RomRaider

It occurred to me about 4am that I need to adjust the scaling to better represent expected load values to my Transmission Control Computer... I noticed some strangely soft slow shifts yesterday when I was out tuning, and then at about 4am it finally dawned on me why that would be.

If anything I want load values reported a little bit on the high side rather than the low side so the trans shifts more firmly than normal to keep from burning up clutches and whatnot. I will start scaling up the MAF table until it brings one of my older tunes into a reasonable range, rather than what I did yesterday which was to adjust the main fuel and ignition timing tables to accommodate the low reported loads.

Great Excel sheet. But I would like to point out small error I noticed.

I tested my MAF with 1k resistor and at one spot I was getting every time 4.80 MAF volts and ~660 kg/h of airflow. I did my MAF scaling assuming that 1k resistor lowers the MAF voltage by 10%. And so seems your Excel do also. I then did new test run with resistor and new MAF table and I got 4.32 Volts and about that 660kg/h airflow at same spot several times. So that 10% of MAF voltage drop with 1k resistor is spot on. Same story all over the logs. So I would assume that as fact.

But then for stock MAF table the 4.80 volts gives 664,875 kg/h of airflow. Then with 1k resistor the MAF voltage is 4.32 but at that spot your Excel gives bit over 702 kg/h of airflow. Your Excel seems to be protected so I can't see how you have calculated that but the calculation seems to go bit off. I calculated mine by using the third order Polynomial Trendline Function in Excel. And It gives 673 kg/h of flow for that 4.32 spot. Which is still bit off. But not as much.

Here's bin where you can find my MAF table for stock 328I MAF and 1k resistor. With that resistor the max kg/h is somewhere between 1000-900kg/h but with 1000kg/h the curve looked to take off too quickly upwards. So the max is now 900kg/h at five volts which looks lot more reasonable. I have tested and fine tuned the below 725kg/h part to be almost 100% as the stock MAF. So no other tuning needed.

Some pic I took form the logs for proof:


At top RPM the curve with resistor is bit higher because I'm maxing my MAF.

I take that back. No error really. I just used the Excel wrong. And with more log reading, it looks like the difference that 1k resistor makes to MAF voltage is not 10%. It's more like 9%. And the Excel by ba114 uses that 9% voltage difference, so the result will be really accurate. Basically no fine tuning needed if someone adds 1k resistor and uses that Excel to calculate MAF table.

+10 for pazi88

Thank you

Installed the resistor today works great .

Hello Pazi, first off thank you for your many contributions to the BMW community.

Can you explain how you arrived at your MAF table ending in almost 900kg/h per your attached file? It looks like you multiplied the factory curve by ~1.24 whereas I would have thought a 1k ohm resistor would require a ~1.1 multiplication to scale. Am I missing something? Unless the factory MS41.0 curve is different from my MS41.1 curve. Thank you!

Thanks!

I have multiplied the voltage scale of the MAF curve by 0,9 because 1k resistor causes 10% drop of the MAF voltage. Then calculated the part that goes beyond 5 volts using Excel and third order polynomial function. If you just multiply MAF values by 1,1 you will distort the shape of the MAF curve and even get totally wrong MAF values in some points. It will require re-tune for all maps. In the way I have done there is no change in MAF values under 725 kg/h so no need for re-tune. As you can see from the pic I posted. The MAF curve with 1k resistor and without match almost perfectly.

Ahh, okay I missed that part. Thanks for explaining.

I will be fitting a Nissan slot MAF in the next few days thanks to the wealth of information in this thread (high five ba114). I will be sure to report back with my findings. Should that go smoothly, the next phase will be ordering up the FI parts!

I did assemble a MS2 v3.0 with intentions of making a PnP setup from a donor DME, but would much rather use factory tuning for drivability purposes.

Success! Pulled a MAF from a late 2000's Nissan Maxima this morning, dropped in the appropriate curve from ba114's spreadsheet and it runs nice and smooth. Have not road tested just yet.

https://youtu.be/i0RExLFfkJ4

If anyone is looking for wiring info, I connected from Nissan 22680-7S000 MAF to OBD2 E36 harness:

Pin 2 (r/g) to red - 12v
Pin 3 (blk) to brown and black bridged - ground
Pin 4 (g/or) to 2.2k resistor to yellow - MAF signal to DME

Pin 1 has no connection, and pins 5 and 6 are for intake temp sensor which is not needed.

glad to see its working for you. Now go make some logs with the stock injectors so you can dial in the MAF curve and update the scaling worksheet

Yes, getting on that soon!

What is the ID of your MAF housing? I'd like to keep consistent with your setup, to compare logs in the near future. I ordered a Treadstone MAF housing (http://www.ebay.com/itm/142380128468) which arrived today, but my straightener wouldn't fit into the pipe. I then put a caliper on it to find it is ~2.85" ID.

My MAF tube is 3" ID. The transfer sheet will work out the scaling for you if you input the ID of the tube you have.

Hi All,

Does anyone have MAF table for 540i MAF?

Pull the table from the alpina bin in the roms thread. It is close enough.

will it have a positive effect on a m52b28 with m50 manifold and m54b30 intake cam, catless exhaust(stock muffler)