Reading Boost, MAP Sensor Design Pt. 1

In today’s fast-paced data-driven world, car manufacturers, like Honda, are trying to squeeze out every ounce of efficiency that they can. This means modern cars like the tenth generation Civic SI have loads of sensors to collect all sorts of data. Today we will be breaking down the MAP sensor also known as the Manifold Absolute Pressure sensor.

A MAP sensor measures the instantaneous absolute pressure in the manifold its placed in and then relays that data to the car’s Engine Control Unit (ECU) or (PCM). The ECU takes that data as well as data from other sensors and determines certain outputs like ignition and injector timing among others. This means the MAP sensor is a vital component whose data will affect the overall performance of a car and also limits tuning capability when you push outside the bounds of the OEM sensor.

OEM MAP sensor found in 2016+ Honda Civic Turbo

Now let's talk about the tenth gen Civic specifically. Your Civic has 2 MAP sensors; however, one sensor is more common in most applications. One of your sensors is located in the usual location, the intake manifold. The other is located in the cold side charge pipe that connects your throttle body to your Front Mount Intercooler (FMIC).

The sensor in Orange to highlight its location

The MAP sensor in the charge pipe allows the ECU to more accurately measure turbocharger pressure as it exits the FMIC before any losses occur through the throttle body. This makes tuning and reaching the turbocharger target pressure much easier. Having a sensor in the intake manifold allows the ECU to know the pressure right before it enters the cylinder and allows for fine tuning of ignition timing and other ECU outputs. Comparing both sensors allows the ECU to determine pressure loss through the throttle body which helps increase efficiency.   

Alright, let’s get nerdy. A common misconception is that the MAP sensor is the same as a boost sensor. A MAP sensor measures absolute pressure whereas most boost sensors measures gauge pressure relative to atmospheric pressure. This means a 3 Bar MAP sensor will read 1.01325 Bar ~ 1 atmosphere ~ 14.7 PSI absolute while a boost sensor will read 0. This means the OEM 3 Bar MAP sensor can measure up to 43.51 PSI absolute. The boost pressure that you see on your dash is gauge pressure so when your dash says 0 PSI your map sensor more or less measures 14.7 PSI.

This means the maximum “boost” that your OEM MAP sensor will support is ~28 PSI. If you wish to push past around 28 PSI, as we at 27WON do, then you must ditch the OEM MAP sensor and upgrade to an aftermarket 4 Bar MAP sensor. 

Due to our thirst for boost we’ve hit this “weak” point in the OEM system. We have started exploring producing our own 4 bar MAP sensor. A MAP sensor that will provide the reliability and peace of mind you have come to know from 27WON products. A MAP sensor with a little POP, maybe even orange…

Thank you for joining us and letting me share some knowledge about MAP sensors. Be sure to come back to keep up on all we are doing here at 27WON.

Let us know in the comments if you are interested in seeing a MAP sensor from 27WON. 
-Austin