Manifold pressure on Garmin gi-275 jumps around.

dcat127

dcat127

Pre-takeoff checklist
Joined
Jun 30, 2020
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The manifold pressure on my gi-275, jumps around, and had been doing this since I bought the plane. I had it at the avionics shop once to look at it, and they made some setting or firmware change to it that made it a bit better. I still think it jumps around too much. They have suggested that they may be able to reroute the tubing or something to improve it further...

Is there a problem or am I just too picky?
View attachment 1000121688.mp4
 
You are not being too picky. That is hot garbage.

Could be a sensitivity issue. Digital sensors are very precise, so the displays normally dampen out minor fluctuations. I assume the 275 has settings in the install menu to adjust that.

Or, it could be another issue. Perhaps a leak in your sensor tubing or somewhere in the air induction system.
 
Is it steady with the engine off? If so, likely not the sensor. If not, it’s the sensor.

Is it steadier at lower MP (idle, off idle, low RPM)? If it gets worse, then likely a leak somewhere - in the gauge tube/fittings or your induction hoses. If it gets better, might have moisture or oil in the low-point of the gauge tubing.
 
It is steady with the engine off. It jumps around a bit at idle, but certainly I would say less than this.

Thanks for the confirmation that it is not normal. It sounds like my mechanic is in the right track to look at the tubing.
 
The engine monitor was installed about 3 years ago, so I would presume it was new at that point. But of course I have no way of proving that.
 
Garmin offers a restrictor fitting (P/N 117-02083-00), which is a .016 restricted orifice to help reduce the jitter that can occur in certain installs. Textron uses a similar restricted orifice (P/N 02G22988) on the G1000 restart aircraft.
 
Oh heck no - yeah, get that fixed.
 
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