Arduino Forum

Using Arduino => Sensors => Topic started by: PoppaG on Dec 21, 2011, 03:36 am

Title: Digital Car Boost Gauge project
Post by: PoppaG on Dec 21, 2011, 03:36 am
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!
Title: Re: Digital Car Boost Gauge project
Post by: sharkcus on Dec 30, 2011, 11:04 pm
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?
Title: Re: Digital Car Boost Gauge project
Post by: PoppaG on Jan 07, 2012, 09:35 pm
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.
Title: Re: Digital Car Boost Gauge project
Post by: Delta on Jan 13, 2012, 08:23 am
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.