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Torque » Torque OBD ECU Scanner » Torque Discussion / Ideas » Boost Pressure

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Author Topic: Boost Pressure
userM
Member
Posts: 96
Post Boost Pressure
on: June 6, 2017 (GMT)

Does anybody knows how accurate are the figures of boost pressure?

My car has a map sensor and a barometer one (at least I think so since I am getting figures for barometric pressure)
Capp777
Member
Posts: 2993
Post Re: Boost Pressure
on: June 6, 2017 (GMT)

Needless to say boost is only as accurate
as your sensors used. There is a standard
OBD pid for MAP [0B] so its equation is defined.

Your baro reading can come from several
places when using Baro() function…

Your vehicle [33].
Your phone’s barometer if available.
If neither baro reading is available I believe
Torque will use a default “14.6” psi.

There is a maximum boost the standard OBD
MAP pressure can measure (~22.3 psi).

Diesel trucks tend to exceed this limit so vehicles capable of
producing a lot of boost will need a different
pid to measure above that limit.

Your boost reading should read near zero with
KOEO at sea level. If you live in a high altitude
location there is a vehicle profile setting that
will need to be adjusted to achieve zero.
userM
Member
Posts: 96
Post Re: Boost Pressure
on: June 6, 2017 (GMT)

assuming that the sensor is accurate
and the cars barometer too.

the results would be accurate
or still would be wrong
just because the readings comes from obd2 port?

Me and a friend have a debate
regarding the boost numbers we are getting
and since we don’t know which are the default-stock
we have stuck :)

the car is a BMW F20 116i (2013 year model turbo) so I think that the sensors are accurate because ecu needs the numbers for its calculations..
Capp777
Member
Posts: 2993
Post Re: Boost Pressure
on: June 6, 2017 (GMT)

You didn’t say if you are getting near zero with
KOEO. If so I would believe its accurate assuming
its below the 22.3 psi limit. (assuming your MAP
and baro are accurate).

Boost is simply MAP minus Baro which is affected
by altitude.

If your newer vehicle supports it the following
thread may be of interest…

https://torque-bhp.com/forums/?wpforumaction=viewtopic&t=8870.0
user_M
Member
Posts: 20
Post Re: Boost Pressure
on: June 6, 2017 (GMT)

I did not mention it because I don’t know how to measure it. )
Just now I saw that it means KeyOnEngineOff but still don’t know how to measure it. If you know how, you have time please elaborate
Capp777
Member
Posts: 2993
Post Re: Boost Pressure
on: June 6, 2017 (GMT)

Add the turbo boost and vacuum
gauge to your realtime dashboard.

While connected to your vehicle with
KOEO…

See what your boost is reading with
only atmospheric conditions since
your engine is not running.

Should read 14.7 (MAP) – 14.7 (Baro
at sea level) which equals zero.
userM
Member
Posts: 96
Post Re: Boost Pressure
on: June 7, 2017 (GMT)

so yes it reads 0
please see photo also

https://ibb.co/dboETF

Thanks
user_M
Member
Posts: 20
Post Re: Boost Pressure
on: June 7, 2017 (GMT)

So can I assume that figures are correct?
Capp777
Member
Posts: 2993
Post Re: Boost Pressure
on: June 7, 2017 (GMT)

Based on the assumption your MAP and
Baro are accurate and match at atmospheric
conditions… assume away in my opinion :)
userM
Member
Posts: 96
Post Re: Boost Pressure
on: June 8, 2017 (GMT)

I will take it as a yes :)
The good thing is that I did found what is the stock boost and I can tell that torque pro is accurate
Thanks
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