Please Read --> MAF Sensors with the EMS - Great Thread!

[MNGSX]

I like how the discussion progressed into covering pros and cons of each from a neutral stand point.

There is a reason why vehicles are manufactured with MAF systems in the first place.   They are flexible and accurate.

There is a reason why as people modified their cars in the MPFI early ages that they switch to speed density.  Despite it's flexibility and accuracy there comes a point that it is limited and restrictive to airflow. There were also few uptions in parts that were less restrictive and limited.

There is a reason why you will likely see more and more MAF systems in modifed cars.  Large Hotwire MAF's on translator boxes or wired directly to the ECU have become available that can handle large volumes of airflow with little impediment to airflow.


I'd like to see a flow bench of a UICP thru  a tb with a blow thru MAF and without.

Perhaps have the MAF in two places.  I have a hunch it would flow best right before the throttle body since flow thru the maf gets split in two main paths much like flow around the TB butterfly.   Putting one in front of the other I believe will be more efficient as air flow only gets divided once.

As for MAF or MAP...  For an all out drag car or something I would'nt bother with MAF.  

For a street car, auto-x or road racing car I would go MAF.  There are alot more things to tune for than just a WOT blast.  I think if you do it right with everything here the advantages of MAF greatly outshine a MAP system.  

One advantage to a non airflow restrictive MAF on a aftermarket ECU is that you can set a "clamp" point at which you can switch over to SD (MAP).    This is nice in that you get the advantages of both.   When resolution at high boost or high airflow (NA engine) gets a little grainy you can have it operate as a speed density system..  Yet when you are'nt so far into the skinny pedal.

This may not be necessary depending on MAF size vs power level.  Another factor is maf type like Hotware vs Kar-hz.    

Alot of things have changed since the days when SOP was MAF could'nt cut it and was'nt even considered.   Many varied options are available to choose from now so expect to see them.


On a drag race car or any other type of racing that requires nothing more than a passable idle and a WOT blast MAP is just fine and MAF is'nt much of an advantage if any.  

You can use IAT (intake temp) and BAR as adjustments to a MAP systems fuel and igniton map values.   So changing climatic conditions can be delt with automatically via the ECU.  

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[SA]

Thanks MNGSX!  Great contribution   .

SA

[v10man]

Just something to think about , the newer Big Rigs have alot of computer engine controls. Deisel engines have no vacuum, there for I would bet they are using a MAF sensor. The size of these should handle super power levels.
Chris

[anoldsman]

I have a Univer 3" 0-5v MAF installed on my 1G DSM.  I have tried everything to get the EMS to recognize the signal but it is not working.  The EMS shows 4.98-5.00 volts when I select MAF.  When I select MAF Vortex, as suggested by the EMS tech line, there is a voltage reading but it is way off.  The car will start but not run well for long.  Since the factory setup is for Hz, I moved the wire to the Baro voltage input and now I can monitor the voltage correctly.
  How do I get the EMS to recognize the Baro voltage input as my MAF input?  Or, do I have to wire the MAF input to where the MAP input normally is?  I guess that would work.  I would just have to convert that voltage in my logs to see the pressure.  However, I would prefer to leave that alone and use the Baro voltage input.

Chris

[Mello]

You might be able to get things going by experimenting with one of the choices in the option "MAP Analog input".  One of your choices is barometer voltage (as well as may others).  I haven't really had time to review all of the choices available; though this is a good place to start (maybe).

[anoldsman]

You might be able to get things going by experimenting with one of the choices in the option "MAP Analog input". One of your choices is barometer voltage (as well as may others). I haven't really had time to review all of the choices available; though this is a good place to start (maybe).

Thanks for the help.  I looked to see if there were any other Analog Inputs that I could use and I found User #1 Analog Input.  Do you know where that is wired in?  Basically I would like to keep both the MAP and the MAF in and just switch back and forth to see which works best.  If I use the MAP Analog Input for the MAF voltage then I would have to switch the wires every time that I switch from MAP to MAF or MAF to MAP.

Chris

[TPW]

I believe the only way it is going to work on your particular application is thru the differential pressure sensor. But you have the MAP there now if I'm not mistaken.
Let us know how you make out with the alternate analog input. I'm curious to see how you can set that as your load input without a software change.

[anoldsman]

Well I finally got the car wired properly with help from Scott.  I set up the calibration to run rich, around 11:1 AFR at WOT.  I went for a ride and I saw 15:1+ AFR at WOT before I shut it down.  I logged the drive and exported it to Excel to see what I did wrong.  I found out that the EMS was not showing the correct Load based off of the MAF transient function that I entered.
  I called Scott and he informed me that they set up the MAF systems to vary by rpm.  Basically you use this formula - ((25600- RPM)/25600) * Load %  = MAF as Load.  The 25600 is the maximum rpm allowed by the EMS.  This seems totally wrong to me but, that is how the system works.  I will try to convert my calibration to this style but I do not know if it will work.  
  I believe that a direct correlation from voltage to load, like that used for the MAP systems, is the better way to do it.  However, I know that there are many users currently using the system as is and changing their maps to my way might be a problem.
  If you agree with me, please let AEM know.  They are willing to change the software to the direct method if people request it.  I also want to add my thanks to Scott for going out of his way to help me with this issue.

Chris

[SA]

For a given fixed total mass airflow indication from a MAF sensor, as engine speed increases, the amount of air that enters each combustion chamber per engine cycle decreases...meaning the required fuel flow will decrease as well.  That's why the load calulation is scaled with engine RPM.

SA

[DG-FNR]

Note that on Mitsubishi motors with a Karmann Vortex sensor (1G, 2G DSM and Stealth/3000GT for sure) that sensor is NOT a MAF - it is a VOLUME sensor.

