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EMI Shielding question


Alex3000
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Calling all electrical nerds.

For my megasquirt install I am using a Hall sensor and trigger wheel.

 

I bought a roll of 1/4" EMI shielding for the wires but it ended up being an insane PITA even to get it over one 5 foot wire let alone all 3. So I shielded and grounded (to the ecu) JUST THE SIGNAL WIRE, and not the power and ground wire.

 

Could this be an issue? could interference come into the power wire and translate through the signal return or something like that? It is 12V so maybe not a huge deal?

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1 hour ago, SonsOfIrony said:

If you're worried.  Just wrap the power and ground in a second shield ground, and terminate it near the ECU.

 

So, I can't find EMI shielding that is wrap, only the continuous sheathing.  I can get why that is but the sensor is all wired into the harness.

It's possible I'm overthinking this.  Plan is to start the car next weekend so just wanted to make sure there are no x-factors.

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AFAIK, the signal wire is the only one you need to be worried about, so you’re good now. 

Also, you would want to shield them individually... putting multiple wires in the same shield would defeat the purpose!

Edited by enginerd
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30 minutes ago, enginerd said:

AFAIK, the signal wire is the only one you need to be worried about, so you’re good now. 

Also, you would want to shield them individually... putting multiple wires in the same shield would defeat the purpose!

 

Correct.

 

Shielding is also really only a big issue if your CAS/CPS run in line with high voltage or high RF issues like charging circuits, or coil drivers/ignitor lines.  If they just cross, it should be fine.

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1 hour ago, Team Infiniti said:

What about creating a twisted pair (signal+ shield ground)with a powerdrill?

 

OEM runs twisted ABS wires ( AC generator....non Hall)

You can purchase shielded wire in a 2 or 4 conductor arrangement from Amazon:  https://www.amazon.com/gp/product/B071P7CBZ2   You can even select between black and OEM gray, or as they say on the spool 'choose all your desire.'

 

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2 hours ago, enginerd said:

AFAIK, the signal wire is the only one you need to be worried about, so you’re good now. 

Also, you would want to shield them individually... putting multiple wires in the same shield would defeat the purpose!

 

Interesting, I thought I was trying to avoid interference from the general engine bay. Say, if the wire ran close to the alternator or ignition coils.

For what it's worth, I initially fully twisted the whole bundle (and got a massive blister) and then tried to thread the whole twisted set through the shielding, which didn't work.

I then shielded just the signal wire and tried to twist the set and the twisting started mangling the wire shielding so I figured I would just let it alone.

 

All my wiring for the various sensors and coils etc are all run separately in there own plastic split loom.

 

***Followup question that just occurred to me!!!

 

I am running 4 individual LS coils that are fed a 5v square signal.  Is it an issue that the coil power and ground wire for each coil are running in the same bundle as the signal and signal ground???

 

I only shielded the hall sensor since the megamanual told me to... I really didn't consider other potentially vulnerable circuits. 

 

 

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46 minutes ago, bbaker480 said:

You can purchase shielded wire in a 2 or 4 conductor arrangement from Amazon:  https://www.amazon.com/gp/product/B071P7CBZ2   You can even select between black and OEM gray, or as they say on the spool 'choose all your desire.'

 

 

Thanks for this.  There is A LOT I would do differently the second time around.  But I think that's true of life in general.

 

Also, in my head, the wiring portion of this project was to be a negligible expense... 10 trips to pepboys later I spent about $400 bucks this weekend between 35' of battery cable (Sure, move the battery to the back, oh yeah weight distribution, oh yeah) and then drawing everything out on paper (wait i need HOW MANY relays!).  You want HOW MUCH for those shitty Chinese fake copper terminals?!!!

 

Also, I budgeted like one day for wiring. Run some wires, what's the big deal? Let's just say I have adjusted my timetables.

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When @Crank Yankers Racing made the trip out to us to rewire his car I figured on a day and a half.  We started on Thursday and the car left about 70% completed Sunday.  Tyler came prepared with a huge box of goodies like a new fuse and relay box, more weatherpak connectors than you'd need to build 2 cars, and seemingly miles of wire.  We STILL ended up at our local place picking up parts that like your battery cable were shockingly expensive.  

 

V2.0 on my car I might break down and buy the $80 wiring harness for the MS2 just to make tracing the harness wires easier.  I love that I can look at any of our cars right now and know that purple =  fuel pumps, orange  = IGN+, and so on but the individual engine harness would be a lot easier to work on if I just start new and wire in connectors where they need to be instead of splicing wires.  

