MAF housing

[denso]

Hi, im currently maxing out my MAF with 0.35bar of boost at 7000rpm. I got a 2,75" MAF housing at the moment - is there a way to rise the boost without changing the hardware? Will a (new) rescaling of the MAF sensor help?

[BRZoomTX]

Have a 3" MAF housing made, then rescale your MAF to suit the new housing. You should be able to run in the 15-18psi range out of the stock MAF with a 3" housing without pegging the sensor.

An alternative is to try an Impreza MAF, which another member claims is plug and play. I would recommend rescaling your MAF with this too however, but the thread is here:

http://www.ft86club.com/forums/showthread.php?t=106496


Last option is to run speed density if you are on EcuTek. Running full time speed density will allow you to remove the MAF altogether, if you use a separate intake temp sensor.

[Kodename47]

0.35bar? Seems low to hit the max.

You need to change the MAF scale and the MAF limit parameters. How are you running boost without a change to the map?

[denso]

Originally Posted by Kodename47

0.35bar? Seems low to hit the max.

You need to change the MAF scale and the MAF limit parameters. How are you running boost without a change to the map?

http://datazap.me/u/denso/19092016?log=0&data=7

this is a actuall log of my car. Maybe the MAF senor isnt scaled "good enough" at the moment? im on a gt30 turbo with .70ar comp. housing and .69ar turbine housing.

thanks guys

[Kodename47]

@denso you're hitting 5v on the sensor, so it's not as I originally suggested. As you're running ECUtek I would suggest running SD. You could also increase the intake pipe diameter or even possibly change the MAF sensor. I believe there's a compatible Subaru MAF sensor that will give lower voltages for the same airflow.

[denso]

Originally Posted by Kodename47

@denso you're hitting 5v on the sensor, so it's not as I originally suggested. As you're running ECUtek I would suggest running SD. You could also increase the intake pipe diameter or even possibly change the MAF sensor. I believe there's a compatible Subaru MAF sensor that will give lower voltages for the same airflow.

@Kodename47 Yes, I know this (5V)...

So re-rescaling atm is not an option? Im on ECUtek, but I dont have an aftermarket MAP sensor for SD and Im not able to tune SD with my licence.

Do I need to rescale MAF again if Im going with a 3" pipe instead of 2,75"? I think yes.

[DJCarbine]

Originally Posted by denso

@Kodename47 Yes, I know this (5V)...

So re-rescaling atm is not an option? Im on ECUtek, but I dont have an aftermarket MAP sensor for SD and Im not able to tune SD with my licence.

Do I need to rescale MAF again if Im going with a 3" pipe instead of 2,75"? I think yes.

If you go from stock to 3" maf you will have to scale, as the new maf would be reading less than your original for any given amount of airflow

[Kodename47]

Originally Posted by denso

So re-rescaling atm is not an option?

No, rescaling changes the calculated g/s per voltage of the sensor. You can't change the voltage output of the sensor itself.

[aagun]

what is here the MAF cant read the boost . so SD mode is the best option here

[denso]

Originally Posted by Kodename47

No, rescaling changes the calculated g/s per voltage of the sensor. You can't change the voltage output of the sensor itself.

What if I change the maximum of 280 g/s at 5V to 320 g/s at 5V?

Originally Posted by aagun

what is here the MAF cant read the boost . so SD mode is the best option here

MAF read the airflow and temperature. I cant go with SD.

[steve99]

Originally Posted by denso

What if I change the maximum of 280 g/s at 5V to 320 g/s at 5V?




.

Wont work mate, you would just be miss calibrating the maf and your fueling and load calculations will be will be wong. as you would be telling the ecu an incorrect mass of air entering the engine.

The maf is kind of measuring the velocity of the air passing the sensor. You know the size of the tube the sensor is in so you can calculate the volume\mass of air passing (offsets due to temperature and pressure done via map and iat sensors).

The maf scale table is the way the ecu calibrates the voltage provided by the maf sensor ( ie the velocity of air passing sensor) that produces the output volts is turned into a mass of air number in g\s. This table is only valid when using the correct maf sensor and the correct size maf tube.

So for a given velocity the maf sensor produces a cerian voltage, once the velocity hits a certian value and the sensor is maxed out ie reading 5volts thats it , no more flow can be read by the sensor..

You then need to change something

the size of the maf tube ie make it bigger so velocity is reduced and same sensor can be recalibrated for new tube size ie lower velocity of air past sensor now equates to a larger mas of air and hence less volts for same mas of air flowing past sensor.

or get a different maf sensor like the forester\wrx one thats plug compatable but is able to read about 30% higer flow rate for the 5v output, again you have to recalibrate for new sensor. But you wont need to alter your maf tube size. Assuming you only need 30% more flow

If you simply alter the g\s without changing anything your just going to get an incorrect mas of air reading.


[ame]https://m.youtube.com/watch?v=fjZljsTT8Jw[/ame]

[Kodename47]

Originally Posted by aagun

so SD mode is the best option here

Not if he's running the OEM MAP sensor and more boost than 0.35bar

[denso]

Originally Posted by steve99

Wont work mate, you would just be miss calibrating the maf and your fueling and load calculations will be will be wong. as you would be telling the ecu an incorrect mass of air entering the engine.

The maf is kind of measuring the velocity of the air passing the sensor. You know the size of the tube the sensor is in so you can calculate the volume\mass of air passing (offsets due to temperature and pressure done via map and iat sensors).

The maf scale table is the way the ecu calibrates the voltage provided by the maf sensor ( ie the velocity of air passing sensor) that produces the output volts is turned into a mass of air number in g\s. This table is only valid when using the correct maf sensor and the correct size maf tube.

So for a given velocity the maf sensor produces a cerian voltage, once the velocity hits a certian value and the sensor is maxed out ie reading 5volts thats it , no more flow can be read by the sensor..

You then need to change something

the size of the maf tube ie make it bigger so velocity is reduced and same sensor can be recalibrated for new tube size ie lower velocity of air past sensor now equates to a larger mas of air and hence less volts for same mas of air flowing past sensor.

or get a different maf sensor like the forester\wrx one thats plug compatable but is able to read about 30% higer flow rate for the 5v output, again you have to recalibrate for new sensor. But you wont need to alter your maf tube size. Assuming you only need 30% more flow

If you simply alter the g\s without changing anything your just going to get an incorrect mas of air reading.

Thanks mate. So getting a bigger MAF tube and recalibrating again is the way to go I guess.
@Kodename47 yes Im on the stock MAP sensor.
My target is 0,7bar (~10psi) but SD is still not an option.

Thank you guys very much. Appriciate your help.

As you can see I hit my current boost target really late (WG on spring pressure) because I adjusted the WG actuator "for safeness" during tuning. The WG is not fully closed cause of less spring pressure (spring pressure is adjustible).

[aagun]

Originally Posted by Kodename47

Not if he's running the OEM MAP sensor and more boost than 0.35bar

so should change to higher rate capacity map .