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How to Scale your MAF for Flash Tuning (Cobb, Hymee)

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How to Scale your MAF for Flash Tuning (Cobb, Hymee)

Old 04-18-2009, 12:08 AM
  #101  
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I think Morks was hinting I need to get off my butt and build a piece of software to add to Baseline.
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Old 04-18-2009, 10:00 AM
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Originally Posted by r0tor View Post
This point can not be stressed enough as my research found a varying amount of lag in the AFR reading
That lag could be OBDII port reading rates. Too bad you can't interface the Innovate LC-1 into the AP (or vice versa).
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Old 04-18-2009, 10:51 AM
  #103  
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You can. But I cant get my ATR to talk to my car through the dongle. It might be a computer issue and not an ATR issue. BUt in the ATR there are communication options for what looks to be popular wbo2.
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Old 04-19-2009, 04:13 AM
  #104  
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Cool... so I got my logs taken in open loop (~4250RPM) with cobb's stock map. I took a few MAF voltage/flow readings the with good sets of data for averaging. I am using an accessport to change the calibration here, so I wanted to double check this is OK before flashing.

My lambda value for 2.11V is 0.07% off. I did another one for 2.40V, and that was also 0.07%. Next around 7800RPM, 0.09% at 3.07V. Can I safely scale the entire MAF by 0.07%? or am I close enough as is and shouldn't bother with it. Is this premature without more data?

Last edited by jujo; 04-19-2009 at 04:21 AM.
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Old 04-19-2009, 07:15 AM
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Originally Posted by carbonRX8 View Post
You can. But I cant get my ATR to talk to my car through the dongle. It might be a computer issue and not an ATR issue. BUt in the ATR there are communication options for what looks to be popular wbo2.
So the Accessport has a 0-5V analog input for aftermarket wbo2?
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Old 04-19-2009, 02:10 PM
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Originally Posted by shadow1 View Post
So the Accessport has a 0-5V analog input for aftermarket wbo2?
i believe if you run the ATR software on a laptop and plug an WBO2 sensor into your laptop, Cobb has some drivers available so you can access the WBO2 data from the ATR software
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Old 04-19-2009, 02:48 PM
  #107  
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Originally Posted by jujo View Post
Cool... so I got my logs taken in open loop (~4250RPM) with cobb's stock map. I took a few MAF voltage/flow readings the with good sets of data for averaging. I am using an accessport to change the calibration here, so I wanted to double check this is OK before flashing.

My lambda value for 2.11V is 0.07% off. I did another one for 2.40V, and that was also 0.07%. Next around 7800RPM, 0.09% at 3.07V. Can I safely scale the entire MAF by 0.07%? or am I close enough as is and shouldn't bother with it. Is this premature without more data?
Honestly at .07% I wouldn't even worry about it - that means you multiply your voltage by .0007... not a very big change - BUT if you want to do it just to see if you can get closer - have at it!
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Old 04-19-2009, 05:16 PM
  #108  
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Originally Posted by Kane View Post
Honestly at .07% I wouldn't even worry about it - that means you multiply your voltage by .0007... not a very big change - BUT if you want to do it just to see if you can get closer - have at it!
Thanks Kane. I decided I'm not going to touch it...yet. Started the procedure for MM's tuning today, so going to follow through with that. But once that's through I'll be having at it :D and perhaps by then Baseline with MAF will be out. It will be interesting to compare. This is all new to me...
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Old 04-20-2009, 01:05 AM
  #109  
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Originally Posted by Kane View Post
Honestly at .07% I wouldn't even worry about it - that means you multiply your voltage by .0007... not a very big change - BUT if you want to do it just to see if you can get closer - have at it!

I am wondering if he means .07% or 7%. There is no way that you would fretting about 7 parts in ten thousand. Seven in one hundred is a different issue.

PLUS if you are 7% too high is a completely different animal than if you are 7% too low. One of them could put a hurt on you where the other would "only" make you run too rich.
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Old 04-20-2009, 01:19 AM
  #110  
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Originally Posted by carbonRX8 View Post
I am wondering if he means .07% or 7%. There is no way that you would fretting about 7 parts in ten thousand. Seven in one hundred is a different issue.

