Vacuum guage and computer don't match.

peasly23 · Post by **peasly23** » Sun Jun 13, 2010 11:23 am

Really I've had this problem from the beginning. I have brand new Aeromotive vacuum/boost guage and my vacuum never seems to match my computer.

Details:
EBay purchased Motorola 3-bar MAP sensor. (3 prongs connected to stock map sensor wires) I can't remember what is wired where.
Stock MAP sensor removed.
Gauge & MAP sensor are connected right next to eachother on a vacuum manifold connected to the brake booster line.
Everything is air tight.
The guage reads only slightly lower than the computer. (ie: guage says -25" vacuum and computer says -21" vacuum.

newsoltsc · Post by **newsoltsc** » Sun Jun 13, 2010 1:37 pm

I think it all depends on where you are tapping your vacuum from.

Id go by the MAP sensor on the ECU rather than the gauge.

My gauge reads -20inHG to -22inHG at idle. But my MAP sensor reads -18inHG to -20inHG at idle.

I trust the MAP reading over the gauge. I doubt the gauge will read the exact amount of vacuum.

This is in all electronic/mechanical gauges Ive seen anyways. They are always off by 1-2"

Post by **Spunkster** » Mon Jun 14, 2010 9:57 am

Put the stock map sensor back and compare to that.

peasly23 · Post by **peasly23** » Mon Jun 14, 2010 10:04 am

While I appreciate the good suggestion, I cut the stock harness off and soldered the wires to the new one. Any other ideas?

Post by **Spunkster** » Mon Jun 14, 2010 10:53 am

Desolder it and put it back to stock.

landspeed · Post by **landspeed** » Thu Jun 17, 2010 9:35 am

I have an Autometer electronic with it's own MAP and it reads off of the stock map vacuum by 1-2 in my rsx as well