I don't understand why you wouldn't try it with and without the fuse during the hour you have the dyno?

I think this is the chart people were mentioning earlier.

This was on Kristopher_D's car. He did a couple of runs on the dyno. Then we pulled the fuse and this is what we got. I guess his LTFTs were enriching his ARF and when we pulled it it leaned out somewhat.:dunno: I suppose if you have heavy LTFT numbers you could see some interesting changes but if they're small you won't see much of a difference.
http://i164.photobucket.com/albums/u...otivatfuse.jpg

7 HP is meaningless.

because I am afraid that I might run out of time.

Ahh but I guess you're right, I can try to do everything in the same hour.

Will see what happens.

7 h.p. isn't meaningless if it is repeatable while the vehicle stays strapped down.

Just pulling the fuse is not going to reset the LTFT/STFT. He would have had to pull the battery ground also.

Ok, I see what the problem is. I thought we were talking about the DSC fuse but actually we are talking about the ROM fuse. I was wrong, pulling the ROM fuse will reset the LTFT/STFT.

I agree, Ray. I am too lazy also. I just use my computer to reset everything...

No it isn't.;)

are you kidding me? thats less than the 238 to 232 crank quoted spec at the last change. how much time have i spent going on about the 5% rule? if everyone had dyno'd with no trims they may not have had to make that change. so to me thats allot.

7 HP isn't 5%, its about 3%.

I guess for advertising its a lot.

238 to 232 is 6 hp. but they had to change the advertising because 238 was not within the 5% margin of error allowed while 232 is

ahhh that explains a lot .
I would pay for 7 extra hp if I could get it - already have the underdrive pulley though so don't know what else to do ..... heh

Well Alot is subjective but not meaningless. a mole of oxygen molecules may not be "alot" but a mole of volkswagen microbuses would be "alot."

VW MicroBus FTW!
http://www.youtube.com/swf/l.swf?vid...FiXCRsJi4M_8u&

MM, 7 HP may not be a lot to you... but to us that dynoed at 170 WHP it is 4.12%. Equal to about a thousand dollars worth of mods.

I am sure that 7HP is about 2% or less to you.

Us NA guys need all the help we can get!

pull the abs fuse prior to a dyno - OK.

But with the advent of the accessport... we can easily 'reset ecu' to clear trims without having to pull the ROOM fuse.. or am I wrong?

Sure. But with the Accessport you should be able to have your car tuned properly so you don't have to. :)

right, I hope to dyno my car soon so I have a good 'BEFORE' dyno..

then when Jeff finishes working his magic on my calibration I intend to go back for an 'AFTER' dyno.. probably with a nitrous run somewhere in there.. ;)

Well, the idea is that the last pull when I work on your tune is the "after" dyno.

I don't pull and fuses or anything like that. I just kill the traction control the normal way.

note to self -- reset my ECU before I drive my car every morning.

c'mon people. really, we've gone from disabling dsc/abs to reseting the ecu to clear all fuel trims prior to a dyno run... something that happens by attrition every time someone with an AP flashes a new map.

A 7 to 8 HP increase may be meaningful on a cute line chart but if you lose it once your ECU has had a chance to relearn all of its trims what is the value of it?

If anything we should subtracting 7hp from our dyno runs... at least those where we use an AP and flash between runs or for some reason that completely defies all logic pull the room fuse beforehand.

Thanks for the resurrection alz0rz although I don't think I've learned anything beyond the fact that everyone is trying to cheat on their dyno sheets.

That doesn't make sense. With a good AP tune you shouldn't see any change from pulling the fuse because the car is no longer trying to detune itself for cat life protection.

^^ Not exactly. But there are things the car tries to do to itself over the course of the many drive-cycles that are designed to pull the engine into compliance with its pre-existing fuel maps.
It is rather clumsy at it and it doesn't really have any way to know that the tuning deficiencies are the product of more than one possible miscalculation on the part of Mazda's drivetrain engineers.

The "CAT preservation" scheme is a broad misnomer that we (I) am guilty of overusing.
In its purest form, the "CAT-preservation" tuning is rather benign. Its supposed to only be about 1 point of AFR richer than stoich.
But, because of mis-sized injectors and mis-calibrated MAFs, it can be several points rich or even a point lean.
The intentional error on the part of Mazda's tuning efforts is designed to eliminate the possibility of it being several points lean.

So correctly calibrating the PCM for the actual injector sizes and actual MAF voltage for a given airflow with the AP will also reduce this gap?

Now all we need is 1 O2 sensor per rotor and the ability to adjust injector pulse width and timing per rotor and we're golden. :)

Yes. That is what my whole new set of calibrations and the new procedure are directed at.
Once those baseline changes are accounted for, the tuning becomes merely a function of inserting a desired set of new values in the fuel and spark tables.

An excruciating amount of time was spent (by me) "chasing the tail" of mis-adjusted injector scaling and MAF calibration.

sounds a lot like Manufacturing. You can't cut something on a CNC machine until you can tell it exactly where it is in the fixture and where exactly the fixture is in the machine. Otherwise you're just guessing about what the actual dimensions of the finished part will be.

