Skool me: MAF vs MAP

[-Scott-]

What are the pros & cons?

MAF sensors appear to be a little "fragile", and (in my application) a PITA to fit somewhere.

MAP sensors are (as far as I know - which is where I may be wrong) small & simple to implement.

Given so many OEM installations use a MAF sensor I'm guessing that they offer significant benefits - like what? I guess they can compensate for altitude?

If I throw away the factory ECU and install an aftermarket ECU (yes, I know that would be wrong) what do I lose by using a MAP sensor instead of the MAF sensor?

[tweak'e]

i'm a little rough on th details, hopefully someone wil fill in the details soon.

MAF generally also has air temp sensor built into it as well. it gives a much more accurate measure of the amount of air going into the motor.
MAP is a bit crude in comparison. they only measure pressure. also i think (depending one application etc) they are not very accurate at one end of the scale ie read high boost pressure fine but poor on low boost. ecu uses pressure reading and intake air temps to estimate what the mass of air flow is.

ecu also has altitude sensor. if i remember right early map systems used to give a bit of trouble when changing large amounts of altitude.

[JrZook]

i'm a little rough on th details, hopefully someone wil fill in the details soon.

MAF generally also has air temp sensor built into it as well. it gives a much more accurate measure of the amount of air going into the motor.
MAP is a bit crude in comparison. they only measure pressure. also i think (depending one application etc) they are not very accurate at one end of the scale ie read high boost pressure fine but poor on low boost. ecu uses pressure reading and intake air temps to estimate what the mass of air flow is.

ecu also has altitude sensor. if i remember right early map systems used to give a bit of trouble when changing large amounts of altitude.

Its the other way around.

MAP sensors require an IAT (intake air temp). This is used in combination with the MAP sensor to calculate the density of the air. Hence its an indirect way of measuring way the incoming airflow. MAP works greater for lower throttle applications due to the greater change in intake vacuum vs throttle opening.

MAF directly measure the air flow (volume) the engine is consuming. There is no need for an air temp sensor because the air flow is directly related to temperature and pressure. So it can determine air flow more accurately than MAP.

In terms of the altitude stuff, early or basic MAP systems only had a single pressure sensor which would take a reading when you initially started the engine of the barometric pressure, uses for a compensation factor in the fueling algorithm. Once running it will just measure intake pressure. So a continual run upto a rather high altitude will have fueling errors due to the barometric correction pressure reading done at the bottom.

MAF's impede the intake system and can be rater bulky, fragile and expensive tho they accurately measure the air flow directly thus self compensating for temp and pressure changes (altitude).

MAP are relatively cheap and robust but will need extra sensors such as an IAT and also a barometric pressure sensor for altitude correction.

My 2 c

Dan

Dan

[Kitika]

MAF sensors don't like dust or oil either. All the LS series motors can be tuned without the MAF at all and work quite well. HSV's came out with out the maf with a better tune whereas all the standard commodore v8's came out with the maf but with the exact same motor. They all have a MAP sensor aswell.
What motor are you referring too?

[BadMav]

The early ford efi 250's (XE and XF EEC IV) had a rather restrictive flap style MAF which also housed an air temp sensor. It was an easy way to enrichen the mixture for some more poke, just unplug it. I got just over 191hp at the wheels ONLY by playing with the flow meter spring and adding a custom cold air intake while still getting around 9L/100kms

Then I wised up and bombed a 351 and stuck that in.

[n95cc]

thanks for u share

[PGS 4WD]

MAF sensors don't like dust or oil either. All the LS series motors can be tuned without the MAF at all and work quite well. HSV's came out with out the maf with a better tune whereas all the standard commodore v8's came out with the maf but with the exact same motor. They all have a MAP sensor aswell.
What motor are you referring too?

I wouldn't exactly agree with this, the fuel transients do not work with an E38 ecu with the MAF removed that can lead to fuelling issues related to accelerator pump activation. The large MAF's in these are generally best left in. Only the LS1 ecu was used by HSV without a MAF.

Joel

[JrZook]

I wouldn't exactly agree with this, the fuel transients do not work with an E38 ecu with the MAF removed that can lead to fuelling issues related to accelerator pump activation. The large MAF's in these are generally best left in. Only the LS1 ecu was used by HSV without a MAF.

Joel

So this E38 ecu uses the MAF for fuel enrichment on acceleration? I thought it would have uses the TPS to determine acceleration enrichment.

Dan

[phat-customs]

So a continual run upto a rather high altitude will have fueling errors due to the barometric correction pressure reading done at the bottom.

Shouldnt this be trimmed by the O2 sensor???

[PGS 4WD]

I wouldn't exactly agree with this, the fuel transients do not work with an E38 ecu with the MAF removed that can lead to fuelling issues related to accelerator pump activation. The large MAF's in these are generally best left in. Only the LS1 ecu was used by HSV without a MAF.

Joel

So this E38 ecu uses the MAF for fuel enrichment on acceleration? I thought it would have uses the TPS to determine acceleration enrichment.

Dan

No MAF is much more accurate, when you slam open the throttle there is very little flow initialy and it then ramps up, TPS enrichment would cause an unnecessary rich condition that would not pass emissions.

Joel