MAF Calibration 101

VersaTuner for Mazdaspeed6, Mazda 6 MPS, Mazdaspeed3, Mazda 3 MPS, CX7
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richy-m-g
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Joined: February 10th, 2013, 6:19 am
Location: Sherwood Forest, UK

Re: MAF Calibration 101

Post by richy-m-g »

I'm a Versatuner Virgin; please be gentle. I've cleaned the MAF sensor, I have not flashed the ECU or installed Versatuner. Car is standard UK MPS 6. I've hooked the laptop up with the cable and ran the car for 30 miles mixed driving. I still have some more driving to do as the LTFT is around -9.6. I get a MAF voltage of about 1.3 at tickover. Why isn't it 0.039 like in your chart?
mituc
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Re: MAF Calibration 101

Post by mituc »

Those MAF voltage points are so dense to provide an as smooth as possible curve even if the points there are discrete. Based on the MAF voltage points and the MAF g/s values the ECU logic will interpolate the actual MAF curve.

LTFT's of -9 are characteristic to winter time, so don't worry. However, give it more time and more miles of mixed driving to see where you actually are. If you have the stock air box I'd say it's safe to leave the MAF cal untouched for now.

Good luck!
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
MPS2NV
Posts: 29
Joined: January 14th, 2013, 6:15 am

Re: MAF Calibration 101

Post by MPS2NV »

Just a quick one, is there any word on progress for the smoothing feature? I have updated to the latest version of VT but haven't noticed anything for smoothing...
Also in reference to MAF cal 101, if I cant fill every cell but can fill every 2nd or 3rd cell with new g/s calculation how do I interpolate between cells? Im not sure if I am misunderstanding or if the feature isnt working. I dont mind trying to fill every cell individually but if I cant how do I tackle that?

Thanks!

Mitch :biggrin
MPS6, CP-e 3.25 maf-TIP-HPFP-injector seals-DP-TMIC-Magnum pistons,DNP manifold,Corksport CBE,ATP GTX3071r,Carrillo H beam rods, ARP main/head studs, GS BCS,Turbosmart BOV,Ported manifolds/head,engine balanced
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Steve @ VersaTune
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Joined: March 29th, 2010, 12:58 pm

Re: MAF Calibration 101

Post by Steve @ VersaTune »

MAF table smoothing is still on the feature request list.
In the mean time, you can cut and paste the table data to your favorite spreadsheet application and manipulate the data how you like. Paste the data back into tune editor once you have it how you want it.
johnrw
Posts: 6
Joined: May 3rd, 2013, 2:14 pm

Re: MAF Calibration 101

Post by johnrw »

Dumb newbie question which has probably already been answered but I can't obviously see it, do I need to do the MAF calibration with a stock intake, just bought versatune today and installed the high load map.

Thanks,
John
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Steve @ VersaTune
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Re: MAF Calibration 101

Post by Steve @ VersaTune »

Welcome to the wonderful world of VersaTuner.

It shouldn't be required if all is well. It's a good idea to do a few MAF Cal type logs to ensure that everything is in proper order. LTFTs +/- 5% is considered good.
EPTSpeed3
Posts: 17
Joined: February 20th, 2013, 8:30 pm

Re: MAF Calibration 101

Post by EPTSpeed3 »

Any tips on doing the closed loop logs? I cant seem to keep the pedal steady enough to make a stair case log of the maf voltages. They're all over the place. Also once I hit a certain point the car switches to open loop and I can do wot logs. How do I get the car back into closed loop? That part has me kinda confused.... Complete noob at maf cal s.
mituc
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Re: MAF Calibration 101

Post by mituc »

Put it in 2nd gear and press de acceleration pedal from like 1200-1300rpm up, gradually. Watch the load and make sure it doesn't go over like 0.8, in 2nd gear a load of 0.7-0.8 is enough to get you to red line.

If your car has cruise control then activate it at the lowest speed possible (20mph/32kmph) in 2nd gear, and then press "Accel" twice per second or so until you enter open loop (which may happen around 5000-5500rpm anyway, depending on the tune).
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
EPTSpeed3
Posts: 17
Joined: February 20th, 2013, 8:30 pm

Re: MAF Calibration 101

Post by EPTSpeed3 »

Cool thanks for the tip! I thought about cruise control. Ill give it another shot. How do I go back to close loop? Guess I still dont under stand close loop and open loop
mituc
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Joined: December 17th, 2011, 2:47 pm
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Re: MAF Calibration 101

Post by mituc »

The ECU enters the closed loop or open loop mode depending on various parameters. Usually in closed loop the ECU aims for maximum efficiency, minimum fuel consumption and emissions, while in open loop it aims for best performance.

Now, if you loop under the Absolute limits section in versatuner you will see there a lot of tables used to tell the ECU when to enter open loop or closed loop based on various parameters (acceleration pedal position, absolute load). When at least one of those conditions is met the ECU will move from closed loop to open loop.
When it's in open loop the ECU will use the open loop tables for fueling and ignition. You can make these tables to mimic each other on the overlapping sections for better tune consistency and smoother transitions.

Anyway, the MAF tables are not OL/CL specific. But some air flow values (and the corresponding MAF voltage values) are specific to one of these modes. So the values up to 120-150-180g/s (depending on your tune and mods) should be calibrated in closed loop and the rest of the values scaled accordingly (say, if the highest value you get while still in closed loop is 150g/s then go back a few cells, see the deviation trend from the stock values for, say, 140-145g/s, and apply that multiplication factor manually to the rest of the values up to the maf voltage scale limit).
Once the closed loop (CL) values are fine you can start calibrating the MAF for open loop (OL) and do a few WOT pulls so the the deviations from the target AFRs.
2008 Cosmic Blue Mazda 3MPS
Built engine + WMI + GTX3071 gen2, ~509BHP @34PSI
2008 Icy Blue Mazda CX7
Stock engine and exhaust (YES!!), JBR3" + GTX2867 gen2 + Autotech HPFP, self-tuned to 330-ish BHP
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