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.