Derex'8

iTrader: (4)

Is that - or + trims?? Just wondering because I'm using the same intake and was getting - trims

Flashwing

In my case I'm getting + trims because my AFR's are rather lean. My problem is some elements of the tuning process are the opposite of what they appear to be.

Some of the issues I am working with is I have slightly smaller injectors than the factory OEM rating.

My hope is to get my MAF calibrations nailed down, properly scale my injectors and then start with a rich N/A tune and go from there.

Charles R. Hill

iTrader: (7)

Why is that?

Flashwing

Well, let me re-phrase that previous statement. When I say I have smaller injectors I mean that the fuel delivery rate of my injectors varies slightly from what the factory specs should be. I'm running the oem injectors which are 290/380/380 respectivly.

Speaking to Jeff through my tuning process we both came to the conclusion that my injectors might produce slightly less fuel and that the factory tolerances allow a +/- 5% in fuel delivery. I could be more at a 280 or as high as a 315cc on the primary injectors for example.

After doing a lot of reading I think I am going to go back to the Mazda stock map and start there. I used the Stage 1 map from COBB and I've ran stupid lean the entire time. Though honestly I think I might have something else going on because using the MazdaManiac tune I've also been running lean so there might be another factor at play.

The end result in my eyes is to get the injectors and MAF calibrated properly so I can get proper air/fuel adjustment. I'm trying to make sure I understand how each of these elements work before moving onto something else. My only real gripe is that I won't be able to calibrate the entire MAF curve easily unless I booked some dyno time at UMS and used their load bearing dyno.

More experimenting tomorrow!

Edit:

One question for everyone. Is the thermostat on the RX8 controlled by the ECT temperature or does the thermostat have it's own means of obtaining temperature readouts? There's been a long time battle regarding the accuracy of my water temp gauge and I have reason to believe my ECT is about +10 degrees from actual. I know you can calibrate your ECT in the accessTuner software.

rotarenvy

one thing you should be wary of is you MAF might not be out. you may be trying to calibrate the smaller injector volume out by tuning the MAF. how do you tell if it the injectors or the MAF?

Flashwing

Mazdamaniac had made the suggestion the injectors might be slightly smaller than oem based on what we were seeing during a dyno session last August. Off the top of my head I cannot remember what the factor was which drew him to that conclusion but I recall agreeing with him when it was explained.

I agree that it's very possible my MAF calibration is more to make up for the injectors rather than the MAF itself being off. I'm using the AEM intake which is molded to the exact specs of the stock intake tube. In theory, the stock trims should work fine.

On the other hand I have to go over the car because since it's cooled off I've been seeing spikes in my trims so who knows what is going on.

rotarenvy

isn't that what it's supposed to do? a change in temp from summer conditions to winter would give a +trim due to the colder denser air. if your resetting the PCM regularly then it's probably just trying to compensate.

if I was you and were really concerned about zeroing the trims then I would eliminate the number of variables. get the injectors cleaned and flow matched so you know they aren't causing the variation then you can worry about your MAF scaling and know your not wasting time trying to calibrate it.

Flashwing

Thanks for the advice. I will look into it.

My thoughts exactly regarding the trims. Seeing as this tune was done when intake air temps would be between 80 - 100 degrees and now my intake air temps are between 60 - 75 degrees I'm sure the colder air is causing the car to run a bit lean.

r0tor

iTrader: (1)

the fuel trims will not change significantly with temperature. Its a Mass Airflow Sensor which measures Mass and Mass is not temperature dependant.

There is more to a MAF calibration the the overall diameter. The MAF only measures the mass flowing through a small portion of the pipe and makes assumptions that the flow is fully developed and laminar. If there are any bends, ledges, or obstructions it can change the flow profile and therefore the calibration.

The easiest way to check if your MAF is in the right ballpark is by looking at your % LOAD at WOT. The RENESIS is suppose to have a 95-105% intake efficiency... so your LOAD readings at WOT should pretty much match.

WhiteSnowflake8

iTrader: (5)

I just bought a COBB from VividRacing since i get some discounts. and im getting an agency power full exhaust this weekend and was wondering if someone could pass me a nice map. please!! lol
Thanks

rotarenvy

can you explain how temperature doesn't affect a gasses mass and mass-flow then? answerer because the sensor reacts to density in a pipe not mass-flow.

there are still temperature and pressure compensations that occur in the PCM

MazdaManiac

iTrader: (3)

Nope. Go back and look again.
I tweak the entire curve by hand.


lol

Never scale the entire MAF curve above 10%

05rex8

iTrader: (7)

^^this is why I let MM do these maps.....

toneskii707

???? Should of went through MM

zoom44

you have a container with 20 molecules of "air" in it.

Lower the containers temp by 10 degrees. How many molecules of "air" are now in the container?

Now raise the containers temp by 20 degrees. How many molecules of "air" are there in the container?

Flashwing

This is the method which makes the most sense to me. Since there are various other changes that occur across the load range having a single multiple for the whole curve won't fix the problem...just one area.

I'll need to log my STFT and LTFT across the load range and then tweak various sections.

[/quote]

Ah, so scaling it by 16% probably would be a bad idea.

My specific map has several hours of street tuning as well as dyno tuning involved. I'm pretty much trying to re-invent the wheel but that's the only way I'll learn how to do this stuff. It will take me a lot of time to duplicate the standard map I've been using.

rotarenvy

I don't see your point zoom44. but I'll play anyway:

the same number but you have just increased the pressure if the container isn't a balloon. however since this example is a closed system and not an open MAF pipe it is a poor analogy and doesn't describe why a MAF pipe works regardless of temp.

Flashwing

The MAF does take intake air temperature into account and makes adjustments to the current calculated load. Since density of air increases as temperature decreases this changes the VE of the motor and therefore changes the real calculated load values.

Intake air temps do change the nature of air flow because it's a product of mass/volume and in this cause would be grams per cubic centimeter. The lower the temperature the greater the density so the more mass you pack into the same space.

The intake air temps as detected by the MAF will adjust your load slightly.

Hope that makes sense...I think I just scared myself.

r0tor

iTrader: (1)

is that really a challenge?

r0tor

iTrader: (1)

Mass Airflow Sensors measure the mass of the air moving past it. Please search the thousands of sites out there that explain this.

The mass air flow gets converted to an engine load (actual air flow / theoretical airflow at that rpm). The theoretical airflow is adjusted for temperature and ambient pressure.

Flashwing

Well unless anyone has reverse engineered any of MazdaManiac's tunes I guess it's his word against everyone elses....

r0tor

iTrader: (1)

...only can be done with expressed written consent of course...

rotarenvy

I did search and edited my post with the answer.

however you say in the post above that temp doesn't effect the tune but here your saying it does effect the tune not the MAF.

I was wrong about how temp effects the maf however it can still alter the tune.

rotary.enthusiast

Fuel trims are caused by the reading on the front O2 sensor differing from what the car expects to be running at in the current conditions. There are lots of things other than an inaccurate MAF reading that can cause this. Ask yourself if you really want to "fix" fuel trims by changing the MAF reading without actually knowing if the MAF reading was inaccurate or not in the first place.

Flashwing

I understand that there will never be a situation where my trims are going to be zero all the time or even near zero. + or - 5% would be very ideal but currently I've been seeing +15% which in my opinion is a little much.

While the MAF itself might not be the source of the trims it's one way to bring the car correct. The whole point of making sure the MAF is calibrated is so I can input fuel table values and not have to make adjustments cause the trims are extreme one way or another.