AFM to MAP conversion, and temperature compensation~?

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AFM to MAP conversion, and temperature compensation~?

Postby erolit » Thu Aug 25, 2005 10:34 pm

Hey,

I've just been thinking, most MAP sensor based airflow systems have manfold temperature sensors to compensate for the change in air density throughout the wide temperature range of the compressed intake air.

Most of the alltrac AFM to MAP converstions people seem to be doing these days (SMT6/7, circuit board based ones) dont have any compensation for air temperature short of the pre-intercooler airflow temperature sensor (which most people get rid of when they switch to MAP anyway). When manifold temperatures can swing 50-60 degrees on/off boost you are talking almost 20% difference in air density...?

How is this compensated for? Is it that there is a different pressure at zero degrees vs 80 degrees, and the MAP sensor can detect that? If so, what are the MAT sensors for in cars such as the ST205?

(I'm about to attempt MAP conversion using an old IFT fuel computer by PerfectPower, and i am wondering how i need to go about modifying the signal for temperature.)

Thanks guys,

Elliott
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Postby OlyST185 » Fri Aug 26, 2005 2:57 am

if you want my advise, if you want the perfect mixture first you'll need wideband o2 sensor and a standalone, the to trick to convert AFM to MAP signal has a problem even if you find a way to make the IAT available for the computer:
The afm reads the air just beside the air filter, the MAP reads it in the intake manifold, so thier a difference delay between the signal so theres no way you can have a 100% effective air/fuel mixture, by the way it would be close, like 80-90%.
my 2 cents.
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Postby ChrisD » Fri Aug 26, 2005 3:14 pm

It shouldnt vary that much...but the ECU does do corrections, you just need to install the intake temp sensor in your system, which is found in the AFM.
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Postby erolit » Fri Aug 26, 2005 5:50 pm

Well hopefully it should be all good for me to attempt the conversion, because before i bought the IFT (a realllly oldschool perfectpower tuning device, 2 fuel maps with corrections for boost and intake temp, 1 ignition map) i bought an ST205 ECU and MAT sensor. I installed the sensor just pre-throttle body and its still there, so i will just use that for temperature correction.

I've got my wideband, 3 channel datalogger and the fuel computer - this sunday i'll give the afm>map conversion a shot. I'll post all the results (i can log MAP and AFM side by side at high resolution), as well as the fuel maps i end up with (the IFT has an almost identical fuel map configuration to the SMT6/7 - that is a 7x16 tuning map with a 1x16 correction map for boost/temperature)

Elliott
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Coolingmist water injection
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Postby BriinumsBo » Mon Apr 06, 2009 6:20 am

erolit wrote:Well hopefully it should be all good for me to attempt the conversion, because before i bought the IFT (a realllly oldschool perfectpower tuning device, 2 fuel maps with corrections for boost and intake temp, 1 ignition map) i bought an ST205 ECU and MAT sensor. I installed the sensor just pre-throttle body and its still there, so i will just use that for temperature correction.

I've got my wideband, 3 channel datalogger and the fuel computer - this sunday i'll give the afm>map conversion a shot. I'll post all the results (i can log MAP and AFM side by side at high resolution), as well as the fuel maps i end up with (the IFT has an almost identical fuel map configuration to the SMT6/7 - that is a 7x16 tuning map with a 1x16 correction map for boost/temperature)

Elliott


4 years later. results? :D
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Postby built2run » Sat Apr 11, 2009 8:01 am

lol the supra guys have the way to do it (7mge ma70 supra) the box costs 400bucks but for a straight accross change over it would be simple to do and cost about 100 bucks but i still need to make a simple board to do this but i just don't know the hardware i'll soon find out and make one for me and if its worth it i'll possibly do a write up

btw it will net you very little gains but it will make the engine bay look cleaner and less cluttered.
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Postby Simba » Sat Apr 11, 2009 2:28 pm

If you're contemplating converting to a map setup without a system that can read and adjust for air temperature, quite simply: DON'T.

If you want to do it, do it properly with a standalone EMS or good piggyback that can do it properly like the MAP-ECU.

Lots of fast, loud things.
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Postby built2run » Sat Apr 11, 2009 11:54 pm

it will have a IAT sensor
"straight lines r 4 fast cars, turns r 4 fast drivers" Colin McRae.
ST165, black: parted and gone
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ST165, white: sold to friend
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Postby RafaCalde » Sun Apr 12, 2009 4:21 am

what piggy-back systems are able to do it?
Rafa

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Postby built2run » Sun Apr 12, 2009 5:56 am

aem fic is one and the other is maft there are more just look around
"straight lines r 4 fast cars, turns r 4 fast drivers" Colin McRae.
ST165, black: parted and gone
ST165, white: rear ended by ass hat
ST165, white: sold to friend
ST185, black: current project, "The Kraken"
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Postby built2run » Wed Apr 15, 2009 5:42 pm

in a little over a week i will be prototyping a map conversion box that has that is a direct conversion/no adjustments. later it will be retro fitted to a hot wire MAF like those on newer toyotas. let me know your oppinions.
"straight lines r 4 fast cars, turns r 4 fast drivers" Colin McRae.
ST165, black: parted and gone
ST165, white: rear ended by ass hat
ST165, white: sold to friend
ST185, black: current project, "The Kraken"
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Postby BriinumsBo » Wed Apr 15, 2009 7:12 pm

are you doing it on some microprocessor like Arduino board?
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Postby built2run » Wed Apr 15, 2009 8:14 pm

kind of, this first one will be a prototype so it will be pretty crude but it will still be in a box of some sort to keep it protected just not sure if i will mount it in the cabin somwhere or in the engine bay.

i guess to better answer you..... maybe lol
"straight lines r 4 fast cars, turns r 4 fast drivers" Colin McRae.
ST165, black: parted and gone
ST165, white: rear ended by ass hat
ST165, white: sold to friend
ST185, black: current project, "The Kraken"
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Postby BriinumsBo » Tue Apr 21, 2009 6:53 am

is there anyone on the board running AEM FIC un 2gen ?
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