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D-180 Manifold Pressure Issue

Toobuilder

Toobuilder

Well Known Member
I have recently installed a D-180 and cant seem to get my MP indication to function properly. On initial power up, the needle will slowly climb to 20.5 and stabilize after about 30 seconds. Based on my field elevation, I should see 27. It does not respond at all to vaccum or pressure. I have tried 3 sensors, two of which are brand new, and even unplugged the sensor completely with the same 20.5 reading. I have verified 5 volts and ground at the appropriate pins on the sensor connector, though the ground is showing 2 ohms through the 180 to airframe ground.

Tonight I will ring out the remaining signal pin to the d-180 connector.

Assuming this pin is correct, I'm out of ideas. What else should I be looking for?
 
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I should have mentioned that this all happens with the sensor port opened to the atmosphere - line disconnected. I also attached a tube to the nipple on the sensor to apply pressure and vacuum.
No change with any method.
 
Do the voltage check quoted below from the D-180 installation manual:
Because of the current drawn by the FlightDEK-D180, even very small resistances between
battery ground and instrument ground can cause voltage differences which adversely affect
engine sensor readings. An easy way to test the quality of the instrument?s ground is to measure
voltage between the ground pin at the FlightDEK-D180 and the ground lead at your aircraft?s
battery. With the FlightDEK-D180 powered on, connect one lead of your voltmeter to a free
ground lead coming from the FlightDEK-D180. Connect the other lead of your voltmeter to the
ground terminal of your battery. The voltage between these two points should measure very
close to 0 mV (within 5 mV). If it does not, you must improve the ground connection between
the ground of your battery and that of your avionics bus.
Click to expand...
 
More troubleshooting tonight and I found the ground pin to aircraft ground bus at 3mv. No smoking gun there, but did find the signal pin one hole off. Moved it over and the thing is acting almost normally. I say almost because it is reading 1.5 inches higher than it should in the "type 1" setting. I'll fly it a bit and see what happens.
 
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