Hi guys,

I know there are some electronics experts on this forum. Something that I have always wanted to do was to splice into the 5v signal coming off of a GM MAP sensor, and display it as boost pressure or vacuum on a needle or LED guage. If I use a needle guage, I would print a face with the markings for the boost/vacuum levels. Or is there a way to rewire the stock GM "boost" guage so that it reads from the sensor instead of a best guess from the ECU?

Where should I start? Is there such a thing as a how-to for this or any good referrences?

Here is a chart of the voltage vs pressure reading:

LED gauge would be pretty easy... A needle gauge a bit harder but not impossible.

For the LED gauge, basically you'd need a Bargraph LED driver.

http://www.evconvert.com/ar...raph-battery-monitor

dont they sell guages which read & display the MAP values?
standard vacuum/boost gauge, isnt it?

quote Originally posted by Pyrthian: dont they sell guages which read & display the MAP values? standard vacuum/boost gauge, isnt it?

There are vacuum/boost guages out there but you have to either run a vacuum hose to them or they come with their own sensors. I just want to splice into the existing sensor and see exactly what the ECU is seeing without having to plug in my laptop to the truck.

quote Originally posted by Doug85GT: Thanks. That definately points me in the right direction.

If you look at the datasheet for the 3914, it's pretty easy to use. Basically you just adjust the voltages on a couple pins to tell the chip where you want "low" voltage and "high" voltage on the bargraph.

http://www.national.com/ds/LM/LM3914.pdf

and it's a constant current driver, so you can run blue, violet, white, red, green, etc... LEDs. (Which I think is pretty cool)

Edit: and you can cascade them if 10 LEDs isn't enough resolution.

[This message has been edited by ryan.hess (edited 05-27-2010).]