next topic »

[on:]

Hey everyone, long time lurker, first time poster.

I'm putting together a car computer and one of the functions I need it to measure is the pressure of the turbo boost. My uneducated idea is that I run a tube from the vacuum hoses into the car, connect it with a pressure sensor and use an Arduino set up to translate the pressure into something a car computer will understand. The computer then displays the boost reading (probably in numbers as that's easier).

Some pre-answers... firstly, the car doesn't currently have a boost gauge, otherwise I'd just get the info from the ECU. Secondly, the boost, in theory could be anywhere between -30 to +30 psi.I'm happy (and would prefer) the resultant reading to be in psi.

I feel confident that I can blunder through this project, but I have very limited electronics skills and haven't yet learned the programming side, but I keep hearing that Arduino is easy.

Any advice would be fantastic, especially on the hardware side (sensor and Arduino set up especially).

Also, to reiterate (so mods don't move this) the key queries I have revolve around the sensor that I plug the tube from the vacuum tube into. I'm not really sure which one to get or how to read from it.

Thanks!

[Reply #1 on:]

Couple of things.

Most stock turbo'd cars "calculate" the boost reading based on several sensors and do not read it exclusively from a MAP sensor. DSMs (eclipse/talon/laser), for example, do that.

Second, pick up a 3bar map sensor from a turbo car at a junkyard (or buy new, but they can get expensive).

Reading from a 3bar map sensor is pretty straight forward. 3pins, positive, negative, and the signal pin. It's been awhile since I did something like this so I don't remember the format of the signal pin. Every electronic boost gauge (and boost controller) that I've ever seen/owned reads off of a 3bar map. What kind of car are we talking about here?

[Reply #2 on:]

Thanks for the reply!

The car I'm talking about is a Saab 93 (99 model). The model I have came with a "low pressure turbo" which just meant the boost pressure was capped at around 8 psi. I have put in a boost controller and tuned the ECU so that I get the full range of the turbo.

Unfortunately, that means no gauge.

I'm putting together a car pc with an Arduino attachment reads data from the ECU through the ODBII connection and I also will need the input from the pressure sensor. 3 bar does sound about right, though.

[Reply #3 on:]

Depending on how you would like to do this (tube to gauge like a normal boost gauge or tube to a sensor under bonnet with wiring back to gauge) there are a couple of options.

I laid out a circular pcb at one point with 7seg displays in the middle and leds around the outside so it would have a programmable "redline" so to speak. My design was aimed at the gauge being used in a string and a button being pressed on an individual gauge to allow you to change its readout - so I didn't have any sensors onboard any gauge - that was all at the main controller. I also had two different sizes (my project was to build a whole dash worth of gauges along with indicator lights, warning lights, odo, trip etc.

4 bar map sensor with baro corrections if you want to have the tube run to the gauge
http://www.diyautotune.com/catalog/mapdaddy-bar-map-sensor-with-barometric-correction-p-117.html

The same place has external 3 bar map sensors for about the same money.