How to get your turbocharged engine boost pressure with iOBD2?

Do you know that if your car has a turbocharged engine, you can get turbo boost pressure with iOBD2 although there is no a boost gauge on iOBD2? It is easy. Simply read the MAP (Manifold Absolute Pressure) value, and then subtract 100Kpa and you will get the boost pressure.

I didn’t get this idea until one of our customers sent me a message. Here is the story.

A few days ago, one of our customers sent me a message on our company Facebook page saying he could not find boost gauge on iOBD2 as he mainly wanted to know the boost pressure of his 2013 Hyundai Veloster Turbo. I said sorry to him that iOBD2 app was designed according to the generic OBD II specification and a support for boost gauge was not demanded in the specification.  The next day he said his Veloster Turbo hit 202 KPa (which is too high) and wanted to confirm if there was problem with the app or his car. This time I was confused. How did he get the 202Kpa as the app did not have a boost pressure gauge? He told me that he got a max MAP value of 221Kpa but had been subtracting 100Kpa, so that made a boost pressure of 121Kpa which is normal. Now I understood that the 202Kpa he got was a MAP value but not a boost pressure value.

Yet I still want to know the theory behind it and the following was what I found from volvoforums.com.

Keep your car healthy with your iPhone

Normally you use iPhone to make a call, send a message, watch a video, play a game, or take a photo. But how about use your iPhone to monitor the health of your car?  Whether you realize it or not, to keep your car healthy, you should install an OBD II app in your phone and start to monitor how your car is doing. There are both free and charged OBD II apps in the app store for you to choose from.

Before you can take the next step, you have to prepare an OBD II adapter for connecting your iPhone with your car’s on-board computer. Make sure the adapter supports both your car and the app.

When everything is ready, plug the adapter into the 16 pinout OBD II port on your car. It is usually under the steering wheel. Connect your iPhone with the adapter according to the user manual.

Now you can get access to the whole data of your car’s on-board computer, such as engine coolant temperature, fuel economy, intake air temperature, manifold absolute pressure, torque, horse power and so on. Monitoring those data will help you sense a potential problem before it gets worse.

How to choose the right OBD-II scan tool for your car?

Figure out what functions do you need from the tool.
Do you just need to read the trouble codes or erase the codes? Do you want to close the check engine light when it is on? Or do you want to access to more advanced data besides the engine data? So choose the tool that best fits your need.

Set your budget for the tool.
There are many kinds of OBD-II scan tool averaging 20$ to 200$ on the market. Generally the more functions the tool has, the more expensive the price is. 

Make sure your car model is supported by the tool.
Find out the manufacture year and model of your car and make sure it is OBD-II/EOBD compliant. Then choose one that is compatible with your car. A normal OBD-II scan tool should support cars that are OBD-II/EOBD compliant. 

Confirm this before you buy from the seller. 

Find the most cost-effective OBD-II scan tool on xtooltechstore.

What is OBD, what OBD can do?

Most car owners have heard of OBD port but few know what it is and what it can do. They just see at the repair shop a mechanic diagnose the car by plugging a scan tool into the port, then the trouble codes are erased and the cleaned air damper stops a warning. However, the OBD port is not as mysterious as imagined. Car owners can become car geeks by knowing how to use it.

What is OBD?

OBD stands for On Board Diagnostics. When the car is running, it monitors the engine electronic control system and other electronic control modules. If there is something unusual, it will detect what the trouble is and store the DTC (Diagnostic Trouble Code) on the ECU (Electronic Control Unit). The DTC helps for car repair and maintenance. A mechanic can quickly locate the problem by reading the code with a scan tool, saving time for a repair.

The OBD port normally locates under the steering wheel, near the place of driver’s knee. Its actual position may differ in car models, but overall it is almost the same position.