PLUS if you are 7% too high is a completely different animal than if you are 7% too low. One of them could put a hurt on you where the other would "only" make you run too rich.
Well, it seemed odd to me it was that close to the curve, 0.07% off...
Strikes me as odd because I have an aftermarket intake.
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Old 04-20-2009, 02:16 AM
  #111  
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Originally Posted by jujo View Post
Well, it seemed odd to me it was that close to the curve, 0.07% off...
Strikes me as odd because I have an aftermarket intake.
Not really - small engineering tolerances could account for it.
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Old 05-05-2009, 05:36 PM
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This is serious info here.. thanks Kane...
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Old 05-07-2009, 12:46 AM
  #113  
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Anytime man.
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Old 06-25-2009, 11:32 AM
  #114  
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Ok. I finally got my car running again. I took the downtime as opportunity to do some more editing. So the new ride has a "custom" front crash-bar, K40 and Blinder (using the unused fog light switch as the on/off switch; way cool), new a-pillar gauge pods, LMA3, fuel pressure gauge, Mazdaspeed intake modified to fit the greddy tubing and 650cc/min in bank two.

I also rescaled my injectors in the AP (a guess) and edited the injector latency (based on injector-rehab info). Then I started collecting data to scale my maf.

The issue is that, for some UNKNOWN REASON, while in 3/4 gear, at around a load of 45, at RPMs around 4500, the AFRs will either run at the appropriate AFR or they will drop to super-rich.

Let me restate this. While at steady state in OL at load of 45 and RPM of 4500 where the expected AFRs are just south of stoich, the measured AFRs can be one of two values, either close to expected or WAY too rich.

For the life of me, I cannot figure what tables are interacting to cause this and I need to figure it out prior to scaling the maf completely. I have only two hypotheses. One that it is an injector issue, that one pair of my bank two's are flowing more than the others and they are randomly turning on and adding too much fuel. The other is related to the observation that it seems that if the RPMS are trending upward, then I see the richness. Are there hidden tables that measure rate of RPM change? My accelerator pump tables are set to 1 in the range that I am having the issue.

THoughtful responces are appretiated.
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Old 06-25-2009, 12:43 PM
  #115  
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Interesting... did you try to scale your injector bank 2&3 latency and see how that affects it?

It seems like the latency may be screwing with you - - as soon as it hits some magic load area you have more latency calculated than you need.

Last edited by Kane; 06-25-2009 at 12:52 PM.
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Old 06-26-2009, 09:11 PM
  #116  
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I wouldnt think so. The lateny table has baro and voltage as independents and microseconds as dependents. At least in that table, latency is not a function of load or RPM.

Here is my best 2d display of the data. I will note again that this is OL (LTFT=STFT=0). I have also filtered this data farther to insure that I was in 3rd or 4th gear (using speed/rpm), to insure I was above 3000rpm and to limit loads seen on the graph. The x-axis is a very narrow representation of availible load. This bifurication is the ONLY "split" that can be seen from low load to well over 1. I am not having any current issues where my measured AFRs are significantly different from commanded (tho I will admit that something might turn up.)



You can see two populations of AFR at nearly identical load and RPM. It shouldnt be this way unless there is another interaction. I ran several tests for interaction across many variables, including rpm delta and saw very little to suggest an issue.

My current hypothesis, as I said, is that one pair of my bank two (P2 and Sec) injectors are not scaled appropriately and that right around this load the injectors occasionally kick-in. But beside this, I am at a loss. Will need to do some more logging.

In the interests of full disclosure, the graph does not represent the dependence on time. I will say that, over time, if the AFRs are high, they will remain high and if they are low, they will remain low. The data does NOT jump between those populations randomly.
Attached Thumbnails How to Scale your MAF for Flash Tuning (Cobb, Hymee)-bifurication.jpg  
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Old 06-26-2009, 09:48 PM
  #117  
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I love that analysis. That is really good stuff.

Cheers,
Hymee.
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Old 06-26-2009, 09:50 PM
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i'm guessing it's something at the quantum level.

get it? since your values are both rich and lean?

yuk yuk.

but seriously, that's about when your vfad is supposed to open, isn't it? maybe something is weird with that. or maybe the coolant temp has something to do with it. I really have no idea though.
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Old 06-26-2009, 10:54 PM
  #119  
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Originally Posted by myriadshalaks View Post
i'm guessing it's something at the quantum level.

get it? since your values are both rich and lean?
Actually, you might be more correct than you think. The effects observed at very small scales such that things can appear to move between states without having any values between is caused by the probabilities that follow wavelike or harmonic behavours.

