Digital oil pressure

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ruddersup?
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Digital oil pressure

Post by ruddersup? »

I'm an analog not digital guy but got talked into a glass panel in my amateur built amphib. Is it common to have the digital oil pressure gauge fluctuating up to 8 psi? Everything else normal.
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ahramin
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Re: Digital oil pressure

Post by ahramin »

Absolutely not.

Constant speed prop or fixed pitch?

The biggest advantage to the digital engine monitors is that they record everything. These recordings make tracking down problems like these in a scientific manner much easier. Read your manual or get help and download the data. Post it here or pm me and we'll figure out where the problem is.
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digits_
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Re: Digital oil pressure

Post by digits_ »

ruddersup? wrote: Sun Sep 15, 2024 8:26 am I'm an analog not digital guy but got talked into a glass panel in my amateur built amphib. Is it common to have the digital oil pressure gauge fluctuating up to 8 psi? Everything else normal.
During cruise it's not. They usually have some kind of software to filter high frequency variations. Sounds like a broken sensor or more likely some interference from high frequency or high power signals, likely mags or alternator.

Depending on the inner workings of your system, the interference is not necessarily happening on your oil pressure sensor wire, although it is most likely.
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

Constant speed prop. Have very slight movement (noticeable) in mp and rpm.
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digits_
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Re: Digital oil pressure

Post by digits_ »

ruddersup? wrote: Mon Sep 16, 2024 12:32 pm Constant speed prop. Have very slight movement (noticeable) in mp and rpm.
Are those digitally measured and displayed as well? Can you hear the rpm changes as well, or could it be 'just' a sensor issue?
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

Yes, dammm it, lol.
I do hate this system, but the future.
However last week we (more trouble shooting on another prob), checked play in throttle cable and there was about 1/4" play Then noticed carburetor full throttle went past carb stop and we took carb apart to see if more than full throttle had any effect on fuel flow and determined no. I thought I was losing full power but it turns out it's me.
However the pulsing oil pressure gauge still remained (maybe less) and I must say the mp and rpm movement is less (barely visible).
Yes we are very familiar with the inside of engines.
Hoping someone might have experienced this but so far not.
Always thanks for input.
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Re: Digital oil pressure

Post by digits_ »

ruddersup? wrote: Mon Sep 16, 2024 12:45 pm Yes, dammm it, lol.
I do hate this system, but the future.
However last week we (more trouble shooting on another prob), checked play in throttle cable and there was about 1/4" play Then noticed carburetor full throttle went past carb stop and we took carb apart to see if more than full throttle had any effect on fuel flow and determined no. I thought I was losing full power but it turns out it's me.
However the pulsing oil pressure gauge still remained (maybe less) and I must say the mp and rpm movement is less (barely visible).
Yes we are very familiar with the inside of engines.
Hoping someone might have experienced this but so far not.
Always thanks for input.
The biggest downside with the digital systems is that you can't always trust them. The majority of issues indicated on glass cockpits have turned out to be sensor or wiring issues, both on fancy high quality ones, and the cheap(er) alternatives.

Is it possible to temporarily hook up an analog gauge to verify the oil pressure readings are actually correct?
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

digits,
Well that is a good idea. Maybe just throw out the digital. I've never seen a wet gauge fluctuate.
Thanks will do as suggested
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

However a wet line has lots of dampening so might not show the problem.
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digits_
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Re: Digital oil pressure

Post by digits_ »

What's the brand/model of engine monitor you're using?
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

Dynon EMS-D120
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ahramin
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Re: Digital oil pressure

Post by ahramin »

ruddersup? wrote: Mon Sep 16, 2024 12:32 pm Constant speed prop. Have very slight movement (noticeable) in mp and rpm.
That confirms your oil pressure is fluctuating and it's not a sensor issue. I would ground the aircraft immediately. Do you have an oil filter? I would do an oil change and check the screen and cut open the oil filter. Take the prop governor off and inspect the screen up there as well.
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

Well we recently put new lifters in and changed oil, but we are now going at the pressure relief valve and governor and ..... Decided a wet line might not tell us anything right now until we trouble shoot some more.
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RayJr
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Re: Digital oil pressure

Post by RayJr »

I had a similar problem and managed to fix it.

I installed a full glass panel from scratch in my Vans RV last year. The SINGLE issue I had with it after turning it all on for the first time was a wildly fluctuating fuel pressure.

The connection from the fuel pressure sensor to the EFIS wasn't perfect. It connected fine but left a little bit of exposed wire between the wire sleeve and the connector. Enough that it was letting interference into the signal. To test the fix I wrapped the connection in electrical tape and it worked like a charm. It is still working good with just the tape. I will redo the connection next time I have the cowl off.

Good luck
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Re: Digital oil pressure

Post by digits_ »

To clarify: I wasn't suggesting to put a whole wet line on there. On my plane it was relatively easy to add an oil pressure gauge right at the engine, by putting in a T junction at the oil pressure line. Not sure if that would work in your case, but that should also eliminate the wet line dampening.
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

Thanks for that info.
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

digits - can do no problem
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ruddersup?
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Re: Digital oil pressure

Post by ruddersup? »

We put a restrictor in the line and the pulsing is gone, whew.
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