Here’s a good map sensor for Arduino pressure projects. Tunerwizard has taken the time to figure out and create a 4 bar map sensor to help the auto DIY enthusiast out. This map sensor was made for Hondas but it can be used on any engine. Just tap into the manifold vacuum and tee it off to this map sensor. The hookup is very simple. It required 5 volts and ground. The third pin is the output voltage. Take a look at the map and you’ll figure out how to convert the voltage output into something meaningful like PSI.

Key Features:

• OEM Fitment and quality
• MAP sensor requires reprogramming of the ECU to function.
• Linear scale for perfect scaling and drive-ability at all boost and vacuum levels.  Compatible with all aftermarket engine management systems.  Can operate between 40-260*F.
• Read up to 43.3 psi

Here’s the output of the value from the map sensor to its corresponding value in Arduino along to what we need it to display in terms of mbar. The sensor outputs a voltage between .82 volts to 5 volts. Once we feed that to the analog input of A1, the A/D converter will convert it to a number between 0-1023. We then need this to 0-1023 number to correlate to 500-4000mbar or -7.4481-43.3152 psig. To do that, we can use the MAP function however it’s not as precise because the MAP function only outputs whole numbers. Note:

To make this work, we’ll need to use the formula below.  Pin A1 will be our sensor voltage input.

Long adconvert = (A1 – in_min)*(out_max – out_min)/(in_max – in_min)+out_min;

Long adconvert=(A1-0.82)*(1023-167.77)/(5-0.82)+167.77;
Long psia = (adconvert-167.77)*(58.0152-7.2519)/(1023-167.77)+7.2519;

To get psig, we add this line of code assuming we are at sea level.

Long psig = psia – 14.7;

Get the map sensor at a discount with this code: arduinomap

Get the map sensor here: http://tunerwizard.com