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Crazy EDM-830?


chrixxer

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Tonight was fun. Picked 3RM up at the avionics shop.
At runup the right mag ran rough and with my shiny new EDM-830 I watched the CHT drop off completely in Cylinder 3. Having been reading through Deakin's APS Seminar on engine management, I know my mag is failing and ... Oh, no, wait, they were IRAN'd ~10 hours ago. Ran through the fouled plug procedure and the next two mag checks were fine. So far so good.
 
Then an hour into the flight, CHT 3 probe started failing intermittently - this had happened to the shop, too, but they'd cleaned the contacts and thought they'd gotten rid of the issue. Okay, NBD, a new probe isn't that expensive, in the scheme of things.
 
But by the time I was another hour into the flight, it was almost comical how many probes I had going bad and coming back online, including both left overs from the EDM-700 and also brand new probes (MAP, OAT). The factory gauges were fine and the engine was running perfectly, so I pressed on.
 
(Later, despite my instructions regarding how I wanted fuel set up (50 gal "main" (to tabs), 14 gal "aux" (full 64 gallons), the shop had set it up with only 50 gallon capacity. Which meant I start getting bogus "LOW FUEL" warnings. Over mountains in the dark. Yay. The totalizer thought I had 9 gallons on board when I landed, but I had 23. (Finally figured out how to set that up on the ground back at TOA.))
 
a6b0f1a7aa127ec5e1fc92769a66d891.jpg
 
Here's the engine monitor going crazy: https://www.dropbox.com/s/q2j5lfauyny5mqk/IMG_6115.MOV?dl=0
 
 
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You can set the tank capacity yourself, see the programming section of the manual.
I would suspect a bad ground is causing you problems.


(1) I know, and I did ("[f]inally figured out how to set that up on the ground back at TOA"). Still annoying not having it set properly by the shop. Even if they'd just set Main to 64, it would have been at least correct.

(2) That seems to be the consensus. Now the question is, how many AMUs to track down and fix? Sigh.



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1 hour ago, chrixxer said:


(2) That seems to be the consensus. Now the question is, how many AMUs to track down and fix? Sigh.

 

 

I agree with the bad ground connection. Could have been a problem with the original 700 installation causing that unit to be intermittent. Two likely areas to look are at the back of display connections or the engine ground connection. I’d start at the engine and follow the JPI wires passing through the firewall. The ground wire is a thin gauge black wire and should be connected to a stud on your vacuum pump. 

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Tonight was fun. Picked 3RM up at the avionics shop.
At runup the right mag ran rough and with my shiny new EDM-830 I watched the CHT drop off completely in Cylinder 3. Having been reading through Deakin's APS Seminar on engine management, I know my mag is failing and ... Oh, no, wait, they were IRAN'd ~10 hours ago. Ran through the foiled plug procedure and the next two mag checks were fine. So far so good.
 
Then an hour into the flight, CHT 3 probe started failing intermittently - this had happened to the shop, too, but they'd cleaned the contacts and thought they'd gotten rid of the issue. Okay, NBD, a new probe isn't that expensive, in the scheme of things.
 
But by the time I was another hour into the flight, it was almost comical how many probes I had going bad and coming back online, including both left overs from the EDM-700 and also brand new probes (MAP, OAT). The factory gauges were fine and the engine was running perfectly, so I pressed on.
 
(Later, despite my instructions regarding how I wanted fuel set up (50 gal "main" (to tabs), 14 gal "aux" (full 64 gallons), the shop had set it up with only 50 gallon capacity. Which meant I start getting bogus "LOW FUEL" warnings. Over mountains in the dark. Yay. The totalizer thought I had 9 gallons on board when I landed, but I had 23. (Finally figured out how to set that up on the ground back at TOA.))
 
a6b0f1a7aa127ec5e1fc92769a66d891.jpg
 
Here's the engine monitor going crazy: https://www.dropbox.com/s/q2j5lfauyny5mqk/IMG_6115.MOV?dl=0
 
 
Sent from my iPhone using Tapatalk



Check the P2 connector on the back of the instrument to make sure it is correctly installed and tight. All of the EGT and CHT probes come in through P2 except if you have a 9 cylinder radial and then P1 carry the extra cylinder leads.

