MAP vs AFM - some examples

[Bugermass]

I tune alot of different kinds of cars, ask anyone thats been in our shop, we have both MAF and MAP based cars. Both styles of load input can be equal providing the ECU has proper compensations in place for each.. for example WRXs use the MAF as their main metering input.. but simular to the civics there are variances in airflow at certain RPM/Loads where reasonances and other weird airflow anomalies occur. If you try to account for these problems using the maf transfer table you'll end up with a stupid jagged maf curve. In a perfect world the maf curve should be smooth, but since this is not always the case the subaru ECU has a table called MAF Compensation. This table uses the map sensor as a load input for speed density type corrections in areas where the MAF signal is irregular. This allows a very smooth maf curve with slight corrections for airflow anomalies.

GM, FORD, BMW, VW, Toyota, Nissan, Mitsubishi, they all have MAFs and they all deal with them differently... One thing that really affects the stability of the MAF signal is where its located in relationship to the throttle body, bends in the intake pipe, air inlet etc.. You could add a simple air straightener and mabey make the pipe a little longer and probably have pretty good results with it. I plan on doing some testing with this on the civic once I get my hands on one with a flashpro for a few days. The reason, is while yes speed density it great and all, it takes ALOT more time to get dialed in when your dealing with variable valve lift and cam timing. For instance, on flash pro with SD/MAP setup you have to tune high cam and low cam for each range of cam angles. not only WOT but part throttle as well.. For anyone whos sat on a dyno and done this you know it takes a GREAT deal of time to get it all dialed in perfectly.. Now take a EVO10 for example.. it has variable cam timing on intake and exhaust and is maf based. So you get your maf curve dialed in for your setup (one table) get your target AFR table where you want it and now your free to move the cams around any which way you want without having to tune a different map for each angle. Why?? because airmass is airmass, it doesn't care what the cams are doing, if has X amount of airmass it will always give X amount of fuel. Imagine you have 2 cams both able to move 50deg + or - from 0.. You tell me how many maps you'd have to have to tune for that in a SD/MAP setup.. GM takes this even further, they actually have Timing vs Cam Angle, so you have your main timing table(s) based off Airflow and RPM, then you have timing adder tables that allow you to vary timing against your base timing table based on cam(s) position.. Try doing that with SD/MAP lol.. Realistically as much as I love standalones and SD/MAP based tuning, with all the variables there are to deal with in modern engines, Mass Air load referencing is the better way to do it.. It is more precise cause it measures the ACTUAL air "mass" going into the motor. With a map based setup you measure air "pressure" lets say 10PSI, but at 50deg, 70deg, and 90deg air temps the actual "airmass" will be different requiring different amounts of fuel to achieve the same final AFR. This fueling is based on a calculation of manifold pressure temperature, and baro pressure usually.. All tables that must be dialed in just right to be acurate.. With mass air, it measures the airmass directly and theres no guessing..

Obviously theres more to it, but the jist of it is that you can achieve equal results with either type of load input if the ECU is comprehensive enough to handle any anomalies. MAF tuning is generally a more efficient way to do it, especially with variable valve lift and cam timing.

So the real question is can Hondata write some code so we can use different mass air meters and be done with all the SD 10,000 maps nightmare. NisTune does it, HpTuners does it, SCT does it, UpRev does it, DiabloSport does it. I'm sure with some thought and time hondata could do it as well and improve the tuning experience for the Civics. Imagine being able to wire in a mass air from a Z32 (500HP capable) or a PMAS (1000HP capable), tune the maf transfer table, mabey a maf comp table and be done with fuel and free to move around the cam angle range and country (altitudes/temperatures) without having to tune a bunch of SD tables..

Just some thoughts..

[Bugermass]

Oh and if the intakes are causing problems then they need to be designed better. SD/Map tuning makes it too easy for anyone to cut and shape some pipe and sell it as a performance intake, its time people start actually doing hard core R&D and make stuff thats engineered properly not just thrown together, mass produced, and sold to turn a profit. Its not easy, we went through a few revisions to get our intake pipeing to play nice with the HHR mass air system, it just takes some honest dedication to making a quality product..

