I did a search but didn't see any place where actual MAP voltage versus pressure is given.

Assuming 2.95 volts for 1 atmosphere, that sounds like 200mv per psi, but does anyone know for sure? Is it linear? What is the maximum range of the stock sensor?

Obviously I'm making a boost gauge using the stock MAP sensor. I was surprised to learn the Comptech will go above atmospheric at 2500 rpm, I would have thought it would take higher rpms to produce boost.

 

well, it's allegedly linear.



i do know that it doesn't show 0 volts at any achievable amount of engine vacuum, so this looks about right to me.

i believe the VAFC has a mode which displays MAP voltage (possibly in the setup screen.) anyone here with a vafc could just switch back and forth from the manifold pressure display and the voltage display under constant engine conditions (e.g. idling at 20") and confirm a few points on the curve for you.

 

A factory honda map sensor can read up to around 11.5 psi. Maximum voltage of 5V, and the reading are linear.

 

Thanks for the help. Where do you guys get this kind of information? I'm looking for the same info but for the water temp and oil pressure sensors.

Here's my new boost gauge in action. I used a cheap digital panel meter to measure the voltage across the input and output terminals of the Comptech ESM and adjusted the scaling resistors to read PSI. It's not the greatest, but it works.

Features:

• Low cost - maybe $20 (free for me, I had the stuff laying around)
  
• Easy install, especially since I just taped it to the windshield
  
• No backlighting - can't see it at night
  
• Slow to update - panel meters only update 2-3 times a second

Anyway, it works reasonably well, but so far I've not been able to capture any readings over about 5.5 PSI. Could just be that the capture rate is too slow to read those last fractions of a PSI achieved just before redline.