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  #1  
Old 11-21-2020, 03:20 PM
TOGApwr TOGApwr is offline
 
Join Date: Oct 2018
Location: Littleton, CO
Posts: 6
Default G3X manifold pressure stuck at 32"

Helping troubleshoot an EIS hiccup with a friend and his g3x. The MAP is pinned at 32.1" ... and we're in Denver. It should read around 25 or so I believe.

I've tried the configuration page, all options output indications 32 or higher. I've inspected the sensor, braided line to the intake manifold, the mag lines, and wiring. All seems in order.

To be clear it constantly indicates 32 and varies only a few tenths, even when running, and is not a fault X.

This is a new build. Before I recommend a new sensor... any advice on possible setup issues?
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  #2  
Old 11-21-2020, 04:38 PM
Longez's Avatar
Longez Longez is offline
 
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Location: KS
Posts: 139
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Quote:
Originally Posted by TOGApwr View Post
Helping troubleshoot an EIS hiccup with a friend and his g3x. The MAP is pinned at 32.1" ... and we're in Denver. It should read around 25 or so I believe.

I've tried the configuration page, all options output indications 32 or higher. I've inspected the sensor, braided line to the intake manifold, the mag lines, and wiring. All seems in order.

To be clear it constantly indicates 32 and varies only a few tenths, even when running, and is not a fault X.

This is a new build. Before I recommend a new sensor... any advice on possible setup issues?
  1. Make sure the sensor is being powered with +5V, not +12V.
  2. Unscrew the sensor to expose it to ambient and observe the reading to make sure the installation is not holding pressure.
  3. Disconnect the green sensor wire from the GEA 24 and measure the output voltage. This sensor should be outputting <2.5V at your altitude.

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Steve
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  #3  
Old 11-21-2020, 10:23 PM
ethand ethand is offline
 
Join Date: Mar 2013
Location: San Diego
Posts: 195
Default

My RV-10 started to get "stuck" or have an extremely slow MP response and the issue was the small orifice piece that I added to where the sensor screws into the firewall mounted 3 position piece. The hole got plugged over time (.004" hole). Removed the sensor and the orifice piece, cleaned it. No more issues. Added it to the condition checklist.

Not sure how yours was built but could be something to look at

E
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  #4  
Old 11-22-2020, 09:30 AM
lr172 lr172 is offline
 
Join Date: Oct 2013
Location: Schaumburg, IL
Posts: 5,675
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One of two things. Either the sensor failed or has connection/wiring issues. Most sensors go to 32", so some failure modes would show 32". Also, debris has clogged something and locked the higher pressure between the sensor and the blockage. The reduced ambient pressure allows the locked in pressure to increase a bit, giving the somewhat higher than normally seen pressure.

Larry
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  #5  
Old 11-22-2020, 10:02 AM
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Longez Longez is offline
 
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Location: KS
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Quote:
Originally Posted by lr172 View Post
Most sensors go to 32", so some failure modes would show 32". Also, debris has clogged something and locked the higher pressure between the sensor and the blockage. The reduced ambient pressure allows the locked in pressure to increase a bit, giving the somewhat higher than normally seen pressure.

Larry
Agree that it seems likely that the sensor is blocked and holding pressure which is why I recommended he unscrew the sensor to expose it to ambient and rule out this common problem.

The standard Garmin supplied Kavlico manifold pressure sensors will measure to 60 in. Hg., so reading 32 in. Hg. is a LONG way from reaching an overscale condition.

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Steve
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  #6  
Old 11-22-2020, 10:16 AM
lr172 lr172 is offline
 
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Location: Schaumburg, IL
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Quote:
Originally Posted by Longez View Post

The standard Garmin supplied Kavlico manifold pressure sensors will measure to 60 in. Hg., so reading 32 in. Hg. is a LONG way from reaching an overscale condition.

Steve
Sorry, my only experience is with automotive style MAP sensors and the normally aspirated versions all top out at 31 or 32" (they do make 2 bar and 3 bar versions). Dynon (assume AFS also) use GM MAP sensors, as does GRT, so assumed there was a good chance that is what the OP had. Now realize he has a Gamin.

Larry
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Last edited by lr172 : 11-22-2020 at 10:22 AM.
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  #7  
Old 11-23-2020, 08:56 AM
TOGApwr TOGApwr is offline
 
Join Date: Oct 2018
Location: Littleton, CO
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Yeah I think wiring off the top of my head too. I work with them on weekends, so expect more information and any further developments on Saturday.

Thanks for the leads, I'll bring them up!
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  #8  
Old 11-26-2020, 09:56 PM
TOGApwr TOGApwr is offline
 
Join Date: Oct 2018
Location: Littleton, CO
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The guys found the issue. Sure enough, the pins were reversed in the wiring harness that was cut custom for them. Gauge is now operating normally.

Thanks for the tips from everyone, you lead us to check into the pinout first thing
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