MAP Sensor ...malfunction?

[cperry]

Hi, with MAP sensor plugged into my skyview ems, my MAP guage is crossed out with a red X. With the power/gnd wires supplying 5v, and plugged in, when I disconnect the signal wire, the red x goes away, and I get a reading between 50-60. Plug the signal wire back in, and red x comes back. Sound like a Pooched sensor?

 

[dynonsupport]

It's a pretty reliable sensor, but it's possible it's failed. My bet would be on a slight mis-wiring though. There's a slight tendency for the A,B,C pins to get connected to the wrong wires. The red X means that it is seeing essentially ground (or something very close to it), and wires going to the wrong place can cause this.

 

[cperry]

Ok, I'll check the wiring (this has been rewired once, its always possible it has been connected incorrectly previously), and with the 5v applied, I'll check the voltage on the center pin with a pressure change, and let you know the results.

Chris

 

[cperry]

So, did some checking. First on the EMS side, if I split the 5v to gnd with two equal resistors onto the gn/rd wire, I get a reading of 31.8inhg. With the gn/rd wire disconnected, I get 8.8inhg, connected to either gnd or 5v, I get the red X. My assumption is this is probably normal, and the EMS is functioning as expected.

On the sensor, with wt/rd connected to C, and A connected to GND, I'm getting 5.05V from B to GND with the air line open to atmosphere. C is 5.06V to GND, and A is 1.6mV to GND.

Disconnected, I'm getting 10.6kohm from A to B, and 6.0kohm from B to C.

Sound normal, or totally out to lunch?
Chris

 

[jakej]

Chris

Do you see the letters, A B C, on the connector and can confirm that the correct coloured wires are in them?

Jake J

 

[dynonsupport]

Here are a couple of points from the measurement (inHg)/Voltage output that you should be seeing:

inHg Volts
48.3 3.9
38.3 3.0
30.6 2.3
25.3 1.9
19.1 1.4
16.6 1.2

So at ambient (30ish inches), you should be seeing 2.something volts.

 

[cperry]

Replacing the MAP sensor resolve the issue. Thanks!