MAF Scaling - Open/Closed Loop Fueling info

[Dru670]

can anyone post screen shots of their mean and mode graph on the MAF scaling app?

[dave-]

Have an idle dipping/desire to stall on light throttle application after installing bigger injectors (ID850's). Car is turbo'd but didn't do it on stock injectors. At the time we'd loaded the SBD OFT map and just did some basic fuel and timing edits at WOT on the dyno to verify the turbo install was ok.

MAF is mounted just before throttle body and BOV is recirculating. There aren't any vacuum leaks that we can find. Not sure if MAF scale will fix it but I'm sure the hardware changes would benefit from a rescale. Would have been much easier to re-scale prior to putting the injectors in but bit late for that now.

But first post quotes jamesm saying something to this effect is possible with altered fuelling components and needing to isolate DI/PI for rescaling? Else where in the thread he goes onto say:

My process is this: disable port injection. scale maf to center mass against the DI only (process separation). switch to 100% port... adjust port scaler/latency against the now-known-good MAF. recombine and fine-tune in the MAF scale.


But you can't just go 100% DI and then head out doing WOT runs to obtain logs and if you're only logging closed loop, surely you're not going to get enough data to come up with a decent scale? What have I missed here?

[Wayno]

Originally Posted by dave-

My process is this: disable port injection. scale maf to center mass against the DI only (process separation). switch to 100% port... adjust port scaler/latency against the now-known-good MAF. recombine and fine-tune in the MAF scale.


But you can't just go 100% DI and then head out doing WOT runs to obtain logs and if you're only logging closed loop, surely you're not going to get enough data to come up with a decent scale? What have I missed here?

Quite a lot I'm guessing.

On NA, you can certainly go out with full 100% DI, scale the maf then adjust the port injector scales to match.

Now that you are FI, and especially since you seem to find it necessary to run bigger injectors, 100% DI won't have enough headroom to run, at power generating AFR's that is.

You could run 100% DI at high loads with vastly decreased timing, get the maf scale right then switch to PI to adjust the PI scalar.

Or you could run 100% DI up until a certain point somewhere between 3 and 4 MAFV, then adjust the PI scalar based on data ONLY up until that point, then adjust the MAF scale with both DI/PI combined after that point. This would be your best option.

[Kodename47]

You could scale DI in closed loop and then do the same for PI and it should give you the difference in scalar IF you have the latency set right. No need for OL really on a single set of injectors. You'll find it better to rely more on DI for very low load for idling etc with bigger port injectors. Make sure cranking tables are adjusted too

[steve99]

Originally Posted by dave-

Have an idle dipping/desire to stall on light throttle application after installing bigger injectors (ID850's). Car is turbo'd but didn't do it on stock injectors. At the time we'd loaded the SBD OFT map and just did some basic fuel and timing edits at WOT on the dyno to verify the turbo install was ok.

MAF is mounted just before throttle body and BOV is recirculating. There aren't any vacuum leaks that we can find. Not sure if MAF scale will fix it but I'm sure the hardware changes would benefit from a rescale. Would have been much easier to re-scale prior to putting the injectors in but bit late for that now.

But first post quotes jamesm saying something to this effect is possible with altered fuelling components and needing to isolate DI/PI for rescaling? Else where in the thread he goes onto say:

My process is this: disable port injection. scale maf to center mass against the DI only (process separation). switch to 100% port... adjust port scaler/latency against the now-known-good MAF. recombine and fine-tune in the MAF scale.


But you can't just go 100% DI and then head out doing WOT runs to obtain logs and if you're only logging closed loop, surely you're not going to get enough data to come up with a decent scale? What have I missed here?

If you assuke that the ID injector scaling is fairly goog and the fuel systems are faily balanced

you could try ztans trick and just run full di at idle and low rpm loads he ran into same issue

do all 3 pi\di tables, however i think you will be running much more port injection in mid upper rpm than in those tables

http://www.ft86club.com/forums/showp...6&postcount=21

[dave-]

Originally Posted by Wayno

Quite a lot I'm guessing.

That about sums it up. Can only end badly.

Car will go back under covers until I can find someone to do it properly.

[Wayno]

Originally Posted by dave-

That about sums it up. Can only end badly.

Car will go back under covers until I can find someone to do it properly.

You can do it yourself, you just have a long way to go, it's not that hard a process but if you're learning the tools to do it from scratch it may take a bit of effort.

You can't adjust the maf without injector scaler being correct, you don't know the value for the ports so you need to run 100% DI up to 5000 rpm or so, do the maf scaling, then switch to 100% port under 5000rpm and correct the port scaler against the correct maf scale.

You're lucky winter is coming and you can do it all around 20C and get a good result.

[dave-]

Ok lets see if I can get anywhere with this, apologies in advance for the TLDR...

SBD OFT Tune
http://www.datazap.me/u/dave/brzedit-turbo
Base timing was reduced and POL made a bit richer against wideband on th dyno otherwise nothing really changed, was just to verify install.
Log was done in BRZedit, think there were too many items selected as sampling rate isn't great.

