RomRaider

This thread has been created to discover and document MAF transfer curves for the purposes of:
- Extending the range of a MAF through adding a resistor
- Extending the range of a MAF through increasing the tube size
- Retrofitting aftermarket and MAFs from other cars with known scalars

The current best choice for forced induction is the Nissan 22680-7S000 MAF from a 350z.
I pulled apart a stock 350z rom to get the 64 point scalar and converted it to a 256 point table.
This Hitachi MAF costs roughly $20 and i have tested and confirmed functionality with great results.

I have also included some PMAS HPX MAF scalars, along with a Ford 3" slot style MAF, which is pretty similar to the 350z Hitachi MAF.

Moved to github:
https://github.com/ba114

Update 18/11/2020:
Fixed issue with resistor changes calculation

Update 27/03/2020:
Minor update to background calculations only

Update 13/03/2020:
Attached updated v10 of the scalar spreadsheet.
- Added Bosch 0280217814 MAF from M62tu
- Added Bosch 0280218067 MAF from Audi RS4

Update 11/03/2020:
Attached updated v9 of the scalar spreadsheet.
- Added Bosch 803 MAF Scalar
- Cleaned up Hitachi MAF scalars, replacing all previous with the revision 3 scalar from v8 only.

Update 28/04/2019:
Attached updated v8 of the scalar spreadsheet.
- 3 new hitachi 22680-7s000 scalars added based on testing in a e46 330i. Revision 2 and 3 have got pretty consistent fuel trims within +/- 5% for all my testing upto around 2.7v. This is based on stock fuel tables scaled for use with 60lb bosch ev14 injectors. If anyone still has a stock setup and cares to test, please do.

Update 15/04/2019:
Attached updated v7 of the scalar spreadsheet.
- Added alternative scalar for hitachi MAF for idle testing.

Update 11/02/2018:
Attached updated v6 of the scalar spreadsheet.
- Fixed re-scaling of tables based on tube size changes

Update 10/02/2018:
Attached updated v5 of the scalar spreadsheet.
- General clean up
- Refined the scalar for Nissan 22680-7S000 MAF
- Added divisor function to 256 Point Scalar Modifier sheet for when you need to reduce the MAF kg/hr due to exceeding DME limits
- Added Alpina 3.5" MAF scalar (Pretty similar to stock MAF in 3.5" tube)
- Added RR 16x16 to 1x256 MAF table converter

NIssan 22680-7S000 wiring:
From BACK of PIGTAIL, reading RIGHT to LEFT
6-5-4-3-2-1

Pin 1 - EMPTY
Pin 2 - 12v
Pin 3 - Ground (bridge brown and black wires from MS41 harness)
Pin 4 - MAF signal to DME
Pin 5 - IAT
Pin 6 - IAT

You probably need to correct the checksums. Are you able to do that?

not at that point yet. Trying to understand the basics of tuning these ecu's/mafs first. My build isnt at the point of needing tuning yet i.e. engine is still on a stand, but as tuning this is going to be very different to what i know so far im just reading and trying to figure out as much as i can.

build is:
m52b28 (alu block) - i live in Australia
Stock internals
CES copper spacer and cutring gasket
PTE 6262 turbo

it's going in an e30.

if i can understand how this stuff works, i can start figuring out what MAF, injectors etc i need to source to continue to build.

Sounds like you have an old hpx spreadsheet. The 2014 hpx tool will pump out a full 256 table for you. Be sure to enter the inner diameter of your pipe.
http://pmas-maf.com/resources/PMASHPXTOOL2014_2.xls

With my 16g 3" aluminum pipe, my table exceeded 2048kg/hr in the last 5 or so cells which I just kept maxed out since I'll never reach those values. I could have ran a different coefficient to hangs the Maf tables max to 4096 kg/hr but I didn't see the need.

The logic change is all good to go. Just waiting on mrf to do a write up. I would do it but I'm horrible at explaining things of this nature.

Thanks for the spreadsheet, that should definitely come in handy.

I was using the values for a HPX sensor in 3" tubing using the values provided in the first link of the thread.
The good news is that the figures weren't off too drastically which means my logic would work if in worst case scenario i had to work it out myself for a non-HPX sensor, atleast to get within a reasonable ball park before fine tuning anyway.

Is this the slot style Ford 05+ MAF that is commonly referred to?

http://www.ebay.com.au/itm/191563792612 ... EBIDX%3AIT

Looks like it. You can pull the ford slot maf from basically any 05+ ford/mercury/lincoln as they all use the same maf just with different sized housings. Not sure about australia, but in the US you can get used oem ones for $10 shipped.

I'm willing to test the cheapies as I'm already set up using the slot-style maf on my setup.

Most transfer functions can be found here as stated in OP:
http://info.efidynotuning.com/maf.htm

Lets also make sure that we are referencing the proper MAF. We don't want the slot-style MAF equivalent to the chinese 3.5" HFMs that are junk. With that said, the $20 Chinese slot-style MAFs may be just fine but we need the right transfer function to accurately test it.

--

Lets talk MAFs
From this link:
http://www.sx.com/forums/viewtopic ... 94&t=57942
There is some unconfirmed information pertaining to different Hitachi slot MAFs. I've had trouble finding concrete information.

Have created an updated scaling sheet. hopefully it's of use to some people.

Found the what i believe to be the MAF table in a Nissan 350z rom dump.
From what i've read, the stock MAF tube appears to be around 72mm, which after scaling, would make this basically the same as the ford '05 slot maf.

I've attached the 64 values from the rom; i'll work on converting this into a 256 value table.

The part number is 22680-7S000 and can be had brand new for ~USD$20.

v3 updated with the Nissan slot MAF i bought and converted the 64 point scalar from the nissan rom dump to a 256 for our cars.

As mentioned, its basically the same as the ford 05+ slot maf once you plug it into a 3" tube as per the ford docs.
i'll do some logging once i have a running car to do a function for the in built IAT too.

This sounds awesome. Really hope it works, as it would open things up nicely if a proper MAF was only $20 vice $300+

That spreadsheet is brilliant!!

Did you develop the table of values for the 2.2k resistor? Is it known good, or in need of testing?

Last question I promise! Which signal wire does the resistor interrupt?

Just multiply the MAF table by 1.22 (adding 22%) for the 2.2k resistor. You will need to retune everything.

The resistor goes on the only signal wire from the MAF.