Restraining and mounting and protecting wiring harnesses forward of the firewall?

[claycookiemonster]

My Dynon and VPX set up included several significant wiring harness connectors to gather the EGT and Head Temp etc sensor readings. Given the length of the connectors on the engine, it seems those multi-pin connectors will go forward of the firewall. Or am I wrong? I'm not inclined to add an extra length of wire to move the connector behind the firewall, as that adds another splice.

What is the best way to manage and secure and protect these connections? And where best to locate them?

 

[John Tierney]

My EMS module is in the cockpit on the subpanel. All of the EGT/CHT etc. wires are plenty long to reach the cylinders on my RV-7A. As far as wire restraints, I have lots of adel camps, many stacked together from engine mount to wire bundle.
For sensor wire I have a small terminal block on the forward side of the firewall, since they are usually 5V devices.

 

[riseric]

Clay, which multipin connectors ?
Those that connect to sensors, i.e. fuel and oil pressure sensors and manifold pressure sensor are connected to their respective sensors FW/FWD. They were butt-spliced and extended through the firewall.

As for the EGT/CHT probe wires, I didn't want to splice them as I feared/understood that they were of a special kind. So I bought the appropriate spade connectors and extended the wiring, leaving the spades FW/FWD. I bunched them up near the lower firewall and protected the lot with silicone tape before securing to the engine mount. I can get photos if needed.

 

[wirejock]

EMS

I battled that one too.
As John mentioned, CHT/EGT was fine. I did trim so the loop was uniform.
The 37-Pin EGT cable was another story.
I tried Faston but the bundle was the size of a baseball and I felt it woule fail.
I tried a terminal strip but it weighed almost a pound. Nope.
The final solution was a 37-Pin D-Sub. I terminated all 37 pins on a Female and secured it FWF. The sensors all terminate on the Male. If I need to add a sensor, just add it to the Male. Much cleaner.

 

[bjdecker]

... I terminated all 37 pins on a Female and secured it FWF. The sensors all terminate on the Male. If I need to add a sensor, just add it to the Male. Much cleaner.

Larry,

What comprises the wiring from the 37pin connecter back to the EMS module??

 

[RV7A Flyer]

I battled that one too.
As John mentioned, CHT/EGT was fine. I did trim so the loop was uniform.

As others have noted, yes, this was fine and I did the same to trim them up a bit. The EGT/CHT harness is on a DB25, and the wires are 6' long, so plenty to go around.

But I ditched the spade connectors after the umpteenth wonky signal from an EGT or CHT sensor, and went with Omega mini-connectors. Rock solid ever since.

The 37-Pin EGT cable was another story.

I think you mean the 37-pin *Engine Sensor Main Wire Harness*, not the EGT/CHT harness. This one is also 6' long, which was plenty long enough for everything that I can recall (it's been over 10 years, so memory fades). If there *were* any that required a wire more than 6', I probably just bought some of the correct color code from Stein or somewhere else. No butt splices or terminals, other than one to distribute both 5V and 12V to things like capacitive converters and the like.

I tried Faston but the bundle was the size of a baseball and I felt it woule fail.
I tried a terminal strip but it weighed almost a pound. Nope.
The final solution was a 37-Pin D-Sub. I terminated all 37 pins on a Female and secured it FWF. The sensors all terminate on the Male. If I need to add a sensor, just add it to the Male. Much cleaner.

I did add one or two things, like an Aithre remote CO detector, and just added wires directly to the DB37 that plugs into the EMS. A bit of a pain to do it under the panel, but how many times do you have to add sensors after you're flying?

BTW, how do you just add a sensor wire to one half of the connection? You'd still have to run a wire from the female back to the EMS, unless you wired *every* pin on both ends when you installed it?

 

[wirejock]

EMS

Larry,

What comprises the wiring from the 37pin connecter back to the EMS module??

My EMS was supplied with two cables. The CHT/EGT cable and a 37-Pin Sensor cable. I have a spreadsheet if you want.
Since virtually all of the sensors are FWF, I just added a female to the end of the cable. Pin for pin. Tested every circuit. It's secured FWF.

<snip>

I think you mean the 37-pin *Engine Sensor Main Wire Harness*, not the EGT/CHT harness. This one is also 6' long, which was plenty long enough for everything that I can recall (it's been over 10 years, so memory fades). If there *were* any that required a wire more than 6', I probably just bought some of the correct color code from Stein or somewhere else. No butt splices or terminals, other than one to distribute both 5V and 12V to things like capacitive converters and the like.

Yes. 37-Pin EMS. I need to slow down. Yes, 6' is enough to get forward. It depends on where the EMS-220 is mounted. Some sensors needed additional wire to connect. I just felt it easier to terminate the entire 37-pin harness FWF with a female. All the sensors are terminated into the Male. The female/male connectors are secured where I can easily separate, troubleshoot, add sensors without any under panel work. Some wires were short. A few were a bit longer. My EMS module is on a drop down hinged panel so I can work on it no problem.

BTW, how do you just add a sensor wire to one half of the connection? You'd still have to run a wire from the female back to the EMS, unless you wired *every* pin on both ends when you installed it?

My EMS came with a 37-pin harness. I just terminated it on a Female FWF. So every wire is on the Female connector in the FWF area. Unconventional.

If I were to do it over, I would either ask Dynon for a 10' or 12' EMS harness and run each wire to it's destination or do as you describe and run new wires the correct color. Excess would be clipped or secured for future use. I found out later they would make almost any harness any length. Much cleaner but mine is done and I do have access to all the extra pins.