So what? It needs to have the AIT and Baro pressure maps properly populated or the calibration will be off.

DG

http://farnorthracing.com

[JulianSerna]

I have the Ford Lightning 90MM MAF sensor, and I did happen to find the volts vs. mass air flow charts on the internet, but for the life of me, I do not know how to use/convert this information to tune my AEM. What I mean is, if it a certain voltage the calibration table indicates X amount of air flow, how am I suppose to convert that air flow to the AEM's pounds per minute? I know air has weight to it, that is why cold air weights more than hot air -- basement apartments are always colder than attic apartments if running no AC and all windows closed.

Any how, if there is a formula out there to convert air flow to pounds per minute, I would greatly appreciate it. I am currently tunning my car off a GM 3-Bar MAP sensor, but I would not mind playing around with the MAF just for the sake of gaining more knowledge -- it is still in the car and hooked up, so why not?

Sincerley,
Julian Serna

 

[J. Fast]

I have the Ford Lightning 90MM MAF sensor, and I did happen to find the volts vs. mass air flow charts on the internet, but for the life of me, I do not know how to use/convert this information to tune my AEM. What I mean is, if it a certain voltage the calibration table indicates X amount of air flow, how am I suppose to convert that air flow to the AEM's pounds per minute? I know air has weight to it, that is why cold air weights more than hot air -- basement apartments are always colder than attic apartments if running no AC and all windows closed.

Any how, if there is a formula out there to convert air flow to pounds per minute, I would greatly appreciate it. I am currently tunning my car off a GM 3-Bar MAP sensor, but I would not mind playing around with the MAF just for the sake of gaining more knowledge -- it is still in the car and hooked up, so why not?

Sincerley,
Julian Serna

Since you have the voltage to air flow conversion charts, the most updated resource I've personally read is Greg Banish’s 2009, Designing and Tuning High Performance Fuel Injection Systems (SA161).  Chapter 4 in his book is dedicated entirely to V.E. Equation and Airflow estimation.  The math you're inquiring about is there. You can also use any College Thermodynamics, Physic's or SAE desk reference for constants, equations, and the same conversions.

Well I finally got the car wired properly with help from Scott.  I set up the calibration to run rich, around 11:1 AFR at WOT.  I went for a ride and I saw 15:1+ AFR at WOT before I shut it down.  I logged the drive and exported it to Excel to see what I did wrong.  I found out that the EMS was not showing the correct Load based off of the MAF transient function that I entered.
  I called Scott and he informed me that they set up the MAF systems to vary by rpm.  Basically you use this formula - ((25600- RPM)/25600) * Load %  = MAF as Load.  The 25600 is the maximum rpm allowed by the EMS.  This seems totally wrong to me but, that is how the system works.  I will try to convert my calibration to this style but I do not know if it will work. 
  I believe that a direct correlation from voltage to load, like that used for the MAP systems, is the better way to do it.  However, I know that there are many users currently using the system as is and changing their maps to my way might be a problem.
  If you agree with me, please let AEM know.  They are willing to change the software to the direct method if people request it.  I also want to add my thanks to Scott for going out of his way to help me with this issue.

Chris

arnoldsman, were you just generating a best guess slope for Karmen Vortex VAF, hotwire MAF, and hotfilm MAF systems and defining your own step increments by interpolating and scaling with load to RPM?

I like how the discussion progressed into covering pros and cons of each from a neutral stand point.

There is a reason why vehicles are manufactured with MAF systems in the first place.   They are flexible and accurate.

There is a reason why as people modified their cars in the MPFI early ages that they switch to speed density.  Despite it's flexibility and accuracy there comes a point that it is limited and restrictive to airflow. There were also few uptions in parts that were less restrictive and limited.

There is a reason why you will likely see more and more MAF systems in modifed cars.  Large Hotwire MAF's on translator boxes or wired directly to the ECU have become available that can handle large volumes of airflow with little impediment to airflow.


I'd like to see a flow bench of a UICP thru  a tb with a blow thru MAF and without.

Perhaps have the MAF in two places.  I have a hunch it would flow best right before the throttle body since flow thru the maf gets split in two main paths much like flow around the TB butterfly.   Putting one in front of the other I believe will be more efficient as air flow only gets divided once.

As for MAF or MAP...  For an all out drag car or something I would'nt bother with MAF.   

For a street car, auto-x or road racing car I would go MAF.  There are alot more things to tune for than just a WOT blast.  I think if you do it right with everything here the advantages of MAF greatly outshine a MAP system.   

One advantage to a non airflow restrictive MAF on a aftermarket ECU is that you can set a "clamp" point at which you can switch over to SD (MAP).    This is nice in that you get the advantages of both.   When resolution at high boost or high airflow (NA engine) gets a little grainy you can have it operate as a speed density system..  Yet when you are'nt so far into the skinny pedal.

This may not be necessary depending on MAF size vs power level.  Another factor is maf type like Hotware vs Kar-hz.   

Alot of things have changed since the days when SOP was MAF could'nt cut it and was'nt even considered.   Many varied options are available to choose from now so expect to see them.


On a drag race car or any other type of racing that requires nothing more than a passable idle and a WOT blast MAP is just fine and MAF is'nt much of an advantage if any. 

You can use IAT (intake temp) and BAR as adjustments to a MAP systems fuel and igniton map values.   So changing climatic conditions can be delt with automatically via the ECU.   

MNGSX, regarding your statement for a non restrictive MAF, or VAF, DG mentioned a 3000gt has a Karmen Vortex and they are non restrictive.  Is this the setup to which you were referring? How do you assign a clamp point on VAF and switch over to speed density?

Jeremy