D180 hobbs time error

[mhubel]

I have been seeing the hobbs time produce errors. Twice the real engine time was about 2 hours while the hobbs advanced 4 hours. Once on a two hour trip, the hobbs went backward 0.1 hour. During all this, the tach time seemed to be accurate.
The D180 is connected to a Garmin GTN650 through a HS34.
Have there been any similar errors? Any solution?

 

[dynonsupport]

First, as background, the Hobbs timer records the duration of time that engine oil pressure is at 15 PSI or higher.

If this is a new installation, then you should first look at the set up for the oil pressure sensor. If that is wrong, then you could get anomalies.

Have you noticed whether oil pressure is reading correctly? We had a case before where the oil pressure sensor was stuck at a high value, which caused the timer to run more than it should.

As far as the negative value, that doesn't make sense. But check the oil pressure sensor and setup first, and make sure they are okay.

 

[mhubel]

Unfortunately, this is a 7 year old installation and the oil pressure works properly sitting between 60 and 80 PSI (in range for this engine). Even if the oil pressure was stuck reading high at over 15 PSI, the power was not on long enough to explain the 4 hour time advance.

 

[dynonsupport]

We have no ready answer to that; it is strange. Please contact us at support@dynonavionics.com and see if we can help you figure it out.