Boost pressure reading on Mazda Hi-Power R2 Engine

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hiej
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Joined: Thu Oct 30, 2014 3:11 pm
Vehicle: 2010 Mazda 3 - 2.2d 136KW

Boost pressure reading on Mazda Hi-Power R2 Engine

Post by hiej » Fri Nov 07, 2014 11:25 am

Hello,

I would like to know if is it possible to read the boost pressure when the values goes over 1.55 bars.

Using the OBD2 standard MAP pid when the pressure exceed the 255 kPa (i think this is a HEX limitation), instead to show 256 kPa is shown 0, instead to show 257 kPa is shown 1, instead to show 256 kPa is shown 0, instead to show 258 kPa is shown 2 and so on.

Using Mazda MAP pid instead when the pressure exceed the 255 kPa, instead to show 256, 257, 258 and so on, the value stiks to 255

On R2 Hi-Power engine (136 KW - 400Nm) doing some experiments I've seen that the intake absolute pressure achieves 270 - 272 kPa.

is there a PID that allow to read the pressure over 2.55 kpa?

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Re: Boost pressure reading on Mazda Hi-Power R2 Engine

Post by FORScan » Sat Nov 08, 2014 7:58 am

Yes, majority of MAP PIDs are 1 byte long and not designed for pressure greater than 255 kPA. Our database has high resolution PIDs for MAP exists for Ford, but we have no infromation if any of them are supported on Mazda. So your options:

1. Use MAP_V (PID that shows voltage). Workshop manual may have conversion table from Volts to pressure (in fact, we can add converter Volt->Pressure for your model if you find such a table)

2. Use some boost PID, for example your PCM should support BOOST_DSD PID (desired boost - value PCM wants to reach). Yes, it is another PID, but in some cases it may be helpful/enough, as if the turbocharger is OK the BOOST_DSD and MAP should match.

3. Your model should have PCM of the last generation. Our experience with Ford models indicates that for such PCM some amount of PIDs is missing in our database. So it does make sense to try to scan module for these missing PIDs. If you are interested, please contact us by email.

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hiej
Posts: 24
Joined: Thu Oct 30, 2014 3:11 pm
Vehicle: 2010 Mazda 3 - 2.2d 136KW

Re: Boost pressure reading on Mazda Hi-Power R2 Engine

Post by hiej » Sat Nov 08, 2014 12:06 pm

On workshop manual there's no a conversion table (maybe I need to check better :) )

I've created an empirical formula to use with obdlik android app to convert volt readings in bar: (((((A*256)+B)/1000)*90)-[33])/100 and it seems quite correct.

Same thing I've done reading dsd boost: (((A*256)+B)/64)/100

Note that I've used "/90" and "/64" divisors to match the real pressure read in kpa by map sensor, but im not sure that these equation are ok.

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Re: Boost pressure reading on Mazda Hi-Power R2 Engine

Post by FORScan » Mon Nov 10, 2014 2:25 am

PM sent

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