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Dynon MAP sensor failure

Italiancowboy

Active Member
I have the Dynon HDX system and flying home yesterday got the big red "X" on the Manifold Pressure display (system is about 5 years old and 300 hrs).

I assume it the MAP sensor as everything else worked normal (MAP must just go to monitoring and not used in any engine performance software).

MAP sensor is mounted on the engine side of the firewall which Dynon says is ok but Van's installation on MAP sensors says to put it in the cabin side of the firewall (less harsh environment).

Questions:
Anybody out there have a Dynon MAP sensor failure ?
What are the causes ?
What are the ramifications ?
 
Check wiring first

Check your connections are still good first. The sensor is normally very reliable but in the event of failure they are easily available. Aircraft Spruce will have them listed under the Dynon part number but it is actually a GM automotive sensor. The only other data you lose with a failure is the Percent Power indication.
 
MAP sensor is mounted on the engine side of the firewall which Dynon says is ok but Van's installation on MAP sensors says to put it in the cabin side of the firewall (less harsh environment).

Dynon uses the 90's/00 era GM MAP sensor. It is designed for under hood placement and can handle the heat. It was typically bolted directly to the intake manifold, so exposed to significant heat and would last for decades. Cheap off shore variants likely don't last as long.
 
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Same issue for Fixed pitch prop and firewall forward position

I’m chasing the same issue but have not yet resolved it. The sensor sometimes works fine at startup, but then slowly fails over a few minutes. Occasionally it will recover momentarily. I have replaced the sensor three times. They will work for a while, but eventually fail. The last sensor lasted less than a month. The wiring appears fine. I have an off brand sensor that Dynon offered as an alternative that I will be installing shortly to test and will take a closer look at the wiring and the hose.

https://www.bmotorsports.com/shop/p...cts_id/1582?osCsid=0g4q5pmrgahce1skfb7aua29b7

The failure mode is curious. It will be working fine, but then without changing power settings will slowly drift down until the red X is displayed. Then sometimes later in the flight will come back on line for a while. If there were a pressure line blockage of some sort, it doesn’t seem likely that the pressure in the line would decrease towards full vacuum. But I will check for any contaminants.

If there were a short in the 5V power or signal wire, the indications should be erratic or sharply on or off rather than a gradual reduction towards zero. The odds of getting three bad sensors seems pretty low.
 
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