MAF and AFM specs

[CrazyJew89]

Alright guys. I have started working on making a proper MAF conversion for my car without chipping the ECU :D. I have a collection of the parts that I need to do this, including: a Ford MAF, Bosch MAF, and Ford air temp sensor. However, I am lacking some information about the signal coming from the MAF, the AFM, and the temp sensor that I will be using.

Bosch MAF:
Bosch #: 0 280 213 011
BMW #: 1 730 074
Need the voltage vs. mass flow

Bosch AFM:
Bosch #: 0 280 202 082
BMW #: 12866159
Need the voltage vs. air speed

Walbro Ford MAF:
Walbro #: AFH70-04B
Ford Service Part #: F5VF-12B579-BA
Need the voltage vs. mass flow

Ford Air Temp Sensor:
Need the resistance vs. temp

I have searched high and low on the internet and called BMW and Bosch for this information and gotten nowhere :(. If anyone has any of this info or has any ideas on where I could go to get it that would be very helpful.

[downernsp]

Miller Performance sorry to be blunt.

[CrazyJew89]

Its ok thats the response I was expecting. I would go w/ miller but I really don't want to chip my ECU and I have no money.
Looks like I'm going w/ the wind tunnel aproach

[Aptyp]

i thought it's been done by someone already, and that there was a right up.

[nando]

if you aren't going to chip it what is the point

you need more advance to get more power. putting a MAF on an otherwise stock engine is a dead end.

also why would you use a Ford temp sensor.. just gut one out of an old AFM. You aren't going to be able to make a different temp sensor work with the stock computer, because they use different bias resistors and very different resisitance curves.

also the stock AFM doesn't measure speed. it measures pressure, like a MAP sensor. the temp sensor is then used to calculate mass. That is the biggest problem with trying to use a MAF with no changes in the computer.

[badvibrations]

miller performance sorry to be blunt.

+1

[CrazyJew89]

i thought it's been done by someone already, and that there was a right up.

I have seen several write ups on MAF conversions. Every version I have seen forgets to compensate for something. Example take voltage readings from the AFM at all RPMs and make the voltage from the MAF match using a look up table. The problem is he forgot to account for the fact that a change in temperature will change the voltage coming from the MAF but it will not change the voltage coming from the AFM.

if you aren't going to chip it what is the point

you need more advance to get more power. putting a MAF on an otherwise stock engine is a dead end.

The initial point of this project is for increased driveability in the upcoming winter seeing as this is my daily car. Also, I did not realize until you mentioned it that the timing was controlled by the ECU. (The cars I have worked with in the past, the timing is adjusted mechanically)

also why would you use a Ford temp sensor..

I would be using a Ford temp sensor because in the US specs on domestic parts are better documented and I need a way of measuring the temp for my calculations. So that I can convert the mass air flow signal into a velocity signal for the ECU.
I will be using a stock temp sensor to send a temp signal to the ECU.

also the stock AFM doesn't measure speed. it measures pressure, like a MAP sensor. the temp sensor is then used to calculate mass. That is the biggest problem with trying to use a MAF with no changes in the computer.

I was unaware that the AFM measured pressure rather than speed because everything that I have managed to find online has told me that this car runs off of a speed density system and that the AFM measures speed.
If what you say is true that the AFM does measure pressure why does everyone try to switch to a MAF instead of running an electronic pressure sensor?

[nando]

I have seen several write ups on MAF conversions. Every version I have seen forgets to compensate for something. Example take voltage readings from the AFM at all RPMs and make the voltage from the MAF match using a look up table. The problem is he forgot to account for the fact that a change in temperature will change the voltage coming from the MAF but it will not change the voltage coming from the AFM.

but you can't just measure RPM, because the is also load to consider, which is what the AFM really measures. The other, bigger issue is the AFM is completey ignored past 70% load. You would have to figure out what that meant for the MAF and set up your correction curve to match that. Basically past 70% the AFM is maxed out (the door is open all the way) and the ECU uses assumptions about how much air is passing through at WOT to calulate fuel and timing. Modern ECUs that come with MAFs don't do this, they are always measuring the air mass/load of the engine regardless.

The initial point of this project is for increased driveability in the upcoming winter seeing as this is my daily car. Also, I did not realize until you mentioned it that the timing was controlled by the ECU. (The cars I have worked with in the past, the timing is adjusted mechanically)

yes it's entirely controlled by the ECU. It also uses the AFM/RPM to adjust timing
like the VE map.

I would be using a Ford temp sensor because in the US specs on domestic parts are better documented and I need a way of measuring the temp for my calculations. So that I can convert the mass air flow signal into a velocity signal for the ECU.
I will be using a stock temp sensor to send a temp signal to the ECU.

makes sense

I was unaware that the AFM measured pressure rather than speed because everything that I have managed to find online has told me that this car runs off of a speed density system and that the AFM measures speed.
If what you say is true that the AFM does measure pressure why does everyone try to switch to a MAF instead of running an electronic pressure sensor?

yes, you are right - speed/density refers to the speed of the engine in RPM and the density of the air calculated with pressure and temperature. a MAF works slightly different because it measures the actual mass flowing through th engine. they are both technically speed density algorithms though, just different execution.

MAFs seem to be perceived as the holy grail along with things like ITBs. for certain the AFM is a restriction, but there is a lot of misunderstanding and confusion as to how the stock engine actually works. it's taken miller several years developing their kits to work halfway decent. Years ago it was the split second kit but because of the way it worked you had to adjust a knob on the thing every time the weather changed to dial it back in..

[downernsp]

Look time is money, by the time this actually happens or you do it, one could of saved some feria and bought the Miller one. Think about it if it was that easy there would be hundreds of threads and already in you car,so just save feria and buy the miller on $295 is all it cost good luck when decision.

[CrazyJew89]

nando,
you still didn't answer my question.
Why doesn't anyone use a MAP sensor to replace the AFM?

[Hellabad]

nando,
you still didn't answer my question.
Why doesn't anyone use a MAP sensor to replace the AFM?

The true answer is that a half decent AFM is better than a quarter decent MAF.
(assuming you meant MAF instead of MAP)

here are some specs for you to get started with:

http://www.modifieda4.com/web/archive/sensors_airmass.pdf

http://modshack.info/images/sensors_airmass.pdf

thats a good link, cut and paste if doesnt roll over right away
Jay from GC

[JTapper]

Miller makes a great kit IIRC that includes a WAR chip, and their conversion kit. It'll cost significantly more, but I think you would realize a greater gain by using a proven setup.

[CrazyJew89]

The true answer is that a half decent AFM is better than a quarter decent MAF.
(assuming you meant MAF instead of MAP)

here are some specs for you to get started with:

http://www.modifieda4.com/web/archive/sensors_airmass.pdf

http://modshack.info/images/sensors_airmass.pdf

thats a good link, cut and paste if doesnt roll over right away
Jay from GC

Thanks for the links. I'll have to figure out if that is for the same MAF I have.

However, I did mean MAP (manifold air pressure) and not MAF (mass air flow)

[nando]

maybe because people don't understand what MAP is. I have heard it suggested before. But like I said - MAF is seen as a holy grail of sorts, so nobody considers anything else.

You'd still need a MAP that output the same curve as the AFM. I think they all tend to be 0-5v though. I'm wondering what the stock MAP that came with my MS looks like..

[CrazyJew89]

Well, a MAP seems like a much better way to go. Within a month I should be able to get a MAP sensor from a GM of something in the junk yard and measure both the voltage outputs and let you know what I find