Given that I just put in a new intake (Mazdaspeed) that is rigged very differently than it was designed did suggest to me that perhaps a standing wave is being setup somewhere ahead of the MAF sensor and that this wave randomly "breaks" at different flows. The MAF might then see appropriately bifuricated flows in these ranges of load or some other behavour that could be a observed. I have not really looked into this as it is unlikely given that while the intake is setup quite different than it was intended, the flow is very straight for nearly two feet ahead of the MAF sensor and there is a screen in the flow. If I cant pin something else down, I might start sifting through the data for this.

As for a valve opening, it is possible, but still more likely that it is "user error" in the ATR and can be "tuned out."

Thanks for the thoughts.
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Old 06-27-2009, 01:43 AM
  #120  
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you said LTFT = 0 and STFT = 0 as well . OR did you mean LTFT + STFT = 0 ?
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Old 06-27-2009, 08:02 AM
  #121  
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Originally Posted by Brettus View Post
you said LTFT = 0 and STFT = 0 as well . OR did you mean LTFT + STFT = 0 ?
Well, I used to just use LTFT-STFT=0 as my filter, but have started using LTFT=0=STFT as this weeds out some deceleration and other datapoints.

I should note that these data were collected by direct connection to the computer. When you datalog via AP, the zero value is 0.16 or something like that. LTFT=0=STFT is never true when logging via AP, IIRC.
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Old 06-27-2009, 11:04 AM
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Carbon, do you know when the load transition is between the 2 injector banks? I suspect you are correct about the AFR change resulting from an injector issue. I really doubt the intake will cause this.
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Old 06-27-2009, 11:27 AM
  #123  
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Yeah me too - I am voting injector issue.
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Old 07-01-2009, 10:03 AM
  #124  
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Interestingly, this issue did NOT turn out to be related to the injector scaling; however, I have learned somewhat about the effect on AFR as a function of the injector scaling and believe my bank two injectors are not scaled perfectly.

Honestly, I am not completely sure EXACTLY what caused the above issue, but an inappropriately scaled MAF calibration and a poorly designed fuel map were contributers.

Just to sum up: I got my car running with new injectors and a MS intake. I recalibrated the MAF to stock assuming that because the MS intake is the same size as stock (or close) and as it is installed by the dealer without a reflash, that a new calibration is unnecessary.

I did that and the car was fast! The issue was that I was not hitting my target AFRs and wanted to start a little rich. I logged data, analyzed as above and recalibrated (keeping the stock calibration from 2-20g/sec airflow.) This got me much richer, but with the above result and lots of bog.

I concommitantly had some idle issues with LTFT in the +15 range. I shrank my primaries, and resolved that issue. This had essentally no effect on the issue at cruise.

I then played with the scaling of my secondaries. While I could get richer or leaner with this alteration, the AFRs were still out of line. Some where along here I noticed that my OL fuel maps were very ugly and jumpy. I dont know where this came from. Perhaps an old map? I re-adjusted a map that I believe is a work of art.

At this point I realized that my MAF calibration was just silly. I dont know how I came to this realization, but I reverted to stock MAF calibration AGAIN with results that were promising but not great. I datalogged again, re calibrated by fitting then datalogged AGAIN, recalibrated with fitting and with fine tuning by hand and will datalog again today to see the results.

Again, I am not absolutely sure of what I changed besides the primary scaling (secondaries are back to my first estimate) and some fine tuning of the MAF calibration.

The interesting thing is that with my greddy intake, I obviously had greater turbulance as I observed much greater "noise" in my datalogged air flows, but using a non-linear fit to produce the maf curve was sufficient for a good tune, but now, with the MS intake, the noise is much less and I observe much finer "ripples" in the maf calibration curve.

I am guessing, and will experiment later, that these ripples are a result of mis-scaled bank two injectors. I say this because the ripples occur right around where I have observed the changes in AFR with secondary injectors scaling. The ripples look like what I would think would happen as the different injectors come on line.

The good thing is that if this is true, this will provide the final "equation" so that there is a way to scale your secondary and P2 injectors correctly separate from the MAF calibration (basically, if you have 3 varibles to solve, you need 3 equations. If you have 3 varibles and 2 equations, you can only solve to a function of at least 2 of the varibles.) Essentally, if the MAF calibration is smooth at the injector transitions, then your injectors are scaled correctly. Again, this is my hypothesis.

Be that as it may, it might not matter. It seems that a wobbly maf curve makes up for deficiencies in the injector scaling. Maybe.
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Old 07-01-2009, 10:09 AM
  #125  
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P.S. All this above also means that if you change your injector scaling, you MUST recalibrate the MAF immediately following. Period.

Scaling your injectors requires two flashes. One to scale, (datalog) one to recali the MAF.
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