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Oh yeah wires are so much fun…

 

wires1.thumb.jpg.43098591936dc4b4df086204b6d316d6.jpg

 

Especially if you are all anal and want to be able to easily work on the car later. I bought a heat shrink tube printer so I could label the various connectors which really helped.

 

wires2.thumb.jpg.0389fabbd46c605b74cc740a7f010322.jpg

 

 

Here is another big tip for you guys, don’t waste time working with GSL-SE or FC injectors, RX8 injectors fit right in place, are inexpensive and will work much better for you. The old school low impedance, pintle style injectors will require resistors to work with the MS, will never perform as well, and are prone to sticking, you are so much better off without them.

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10 minutes ago, mhr650 said:

Here is another big tip for you guys, don’t waste time working with GSL-SE or FC injectors, RX8 injectors fit right in place, are inexpensive and will work much better for you. The old school low impedance, pintle style injectors will require resistors to work with the MS, will never perform as well, and are prone to sticking, you are so much better off without them.

 

Yup, I have run all new GM sensors and switched to 4x420cc rx8 injectors.  A lot of work up front but hopefully will make future maintenance easy.

Edited by Alex3000
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7 hours ago, Alex3000 said:

 

Thanks for this.  There is A LOT I would do differently the second time around.  But I think that's true of life in general.

 

Also, in my head, the wiring portion of this project was to be a negligible expense... 10 trips to pepboys later I spent about $400 bucks this weekend between 35' of battery cable (Sure, move the battery to the back, oh yeah weight distribution, oh yeah) and then drawing everything out on paper (wait i need HOW MANY relays!).  You want HOW MUCH for those shitty Chinese fake copper terminals?!!!

 

Also, I budgeted like one day for wiring. Run some wires, what's the big deal? Let's just say I have adjusted my timetables.

 

This story sounds familiar. When I Squirted the Alfa my plan was to mod the existing harness. I'm glad I changed my mind and bought the DIYAutotune harness instead. FWIW in the DIY harness the hall signal wire is the only one shielded.

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17 hours ago, mhr650 said:

Here is another big tip for you guys, don’t waste time working with GSL-SE or FC injectors, RX8 injectors fit right in place, are inexpensive and will work much better for you. The old school low impedance, pintle style injectors will require resistors to work with the MS, will never perform as well, and are prone to sticking, you are so much better off without them.

 

I have the RX8 injectors on their way, ordered at the same time as the MS.  GM sensors are ordered as well but I haven't decided on a path forward on coils yet.  I know the LS1 coils are a popular option but I've also read that the FC trailing coils are what a lot of FD guys are swapping in.  

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20 hours ago, Alex3000 said:

 

Thanks for this.  There is A LOT I would do differently the second time around.  But I think that's true of life in general.

 

Also, in my head, the wiring portion of this project was to be a negligible expense... 10 trips to pepboys later I spent about $400 bucks this weekend between 35' of battery cable (Sure, move the battery to the back, oh yeah weight distribution, oh yeah) and then drawing everything out on paper (wait i need HOW MANY relays!).  You want HOW MUCH for those shitty Chinese fake copper terminals?!!!

 

Also, I budgeted like one day for wiring. Run some wires, what's the big deal? Let's just say I have adjusted my timetables.

Welding ground cable is usually cheaper and WAY better than the automotive battery cable FYI.

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On 7/13/2018 at 1:02 AM, shanehutton said:

I would be more concerned with a VR sensor.  The Hall should be fine.

 

Double check your jumpers etc.  Make sure you have checked to see if you will need a pull-up resistor.

 

Is it an OEM Hall or aftermarket like Cherry etc?

 

I did pretty extensive testing with the JimStim (ecu stimulator board) and checked most of the signals with an oscilloscope.  Fingers crossed it all seemed to be working how it should.

 

Hall sensor is the one sold by DIYautotune (company that sells the megasquirt) so it should be optimally compatible.  It has internal pull-up so no need to worry about that.

 

Another 20 hour wiring weekend and I'm very close to finishing up the wiring.  On the plus side my soldering skills have improved 100x over the past few weeks 🙄

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Which Hall from DIY Autotune?  If it is the red one with the threaded body it will likely need a pull-up.   It's made by a company called Cherry.  They are fantastic and have never had an issue with one in multiple applications.

Sounds like you are having fun with the build and install.

 

 

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