JPI900 Oil Pressure

[ValkyrieRider]

I FINALLY got my M20C back yesterday after installing some new Avionics, adding an Alternator, and completing an annual.  

Part of the new Avionics was the addition of a JPI 900.  Because of the heat in Phoenix, mid day yesterday, we decided to not test the engine yet.  But, we taxied around the airport, performed a couple run-ups, and then did a high speed taxi on the runway.  So far, from these ground checks, everything seems to be working great, with one exception - the oil pressure.  The JPI showed the oil pressure in the upper yellow value during most low RPM operations on the ground, and even at high (take off) RPM it barely moved over the line to green, and really hovered on the line between the two.  We plan on taking it up early Saturday morning to test fly it - then I had a short trip after, but there is concern about the oil pressure reading.  During pre-flight, the oil level was about 6 1/2 QTs.

The avionics installer has said that there is nothing wrong as long as it is in the yellow/line/green area.  He also said that there is pilot adjustable calibration that should be done, but I haven't found anything about that yet (could be that I am blind).  Any help?  Thoughts?  

 

Edited June 14, 2019 by ValkyrieRider
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[ArtVandelay]

What did the oil pressure read before you started the engine?

I would sanity check all probes readings.

 

Tom

 

[ValkyrieRider]

5 minutes ago, ArtVandelay said:

What did the oil pressure read before you started the engine?

I would sanity check all probes readings.

 

Tom

 

I have a pre-oiler, so part of my start-up includes turning on the pre-oiler, which usually adds oil pressure to the engine.  Once that is stabilized (usually about 15 seconds or so) I turn off the pre-oiler and then finish with the start-up.  Prior to pre-oil, "I believe" it read zero as the JPI was starting up, but I didn't really catch it.  

[kortopates]

First, I am sure the oil pressure is reading correctly given its installed where the OEM sensor was previously installed.

It's more likely you may just be discovering now that your oil pressure may be near the lower limit for cruise - which is probably 60 psi (but check your POH limitations section).

There isn't a calibration for the sensor but the engines oil pressure regulator is adjustable by your A&P.

 

Another thing that may be effecting this is oil temp. As temp goes up oil pressure declines. So if it got hot taxing around and doing run-ups, that is going to bring down your pressure as well.

 

But remember green arc is for cruise, yellow is only for low RPM idle.

Lastly, since the 900 is wired to the main buss, it'll be on before you start the engine and you can see your cold oil pressure at startup which should be higher.

 

 

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[ValkyrieRider]

10 minutes ago, kortopates said:

First, I am sure the oil pressure is reading correctly given its installed where the OEM sensor was previously installed.

It's more likely you may just be discovering now that your oil pressure may be near the lower limit for cruise - which is probably 60 psi (but check your POH limitations section).

There isn't a calibration for the sensor but the engines oil pressure regulator is adjustable by your A&P.

 

Another thing that may be effecting this is oil temp. As temp goes up oil pressure declines. So if it got hot taxing around and doing run-ups, that is going to bring down your pressure as well.

 

But remember green arc is for cruise, yellow is only for low RPM idle.

Lastly, since the 900 is wired to the main buss, it'll be on before you start the engine and you can see your cold oil pressure at startup which should be higher.

 

 

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First of all, thank you for your response and information, it is valuable.  I hadn't considered that yellow arc would be acceptable for low RPM.  Based on your response, it seems you wouldn't be concerned with the reading, and I should monitor it during cruise to verify if it moves into the green.  After that test flight, I may want to discuss with the A&P about adjusting the oil pressure regulator?

I will also be sure to check the JPI prior to turning on the pre-oiler to see where the cold reading is (or as cold as Phoenix summer gets).  

[kortopates]

First of all, thank you for your response and information, it is valuable.  I hadn't considered that yellow arc would be acceptable for low RPM.  Based on your response, it seems you wouldn't be concerned with the reading, and I should monitor it during cruise to verify if it moves into the green.  After that test flight, I may want to discuss with the A&P about adjusting the oil pressure regulator?
I will also be sure to check the JPI prior to turning on the pre-oiler to see where the cold reading is (or as cold as Phoenix summer gets).  

Exactly, but you don't have to not use the pre-oiler. I don't know where it's plumbed in but would guess a galley port on the side or past the oil pump. Thus it won't effect your start up oil pressure, just move some oil through the engine. You won't see more than 0 till the engine is turning over with the starter or right after it starts up. Look for how high it comes up too before it comes down. With the Phoenix heat it won't be as dramatic as a cold morning start with thick oil that thins at operating temp.
You'll probably have to download the data to really see the details after the event. Set up a free account on Savvyanalysis if you haven't yet and then fly our Savvy Test profile and start learning how to use your new monitor!


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[EricJ]

Your oil temps are pretty high in the pics, so, as has been mentioned, as the temps come down the pressure may go back up.

 

[KSMooniac]

Your CHTs are very high too, which increases oil temp and decreases oil pressure...they're all related. Oil pressure is easily adjusted higher by an A&P by turning a screw, or removing the regulator and adding washers as needed and reinstalling.

More pressure is always better in a Lycoming, so I'd encourage you to get it cranked up into the upper limit of the green.

You should also carefully examine your baffles or doghouse and seals, close up gaps, etc to get those CHTs down below 400 and hopefully 380. That will help decrease the oil temps too.

Lastly you might verify proper vernatherm performance and check the oil cooler for obstruction, bent fins, etc.

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[Tommy]

Echo the sentiment. The lowish normal oil pressure in isolation isn't a problem and can be easily fixed.

