MAP vs AFM

[RomanV]

Hi there. Every now and then I hear of someone running an new ECU in their car, and converting to a MAP sensor from the AFM.

Why is this?
It makes sense if you are running exposed individual throttles or something like that, but why else would you do this?

If AFM is so crappy, why do quite a few performance cars come with it from the factory?

Or is it just easier to tune perhaps?

[Bazda]

mines afm, I luv it

[FLAWLES]

mines afm, I luv it

hahaha

mines map i love it to

dont now tho ask vvega he solves a lot of techo probs on this board

[Bazda]

mines afm, I luv it

hahaha

mines map i love it to

dont now tho ask vvega he solves a lot of techo probs on this board

nah sorry mines beta

[3T-Rona]

apparantly AFM is better, because with MAP the ecu is setup so that manifold air pressure is gauged compared to atmospheric pressure i.e is atmospherc pressure is 1psi and ur MAP was 3psi the ecu knows ur accelerating at 14% or wot ever, but when they tune ur car the atmospheric pressure is set to where u are in relevance to sea level, so if mines tuned in Tauranga and i blitz it over the kaimais the atmospheric pressure is gonna be different to that set in my ecu. the AFM just gauges how much airs going in so it works were ever.
apparantly map is easier and cheaper to setup and less restrictive for intake....... a lil of this and a lil of that all gd in the end
sorry if i rambled

[sergei]

I disagree, MAP measures pressure difference between manifold and its own vacuum chamber (close to absolute vacuum)...
here: http://www.autoshop101.com/forms/h24.pdf scroll down to page 11...

[matt dunn]

AFM is more accurate for manufacture's as they need their car to be 100% driveable in all conditions.

Map is not accurate enough between 12.345psi and say 12.765 psi or what ever whereas AFM wil see a larger difference in airflow increase.

[Akane]

as said before, AFM is more accurate than MAP, and will suit all driving conditions as it measure the air going in, not just amount of pressure in the manifold.

[fivebob]

AFM is not necessarily more accurate than MAP, but it is self adjusting. So if you change the Volumentric efficiency of the engine (change the cams/Exhaust etc) then the AFM equipped engine would not need to be re-tuned, whereas a MAP equipped end may require adjusting.

Most aftermarket ECU's can be made to work with either system, but AFM's often run out of calibration if you greatly increase the airflow, and sometimes they also create a flow restriction, so they are often discarded and replaced with TPS/RPM (mainly for NA engines) or MAP/RPM (forced induction) tuning maps.

[3T-Rona]

I disagree, MAP measures pressure difference between manifold and its own vacuum chamber (close to absolute vacuum)...
here: http://www.autoshop101.com/forms/h24.pdf scroll down to page 11...

the info i posted is wot i was told by one of the guys at PF automotive more or less in my own words, im not sure about OEM MAP sensors but if u look at a link MAP sensor or any other Aftermarket MAP sensor (within reason) theres no lil chamber to gauge it against, so its gauging against wot is set as barometric pressure (sea level) by the tuner.
correct me if im wrong as im just goin off wot i was told, or wot i understand to be wot i was told.

[sergei]

I think most of map sensors have very similar design...
the thing is that outside pressure will bias plenium pressure, that's why some cars have extra pressure sensor for outside pressure, to compensate... thats why cars without this compensation will have to be retuned for different altitude

[3T-Rona]

I think most of map sensors have very similar design...
the thing is that outside pressure will bias plenium pressure, that's why some cars have extra pressure sensor for outside pressure, to compensate... thats why cars without this compensation will have to be retuned for different altitude

so running a link or wotever it wld have to be retuned for different barometric pressures

[boy_with_a_new_toy]

depends with map sensors if they need re-tuning becoz some come with a barometic pressure sensor which compensates for the change in air density, personally i like map sensors, afm restrict air flow way 2 much and are a lil pain in the ass when changing induction piping etc when they hav 2 be mooved. not all afm are that good at self adjusting because not all have an air temp sensor to adjust for air density....

[Akane]

Yeah, but when you get kiddies in their 323's making 200hp with their mate's homebrew t3/t4 setup, and complaining about how restrict their AFM is, is kinda annoying.

[3T-Rona]

Yeah, but when you get kiddies in their 323's making 200hp with their mate's homebrew t3/t4 setup, and complaining about how restrict their AFM is, is kinda annoying.

this ammuses me