P3 is the MAP and RPM.

P1 is the oil temp an OAT.

P4 is fuel flow and other inputs.

The EGT and CHT probe failures I have seen always involve 1 at a time. Your problem looks like a P2 issue.


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+1 on things that interfere with data transfer... like bad grounds or noise from ignition wires...

Got too many dissimilar errors to be bad probes... MAP was all over the place and EGt/chts looked like a display on some stereo equipment... (graphic equalizer)  :)

Great video, well delivered using DropBox... usually YouTube works and others... not so much.

Best regards,

-a-

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Check the P2 connector on the back of the instrument to make sure it is correctly installed and tight. All of the EGT and CHT probes come in through P2 except if you have a 9 cylinder radial and then P1 carry the extra cylinder leads.

 

P3 is the MAP and RPM.

 

P1 is the oil temp an OAT.

 

P4 is fuel flow and other inputs.

 

The EGT and CHT probe failures I have seen always involve 1 at a time. Your problem looks like a P2 issue.

I thought of that, but the MAP is erratic as well and that means both P2 and P3 would be loose. That would indicate to me the avionics guys are sloppy or careless to have 2 loose connections. How many others?

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Not seen in the videos are hours of flying with rock solid inputs, MAP that tracks the steam gauge perfectly, etc. A ground I could see being that intermittent, but noise from ignition wires (which are all brand new), seems less likely. The shop is normally anal retentive to a fault, doubt I have three loose connectors on the back - though I suppose possible.


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Chrix,

You know this stuff pretty well.

Looks like JPI needs to throw you some customer service. 

Want to send them a link to this thread? Or send them a link to your video...

Their tech people will know what is going on just by looking at it.

No need to fly around with erroneous engine data flashing at you...  :)

Best regards,

-a-

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No expert here - I thought the EGT probes had a tendency to fail but no so much the CHTs.  

I would tighten the connection of probe to the harness first.  A coating of this stuff at those contacts before tightening has worked wonders for me, when multiple A&Ps and a seasoned avionics guy, could not figure it out:

https://www.ebay.com/i/401220614697?chn=ps

JPI customer service is probably the  - they have yet to lead me in the right direction on any particular issue.  

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No expert here - I thought the EGT probes had a tendency to fail but no so much the CHTs.  
I would tighten the connection of probe to the harness first.

He has problems with MAP, OAT, Oil ....plus multiple CHT and EGT probes, it’s not just 1 probe.
Probably just a loose ground, easy to fix, hard to find.
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I thought of that, but the MAP is erratic as well and that means both P2 and P3 would be loose. That would indicate to me the avionics guys are sloppy or careless to have 2 loose connections. How many others?


I don’t recall the wiring harness setup that JPI provides but if they ship the connectors for the installer to install after cutting the harness to the correct length, they could have made up the connectors incorrectly. Not sure I have ever heard of that many individual sensor failures due to probes or the JPI box itself.


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I don’t recall the wiring harness setup that JPI provides but if they ship the connectors for the installer to install after cutting the harness to the correct length, they could have made up the connectors incorrectly. Not sure I have ever heard of that many individual sensor failures due to probes or the JPI box itself.


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If the connections were setup incorrectly, how would they read correctly 99% of the time?



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If the connections were setup incorrectly, how would they read correctly 99% of the time?



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If the connectors were crimped incorrectly, engine vibration could cause intermittent contact. I would check all of the connectors on the back of the JPI to make sure they are snug (screwed in) and give a gentle tug on a few of the wires to see if there is any play in them.

What your video is showing is a connection issue. That error message you cleared can be a bad probe or it can be a loose connection. Like this RPM issue.



Or this loose connection on EGT 4

78954ee40d135daefe611cd57e1c8eac.jpg

The fact you are seeing this on a number of different sensors I would look for a connection issue before I shipped the unit to JPI. I’ve seen enough of these JPI issues to write a book.

Oh yeah, another chapter. Fuel mismatch error message.

28b1d5e01475d70a785339784fce5130.jpg




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