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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » MAP sensor limit to 255 kpa? (FF in hex)

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Author Topic: MAP sensor limit to 255 kpa? (FF in hex)
Hiej
Member
Posts: 173
Post MAP sensor limit to 255 kpa? (FF in hex)
on: June 7, 2012 (GMT)

Hi Ian,

there’s a limit on the max value readable on intake manifold pressure?

I’ve done several test with my car and the max value I get is 255 kpa (that corresponds to FF in hex).

So my question is: this 255 (FF) is the limit of the app or could be the limit of MAP the sensor in my car?

If 255 is the limit of Torque app., could you add the possibility to read higher values?

– – – – – – – – – – – – – – – – – – – – – – –
2010 Mazda 2.2d – 185
OBDLink MX – SGS7
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piemmm
Administrator
Posts: 6629
Post Re: MAP sensor limit to 255 kpa? (FF in hex)
on: June 7, 2012 (GMT)

Hi!

The FF limit is imposed by the J1979 specification, as written by the SAE – it’s not a limitation of the app per-se, but the actual protocol that the ECU uses and the specification that it is written to

If your vehicle has MAF as well as MAP, then select ‘MAF’ in the ‘Boost calculation method’ setting (in settings->OBD2 adapter settings) which will switch the calculation to use the MAF sensor instead (which can read higher flow rates)

Make sure you have the engine displacement set correctly in the vehicle profile though, and that you have ‘faster communication’ enabled in the OBD2 settings
Hiej
Member
Posts: 173
Post Re: MAP sensor limit to 255 kpa? (FF in hex)
on: June 7, 2012 (GMT)

thanks ian.

in effect using maf mode I can read pressures till 1,9 BAR (i think this is the right value for my engine).

a question: what differences there’s between MAF and ALT mode?

On my car if I use Alt mode I get the same values of Maf mode, but in alt mode the needle moves smootly

– – – – – – – – – – – – – – – – – – – – – – –
2010 Mazda 2.2d – 185
OBDLink MX – SGS7
– – – – – – – – – – – – – – – – – – – – – – –
Hiej
Member
Posts: 173
Post Re: MAP sensor limit to 255 kpa? (FF in hex)
on: June 11, 2012 (GMT)

Ian,

reading across the forum, I’ve noticed that to a have a reliable reading of boost value throught MAF sensor is important to set the corect displacement and adjust VE.

So to find correct VE it’s no easy it can take many time and many tests.

My idea is to crate a custom pid to read boost throught MAF sensor, and put the gauge within another gauge that reads the boost throught MAP sensor (stadard pid ff1202)…

my problem is how to generate the right equation for the custom PID… could you help me?

– – – – – – – – – – – – – – – – – – – – – – –
2010 Mazda 2.2d – 185
OBDLink MX – SGS7
– – – – – – – – – – – – – – – – – – – – – – –
piemmm
Administrator
Posts: 6629
Post Re: MAP sensor limit to 255 kpa? (FF in hex)
on: June 11, 2012 (GMT)

Hi!

To get the ‘ff1202’ value, enclose it in square brackets in the equation editor, eg:

Equation: [ff1202]+400

(or something like that) :-)
Hiej
Member
Posts: 173
Post Re: MAP sensor limit to 255 kpa? (FF in hex)
on: June 11, 2012 (GMT)

uh! maybe a miss understand :-)

I need equation to calculate boost from MAF.

in any case I’ve found another way: I create a custom pid to get boost starting from Map pressure (it’ more easy) and then I compare it with the values retrieved by Torque using Maf calculation mode.

I think that in this way, playing with the VE I will be able to find the right VE value to use to have same boost readings in MAP and MAF mode.

– – – – – – – – – – – – – – – – – – – – – – –
2010 Mazda 2.2d – 185
OBDLink MX – SGS7
– – – – – – – – – – – – – – – – – – – – – – –
Jakalfree
Member
Posts: 2
Post Re: MAP sensor limit to 255 kpa? (FF in hex)
on: December 14, 2019 (GMT)

Map ok
Maf ok
But…

ALT metod what is it?

Bmw lovers
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