It's the combination of high oil temp, high CHTs, and low oil pressure that is of greater concern. First we need to know if these are consistent with your previous readings on OEM gauges to see if it's a calibration problem. If it's consistent, then your engine definitely needs a bit of look at +/- tweaking. You never know, they might be all related (if you are lucky). And yes, high oil pressure is good for Lycoming. 

Edited June 14, 2019 by Tommy

[bonal]

Some points to consider keep in mind this is a C and he is doing high rpm ground runs with an OAT at 103 degrees I bet there aren't too many dog house Mooneys that can keep it under 400 degrees in these conditions. I agree the temps and oil pressure do have a relationship and as such your pressure is low compared to what I am used to seeing in my C. When things are running hot and hot I still see at least 75psi in cruise and around 80 in climb with CHT around 360 and 400 respectively on my factory gauge.

[Jim Peace]

On 6/14/2019 at 4:35 PM, ValkyrieRider said:

I FINALLY got my M20C back yesterday after installing some new Avionics, adding an Alternator, and completing an annual.  

 

You will love the JPI 900.  Be sure to change your fuel gauges to read gallons instead of the display you have.  

I think your oil pressure will be fine once you can check it on a cooler day in flight.  Take a picture of it in cruise for us.

good job in getting the optional CRB temp.

did you consider adding the optional FF?

Beware you will get a high fuel pressure indication at times.  Its a known issue with the JPI900 and Mooney and their numbers in the POH and JPI not wanting to deviate from the high pressure limits.  Some owners have changed out some fuel tubing they found suspect and it changed it a bit....

[MIm20c]

I agree with Jim about the FF sensor which should have been included with the kit. It might be a programming oversight as to why it’s not displaying. Please keep an eye on the max RPM as you fly the plane in the near future. You might need to lower the governor setting slightly.  

[ArtVandelay]

I didn’t think FF was optional on the 900, it’s certified equipment, I thought everything was standardized. Maybe carburetor engines are different? If you didn’t connect it to the GPS then you won’t get fuel to next waypoint, fuel mileage readouts.

Wow, those cylinder temperatures are high, I have my prealarm set to 395°, and will only occasionally reach that on climb out. Maybe you should consider flying in the early morning hours, that’s what I do.


Tom

[carusoam]

M20C cylinder cooling is always a challenge...

the square dog house, and guppy mouth weren’t designed for the best airflow that is needed.

Make sure all the sheet metal is correct.  Holes filled. Seals working around the starter and alternator... that kind of thing..

+1 on controlling rpm... overspeed is a measurable challenge... how much for how long...

Best to stay on target...

Best regards,

-a-

[Brian E.]

I just recently installed a EDM 900 as well and have a couple of thoughts:

- Fuel flow was not an option, it came with the standard installation package.  However, there is an option on the setup to turn the FF data display on/off.  Check the pilots manual for how to adjust.

- The higher data resolution provided by the new digital devices far exceeds whatever analog  manufacturer gauges you had.  My previous gauges we always in the "green".  Now, I too have low oil pressure at idle and cruise as well.  I will have the oil pressure regulator adjusted to bring me in the middle during cruise ops.

 

Best,

brian

 

[ValkyrieRider]

On 6/15/2019 at 8:33 PM, Jim Peace said:

You will love the JPI 900.  Be sure to change your fuel gauges to read gallons instead of the display you have.  

I think your oil pressure will be fine once you can check it on a cooler day in flight.  Take a picture of it in cruise for us.

good job in getting the optional CRB temp.

did you consider adding the optional FF?

Beware you will get a high fuel pressure indication at times.  Its a known issue with the JPI900 and Mooney and their numbers in the POH and JPI not wanting to deviate from the high pressure limits.  Some owners have changed out some fuel tubing they found suspect and it changed it a bit....

Jim, 

I wish I read your post before taking the plane on a maintenance run.  Throughout the orbiting over the airport, the fuel pressure was high, then entire time.  I was trying to figure out why it wasn't high previously, on the ground, and regardless of the electrical fuel pump, the pressure remained high.  The mechanic and I took it out today, and after about 10 minutes, the fuel pressure sat perfect in the middle of the green.  I didn't do anything different ... now with your comment, it makes sense.

[ValkyrieRider]

On 6/15/2019 at 8:45 PM, MIm20c said:

I agree with Jim about the FF sensor which should have been included with the kit. It might be a programming oversight as to why it’s not displaying. Please keep an eye on the max RPM as you fly the plane in the near future. You might need to lower the governor setting slightly.  

Prior to the JPI900, I don't believe I ever went over 2700 RPM, so I was surprised when it went there during practice runs.  I will have to watch that on take off in the future.

[ValkyrieRider]

16 hours ago, Brian E. said:

I just recently installed a EDM 900 as well and have a couple of thoughts:

- Fuel flow was not an option, it came with the standard installation package.  However, there is an option on the setup to turn the FF data display on/off.  Check the pilots manual for how to adjust.

- The higher data resolution provided by the new digital devices far exceeds whatever analog  manufacturer gauges you had.  My previous gauges we always in the "green".  Now, I too have low oil pressure at idle and cruise as well.  I will have the oil pressure regulator adjusted to bring me in the middle during cruise ops.

 

Best,

brian

 

I will check the setup when I go back to the airport, thank you.

[Jim Peace]

On 6/15/2019 at 11:45 PM, MIm20c said:

I agree with Jim about the FF sensor which should have been included with the kit. 

It is an option

[jonhop]

 

[FloridaMan]

You may be annoyed about where you installed it because of that required "ENGINE" light. When you pull power to idle to land, it'll blink yellow. If your prop holds 2700RPM, it'll blink red. 

Is it coupled to your GPS? I wrote a piece of software that converts my JPI downloads to logbook entries. Includes start/destination airport and day/night flying.