[VitViper]

I have SCT's software, it's a quality piece of work and puts anything currently available for MAF tuning Civics to shame.

[Bugermass]

Yup, theres no reason the civic ECU shouldn't be able to cope with MAF based fueling even with boost, its just a matter of time energy and well written software. Even DSM link can handle upgraded MAFs up to 1000HP and its very basic software.

[VitViper]

I guess that depends on what Honda implemented in the stock ECU. I do believe Hondata wrote their own injector code to get large injector support working.

SCT made this possible on my ZX2:

[Hondata]

Originally Posted by Bugermass

Yup, theres no reason the civic ECU shouldn't be able to cope with MAF based fueling even with boost, its just a matter of time energy and well written software. .

The biggest issue is the fuel system. Under boost the fuel pressure behind the injector drops and the fuel pressure before the injector increases. In essence the fuel injector gets smaller as the boost goes up.

Install a boost referenced return line fuel system and problems tuning an AFM boost calibration pretty much go away.

[mucter]

Originally Posted by Hondata

The biggest issue is the fuel system. Under boost the fuel pressure behind the injector drops and the fuel pressure before the injector increases. In essence the fuel injector gets smaller as the boost goes up.

Install a boost referenced return line fuel system and problems tuning an AFM boost calibration pretty much go away.

Aside from the other obvious issue with FPM not having AFM software released for the USDM market that supports larger injectors or expanded tables.

[Mikey6p]

Is there any risk of the ECU being less able to compensate for changes in altitude and air temperature when switching from a MAF based tune to a MAP based tune?

[soxfan143]

Originally Posted by Mikey6p

Is there any risk of the ECU being less able to compensate for changes in altitude and air temperature when switching from a MAF based tune to a MAP based tune?

No. There are tables for IAT compensation and the ECU has an internal altimeter to determine altitude or atmospheric pressure, and compensate for it.

[Zer0c00L]

Originally Posted by Hondata

The biggest issue is the fuel system. Under boost the fuel pressure behind the injector drops and the fuel pressure before the injector increases. In essence the fuel injector gets smaller as the boost goes up.

Install a boost referenced return line fuel system and problems tuning an AFM boost calibration pretty much go away.

who makes any of these for are civic?

[Bugermass]

Hondata, Are you guys planning on doing any updates to the Mass Air side of things?

[Stealthcivic]

Originally Posted by nunoctr

well i have a different point of view.

i have tuned my k20 cars for 4 years (i had a EP3 CTR with kpro before) and always used map tuning.

Now i have a fn2 ctr with maf and after i bought my Fpro I only tuned map (the only one i did know..)

After studing maf tuning, reading some posts os cobb users and some hondata posts in they forum i started to do maf tuning.

I have only a race header, exhaust, RRC manifold and spoon cams. Stock intake with M&M style scoop.

In the edyno my car have 249HP. The cars runs better than the tuned map cal i had. The gas mileage is better. The car is smother than stock. 13.0 AFR at wot and -1% Sfuel trim.

For me a good maf tune will give the same HP than a good map tune in a NA. car.

I agree with you man, I run the stock intake (there are no better intakes out yet!), vibrant race header, hfp suspension, progress rear sway, soon (since my clutch went out!- exedy stage 1 clutch and exedy flywheel.
I am having my car tuned by e-tunez (bv1) and I like the maf tune, idle's like stock, gas mileage stays decent (I travel a lot). Oil meter still works. Very smooth transmission when I had the maf tune. I liked it a bit more than Map. Now, these were both base maps that were created for me, that will be changed....I just like many things about the MAF tune- and yes I do have a stock si intake.

[w00t692]

You miss out on all the features of the Hondata MAP tuning portion of the software. If it wasn't for these features, i'd run a MAF tune as well.