All about finding out where something is in reality relative to "zero." :)

Yes - Finding "zero" is what this does.

I was always having to infer zero from the end results before, which is kind of like inferring the end of a book by the way the ink distorts the shape of the back cover.

wow, what an analogy. that explains a lot of the storyline with the AP tuning, which btw i'm glad you got things streamlined. see people, even MM learns as he goes sometimes. he isn't an evil artificial alien lifeform..... or is he:eyetwitch


back OT:

I've read bit and pieces of this thread and other dicussions about it dozens of times over the last couple of years. STILL the more i read, the more go in circles. In my mind i know i should be able to hop on a dyno, fully disable TCS/DSC and go at it. But at the same time i cant seem to accept it blindly like that. Maybe it's a lack of full understanding of what the PCM does in regards to torque sensors, traction, and wheel speed... is there a chance that anyone can really fully break it down? Any sections of any manuals that cover the flow/logic diagram or whatever the PCM uses? I have most of them afaik but i havent seen anything obviously related in my quick skimming...

Jeff, sorry - i don't intend to be asking you to step up and educate, but honestly i dont know who might know the in's and out's of the way the damn thing works as well as you

The two times I have put my car on a dyno I have simply turned off the DSC completely and it worked fine on both a 2 wheel and 4 wheel dyno. Dynojet and Mustang dyno.

No timing pulled and no weirdness from the PCM. Just do it.:lol2:

Go ahead and dyno it.

Dam I wish I found this thread before I dynoed my 8 lol back to the dyno

Upon dynoing my car - we received consistent hp numbers of less than 1 hp difference and all we did was hold down d.s.c. for the few seconds

as a matter of fact i had mentioned this thread to my tuner and he was curious, as was i, to find out if it is true, we looked through the rx8 dealer manual and find no tie to the abs cutting engine power - and as previously stated, numbers were consistent and no 'power loss' was evident.
_

my $.02

Street Driving with DSC/ABS fuse pulled = ?

this thread is bogus and doesn't deserve sticky status, I never did anything special for dynoing my car

/\ lol maybe not for your car but for mine it is. 164whp in all honesty sucks ass. Maybe my coils are finished...

well I have an 04 RX8 and have no DSC button and when I dynoed my 8 it was pathetic and on top of it all it was at a honda shop. My fuel was WAY rich my numbers didnt break 135hp and every light imaginable light up my dashboard like a christmas tree then once I pulled it off the dyno and drove it those lights went off. Then proceded to race and beat a car that dynoed before I did that showed 173hp on the same dyno. And I didnt pull the fuse either. So I will go back to this same shop pull the fuse and see what I get.

So I guess this never happened.

bump for the most tarded thread on the forum, except for maybe the aggressive wheel thread ...

Yeah, I can't believe we are still having this discussion.

If anyone doubts that there is NOTHING special needed to dyno the RX-8, watch the live video feed from the SoCal dyno day on the 27th and 28th of March.

or just be there and watch it in person

Even mo bettah.

Though, I suspect people will be sitting in your car watching "Blade Runner" or something....

We aren't . It's just that Team keeps posting in here .
But he does have a point ,the thread should be de-stickyed (if that is a word)

Something I have found with dynoing mine that might be useful :
Be carefull that there is sufficient airflow to the radiator . The guy that does mine insists on directing the fan into the intercooler and i have seen engine temps go awhol as a result .

That's because most dyno fans are woefully insufficient

Were, anyway.
A lot of the dyno operators are moving up to two or three of those high-velocity carpet-drying turbines.

:hahano:

for the 8 there should be one main fan directed at the radiator and perhaps 1-2 smaller ones at the oil coolers .
Next time i go for a big whp dyno I'll hire an extra fan to do the 2nd radiator

I guess it depends on the fans.
The carpet fans (usually just two pointed in the "mouth" at the IC and rad) they use at UMS here in Tempe actually over-cool the car if I'm not careful.
Its not unusual to see my coolant temps drop below the 175°F threshold between runs if I don't run them close enough together.
Oil temps simply wont go over 185°F or so no matter what.

"Oil temps simply wont go over 185°F or so no matter what. "

Good to know




The other issue is that dyno operators don't realise how hot our engines get before the gauge moves .

Yes I am going here, but no; I am not discussing "it".

Two and a half years and no one has managed to do just this? What ever happened to the Scientific Method? Leave the philosophical arguments out of this and just prove whether or not there is a difference between the two with results.

Unless someone has actually done this (and pending $150 I can rationalize throwing away), I will step up to the task sometime this year. My car is -- with respect to the "major horsepower upgrades" section -- very much unmodified; so I hope this isn't a worthless gesture for the sake of those using aftermarket systems. I have a Hymee sCANalyzer; would any data logging be useful for such a comparative test, or would the dyno sheet prove to be the only interesting bits of data?

So no absolute truth or difference in pressing the DSC button when dynoing... yes?

Un-sticky then....