Relabel sensors EDM-700?

[AndreiC]

I discovered recently that what my EDM700 thinks are EGT sensors 1-4 are completely messed up: 1 is actually 4, 2 is 1, and 4 is 2. The CHTs are correct. I want to make this right. 

While switching around sensors on the same side of the engine is easy, once cylinder 4 gets involved it is more complicated — wires need to be rerouted.

My question is if anyone knows if the EDM700 can do the renumbering in software: is there a way to program it to tell it that what it now thinks is cylinder 1 should be 4, etc?

[MikeOH]

Why can’t you rewire at the instrument/connector?

[FlyingDude]

The wires are labeled all throughout. Just rewire them in the engine compartment. Their end terminals connect to the thermocouple ring terminals by screws. 

Plus, if you do a swap in sw to fix a swap in hardware, c'mon that's clumsy. Not unlike anybody doesn't object to not avoiding double negatives.

[FlyingDude]

18 minutes ago, MikeOH said:

Why can’t you rewire at the instrument/connector?

The labels on the wires would still not match the pin out...

[MikeOH]

1 hour ago, FlyingDude said:

The wires are labeled all throughout. Just rewire them in the engine compartment. Their end terminals connect to the thermocouple ring terminals by screws. 

Plus, if you do a swap in sw to fix a swap in hardware, c'mon that's clumsy. Not unlike anybody doesn't object to not avoiding double negatives.

Well, I think the OP stated that wouldn't be so easy since the miswiring crosses over the engine...and he stated he was trying to avoid rerouting.

And, while kludgey, having the labels wrong at the connector seems an easier fix than a software kludge

[FlyingDude]

24 minutes ago, MikeOH said:

Well, I think the OP stated that wouldn't be so easy since the miswiring crosses over the engine...and he stated he was trying to avoid rerouting.

And, while kludgey, having the labels wrong at the connector seems an easier fix than a software kludge

Technically you are right but you cannot sacrifice airworthiness for comfort...  Stuff needs to match.  Think about the next owner and his mechanic.  Or even the A&P who is allegedly supervising OP's work (as I assume the OP is not one and this is not preventative maintenance)...  

JPI connectors come pre-built and the wires have labels printed on them at every 6 or 12 inches.  If the wires were labeled only at the tips or if those labels could be modified, then yea, go ahead and swap the labels also while swapping the bits in the configuration.  That would be an easy fix without going through the PITA rerouting...  But having an instrument pinout that does not match connector pinout or the wiring labels or the connected instruments...  C'mon man, it's just hairthin thermocouple wire.  Just reroute it.  We're not talking about girthy oil cooler hoses...

 

[Pinecone]

Uuuh, maybe move the wires at the connector and RELABEL THEM.

[FlyingDude]

1 minute ago, Pinecone said:

Uuuh, maybe move the wires at the connector and RELABEL THEM.

Anything but do it right.

[AndreiC]

My concern was that if there *was* an option for the indicator to have already been relabeled in software by a previous owner, I would have liked to undo that. 
 

[Shadrach]

4 hours ago, MikeOH said:

Why can’t you rewire at the instrument/connector?

While I have no doubt that YOU could move the pins on the connector, it is intimidating for someone that's never done it. Also, if his JPI is as much of a PITA to get to as mine, I would be seeking any other alternative.  It would be nice if the allowed you to program the read out to the connector of your choice.

[Shadrach]

5 hours ago, AndreiC said:

I discovered recently that what my EDM700 thinks are EGT sensors 1-4 are completely messed up: 1 is actually 4, 2 is 1, and 4 is 2. The CHTs are correct. I want to make this right. 

While switching around sensors on the same side of the engine is easy, once cylinder 4 gets involved it is more complicated — wires need to be rerouted.

My question is if anyone knows if the EDM700 can do the renumbering in software: is there a way to program it to tell it that what it now thinks is cylinder 1 should be 4, etc?

I just redressed and re routed my JPI harness while adding a transducer line, it really isn't that big of a deal to reroute...maybe a few hours. 

[FlyingDude]

https://www.aircraftspruce.com/catalog/pdf/edm830manual.pdf

It contains all the answers 

[kortopates]

Three of the 4 EGT wires are being moved, just let the mechanic undo the mess forward of the firewall and re-route them properly.
After a job like that i’d half expect to see them bundled with ignition needs too which would need to be corrected as well.

But consider if going to this trouble, it could be a good time to upgrade the display head to a modern color 830 through their upgrade program where you return your 730 display. It was costing about $1200 after exchange. It’s a good deal if you have the panel room since it’s bigger.


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[laytonl]

Relabeling the wires is not difficult.  I just print out labels in 6 pt type and the put them on the wires with clear shrink wrap.  It’s a lot easier to read than JPI’s fine print.

[Aerodon]

On 7/9/2024 at 10:46 AM, AndreiC said:

My concern was that if there *was* an option for the indicator to have already been relabeled in software by a previous owner, I would have liked to undo that. 
 

Not possible to re-assign by software.  If you need some JPI thermocouple wire to extend any of the wires, send me a note, I have offcuts.  Also replacement ring terminals and screws and nuts.

 

Aerodon

 

 

[AndreiC]

On 7/9/2024 at 3:37 PM, kortopates said:

After a job like that i’d half expect to see them bundled with ignition needs too which would need to be corrected as well.

@kortopates: I looked at them yesterday, and on the last stretch (underneath the cylinders) they are indeed zip-tied to the ignition leads. What is wrong with that?

The wires are also not labeled -- no idea if this is an earlier installation, from before JPI started shipping pre-made harnesses or what, but they are just some yellow, relatively thin cables with two electrical wires inside.

[Fly Boomer]

2 hours ago, AndreiC said:

The wires are also not labeled -- no idea if this is an earlier installation, from before JPI started shipping pre-made harnesses or what, but they are just some yellow, relatively thin cables with two electrical wires inside.

Not "just some yellow, relatively thin cables with two electrical wires inside."

From the JPI website:

"JPI uses K-type thermocouple wire...color code of Red and Yellow in a Yellow jacket:
‘Red’ (-) (Nickel-Aluminum or just “Alumel”)
‘Yellow’ (+) (Nickel-Chromium or just “Chromel”)"

[kortopates]

[mention=7862]kortopates[/mention]: I looked at them yesterday, and on the last stretch (underneath the cylinders) they are indeed zip-tied to the ignition leads. What is wrong with that?

It’s a very amateurish installation to do that. See the JPI installation instructions prohibiting this.
Why? The thermocouples produce a very low current with only few millivolts. That makes the wires very sensitive to interference from high voltage ignition wires and high current wires like alternator output cables.
The thermocouple wire harness needs to be routed independently without being bundled with other electrical wires else the result is very noisy EGTs and CHTs.
Very frustrating to say the least after spending a lot of $ on labor and an engine monitor and get noisy signals because the installer couldn’t follow directions.


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