to 4th pull(HP/torque) they didnt monitor a/f's.
Maybe you just blowed the soot out of her? Run a bottle or 2 of good injector cleaner through her(damn returnless systems can gunk at that dead end rail. Possible? Good advice on the maf.
Car hasnt dyno easily ever since Canzoomer 1st started. Team maybe right about the knock sensor also and Rotor IS right about the data collection.
olddragger
olddragger

 

Here's another thing to think about. If your car was cold when you did the first runs, your tires were too. Check the pressure in them before each run. The more runs you did, the hotter they got (to a point of course). Pressure goes up in them with heat. A tire with more pressure will have less rolling resistance. I run my tires a bit on the high side for gas mileage reasons and it works. At least on a Honda it does. That's one of the old tricks that people would use on dynos to get higher power numbers. They'd over pressure their tires and not say anything about it and their numbers would be a little bit higher than the guy who never worried about his tire pressure. It doesn't explain your a/f ratios though but at least check these before each pull the next time you dyno it.

I would also unscrew the knock sensor and wrap it up in a cloth and just tuck it out of the way. Keep it plugged in though. It's not a very good sensor and will actually false based on other noises it hears that aren't knock. Racing Beat does all of their dyno testing this way.

 

I am not seeing who suguested the CanScan, but that does seem like a pretty good idea. at least then I can see what is going on without going to the dyno everytime. for $129 it seems like a great idea.

I will try the injector cleaner as it is a cheap test. but I would think it would be runining lean if they were pluged up???

 

I e mailed CANScan today after I baught it and asked him what he thoguht.


From me:
Hello, My name is Casey, I just ordered the CANScan with the RX-8 software. I am just wondering if you think the CANScan will help me figure out what is going on with my air fuel ratios. I had my car dynod the other day and attached I have included the results of the air fuel. As you can tell 3 of the 9 runs were fine (and produced 201 h.p.) but the other 6 runs loaded up at 7,800 RPMs (and produced a maximum of 184 h.p.)

Anyways, my main question is do you feel this might help me figure the problem out? Have any suggestions to try first? I was thinking maybe O2 sensor, or injectors that are opening up when they shouldn't be.

Also shouldn't the air fuel be more around 13.6 : 1 or does the RX-8 run more rich then most cars?

Anyways, thanks for any help you can give. I look forward to receiving my new CANScan!

~ Casey Brier


From him:
Casey

First, the O2 sensors are not used under full throttle operation. The Mazda PCM has a built in fuel map it uses for those conditions. It takes in speed, gear, air temp, throttle position, and mass air flow to determine the fuel injector pulse width for it's calculated AFR. At full throttle under load the AFR will drop below 12, maybe down to 10.8 or so. In my opinion, I think the PCM retarded the timing during those bad runs. You can check that out by data logging the ignition timing during the runs and then compare the logs to each other. The RX8 has a knock sensor and if pinging is detected, the timing will be retarded until the pinging stops. This is only my opinion, hope it helps and feel free to contact me any time.

Best Regards

Dan Harrison

Harrison R&D





nice that I have something to start with. I didnt even think (or know) about the O2 not being a determining factor at WOT. I think you guys are on to something with the knock sensor. you guys think the insane loud K&N might be setting it off? I heard these are very sensative???

 

LOL, imagine that ...

 

???

 

This sounds very interesting about the knock sensor! I will unscrew it next time i'm on my RotoTest.

/Lasse

 

Speed --what Team was communicating--I believe was it has been know by more than a few that the 8's knock sensor is a fickle beast. Racing Beat detachs the knock sensor from the engine and wraps it in some soft material, when they dyno.(you have to leave the sensor plugged in).
Harrison is speaking of the car running in the open loop mode. It does that without the o2 sensors. I forget what rpm the car goes into open loop.
I wonder why the knock sensor would read something at such a high rpm when engines are suppose to be more detination prone at lower rpm?
Never drive the car without the knock sensor in place. Dyno --ok take your chances---drive--never.
olddragger

 

.

 

be interesting to see the canscan data.
I wonder how hot the engine was getting also.
OD

 

I know team... you called it... you da man. ( I see what you mean now by "imagine that" )

 

I switched over to 0W30 Series 2000 Amsoil, several weeks ago (had been thinking about it previously), from 5W30 XL Amsoil and immediately noticed a difference I didn't want to say anything till I had ran it for a while to see if anything changed. It has kept the same good feel.

It is like the car is running during the summer, only better.

And this was with well below zero temps (think it was -17 F when I pulled the car out of the garage).

Since then the temps have come up to 37 degrees F. The car still feels like it doesn't have to work as hard to start as the Amsoil 5W30, and it has more power.

 

dang it gets cold where you live! Move on down to Ga!
olddragger

 

Then I would have to deal with the lovely humidity.

 

Where exactly is the knock sensor located?

 

in a spot you shouldn't be messing with ...

 

Ha--unless you are racing beat with the engine on the stand
OD

 

What kind of answer is that? I doubt the place my car will be dynoed is aware of where the knock sensor is on a rotary. Thanks for the help though. ********.

 

As sad as this may seem...

Team is actually annoying AND useful...dont mind his oscar the groutch persona...youd be pissed all the time too if you were born with that paperbag...Haa...

 

that said his answer was correct..

beers

 

Guess I should have told him to SEARCH instead

as sad as it may seem. the Twinkster isn't even useful