I'd gotten some sort of MAF limit error which from memory was because LTFT had hit +30 or +40, not sure exactly. Between then and now, we found out that the primary O2 bung on the downpipe was too big and the sensor probably wasn't in far enough to be reading correctly.

99.95% sure we have O2 part sorted now as I have an LC1 wideband in the front pipe before cat and there isn't a lot of difference between them until going very rich which the factory sensor isn't capable of reading? I'd have that data in my tactrix log but can't find a 2.5mm stereo adapter smaller enough to fit in the LC1 socket.

Unfortunately before fixing all that, we put in the bigger injectors in preparation for more boost and E85, rookie mistake I know.

Current Tune
This was supplied a base tune that should be suitable for my turbo kit. It has been tweaked for the ID850 injectors. Car starts perfectly cold and hot so I think we have the cranking side ok?

This is immediately after flashing the file and leaving the car idle.
http://www.datazap.me/u/dave/base-tu...ed-id850s-idle

This is cruising around the car park and down the street. There are 3 logs, second and third are because the car stalled as per the hesitation mentioned on light throttle.
http://www.datazap.me/u/dave/base-tu...d850s-cruising

I then zero'd out the 3x DI/PI tables so we'd have 100% DI to see if anyone here could see something odd in the logs. 2 logs in the link, one idle and the other a light cruise. I'm not sure if it was my imagination but the idle dip issue did seem to go away.
http://www.datazap.me/u/dave/base-tune-di-only-id850s

[freerunner]

Originally Posted by dave-

Ok lets see if I can get anywhere with this, apologies in advance for the TLDR...

SBD OFT Tune
http://www.datazap.me/u/dave/brzedit-turbo
Base timing was reduced and POL made a bit richer against wideband on th dyno otherwise nothing really changed, was just to verify install.
[/url]

http://www.datazap.me/u/dave/brzedit...24&zoom=78-141

Is "afr lamda" the actual data of the wideband on the dyno? If yes it's running too lean.
If it is from the inbuilt "wideband" (stock front o2 sensor), I suggest you calibrate it against the wideband on the dyno. Makes everything a bit easier.
Else you newer know how it's actually running if you are off the dyno.
Take a look here

[dave-]

All logs there are using factory sensor, first one I believe is possibly compromised due to what I mentioned about the bung being too long compared to oem depth.

I can do the scaling against proper wideband once I get a 2.5mm cable to have the tactrix log the lc1 and saved to the same file.

[freerunner]

Originally Posted by dave-

All logs there are using factory sensor, first one I believe is possibly compromised due to what I mentioned about the bung being too long compared to oem depth.

Didn't catch that somehow. Nevermind. Your fuel trims are far off.

You definately need to get your LTFT close to zero while idling, crusing with steady throttle and slow acceleration. Don't mind the fuel trims on overrun (zero throttle) though.

With 100% DI, try to drive while keeping load < 0.7 for half an hour or so. Then take your log and scale closed-loop with help from vgi's mafscaling tool: link
Limit closed loop to 3.0V at first.

Add your new maf scale to your tune, go for another log. See if it's better.
If you're close to zero, go ahead and switch to 100% port injection.
Now look at your trims against the trims. Adjust "Port Injector Ratio BRZ" until you get the same trims like before.

Done.


EDIT: Just realized that you can't do that if your front o2 sensor doesn't work.

[dave-]

Very helpful @freerunner, will give that a shot when I get a chance.

Pretty sure the O2 sensor is ok but will grab a spare and do back to back testing to see if the data comes out the same before doing any changes.

[dave-]

Ok progress is slow but better than nothing!

Set all the DI tables to zero and put in ztans updated front O2 scale data.

Installed wideband in front pipe before cat, watching the display, the AFR values are close enough to the factory sensor so I'm confident it is not faulty.

Logs were too big for datazap so in the attached zip file.

Same POL table used in each case as only MAF scale was altered each time.

Filename: 800... Original ROM log and MAF scale for VGI's utility.
Went for a drive, mostly highway in 5th or 6th gear with cruise control set to ~100km/h then plugged the log (filename: 800) into VGI's tool to generate a new MAF scale for the next attempt.

Filename: 801...
This is the log after flashing the new MAF scale from previous data review. Same road but shorter.
This log showed the LTFT improve out of sight so thought I was on the right track. But plugging the data into the VGI tool said to make further changes, in some case by as much as 20% looking at the comparison feature. I did not use smoothing.

Filename: 802...
Log after next flash. Now the LTFT's are not so nice half way through the log. The car also had some noticeable hesitation at first throttle application and stalled on me once at the lights trying to take off.

So I am assuming I've gone in the wrong direction here? Thinking of returning to 801 scale and doing a lot more logging. Any pointers or comments before I keep going?

[freerunner]

Didn't take a look at the logs yet, on the phone right now.

Are you using the default settings in vgi tool?