Torque, engine power and boost pressure added

A few days ago we launched the updated OBD Auto Doctor software. This time our main focus was in calculated performance parameters such as Engine Torque, Engine Horsepower and Turbo Boost Pressure.

You can now measure the performance of your car by monitoring these new sensors in real time. Read further to get insight into the details.

Torque, Engine Power and Boost Pressure
Engine performance sensors chart from the csv data, saved using Google Sheets

Engine Power or Horsepower

Engine power (or horsepower) can be estimated quite well using vehicle speed and its change over very short period of time. The total weight of the vehicle is also needed for valid results.

OBD Auto Doctor measures the engine power at the wheels. This is not the same as at the flywheel. Therefore, if the vehicle speed doesn’t change, the power will show zero. The horsepower will be greater than zero only when the vehicle is accelerating.

The software will also take power loss due to drag into consideration when calculating the power. An average drag coefficient and vehicle frontal area are used.

You can set the vehicle weight in the app settings. To get the most accurate weight, drive your car to a weightbridge. You could also estimate the total weight by using manufacturer defined weight added with the passenger weight, fuel weight plus any extra weight included in the vehile.


Torque is calculated from the engine power and RPM. With these two pieces of information, the torque can be estimated quite accurately. Torque is measured at the wheels just like the engine power.

Since torque is using engine power for the calculation, the vehicle weight is a factor in the calculation. Remember to set the correct weight!

Boost Pressure

Boost pressure value yields from the intake manifold absolute pressure. Barometric pressure is also taken into consideration. Now, the vehicle is required to support MAP (manifold absolute pressure) in order for the boost pressure to appear as supported. Barometric pressure is optional. The default pressure value at sea level is used unless the car provides support for the actual barometric pressure.

Negative pressure values represent vacuum. Positive values are boosted by a turbocharger or supercharger.

Other improvements

Among the new calculated performance parameters, we also added more.

The software has now support for all Mode $06 scaling IDs. The latest OBD2 standard version added 12 new identifiers. OBD Auto Doctor implements now all the new IDs in addition to the old ones.

If you are using the desktop software, download the latest version from the download page. The updated mobile apps can be found from the approriate app stores using your phone.