Default cable to VR sensor from Ford not shielded !?

Patriq · Post by **Patriq** » Tue Oct 02, 2007 8:14 pm

I bought a complete package from triggerwheel.com with sensors, coils, EDIS-units, harness etc.

Now that I'm installing it in the engine bay I notice that the cable that came with the VR-sensor (which is from a Ford) - it is not shielded.
I thought it would be.
Now, I concidere this solved, since where I assemble it with the harness to the EDIS-unit i cover the joint with a crimp-boot. And I have one that is shielding - and now I've covered the whole of the cable from the VR-sensor with it. And I'm simply joining this crimp-boot with the shielding that is in place on the harness from the EDIS-unit.

This should do it - shouldn't it?
And isn't it strange that this cable isn't shielded in the first place ?

MartinM · Post by **MartinM** » Wed Oct 03, 2007 8:52 am

I've just looked at two of my VR sensor cables - both OE Ford.

One is shielded, one isn't.

Maybe:
- Ford decided that shielding was needed in some cars' installations, but not others, depending on the routing of the cable
- early ones were not shielded and there were problems so later ones were
- early ones were shielded but the bean counters decided that no shield was cheaper

Without knowing exactly how the VR signal is handled inside the EDIS, it's difficult to say how susceptible it is to electrical noise. It is a low frequency ac signal where the only important thing is the "zero crossings" - it's feasible that some simple electrical filtering in the EDIS could make it fairly immune to interference - unlike the PIP and SAW signals which are digital in nature and more susceptible to interference, and hence run in shielded cable

Having said that, I wouldn't run the VR sensor cable (either type) directly across the plug leads!

What you've done is probably on the cautious side, but at least it means that you should be able to eliminate VR sensor cable noise pickup if you have any problems...

Patriq · Post by **Patriq** » Wed Oct 03, 2007 10:52 am

Ok, thanks.

I'll avoid the plugleads. I have the EDIS-unit and the coilpack just about smack up to each other. This means that the cable from the VR-sensor comes at one point at a distance of say 10-15cm of the plug leads. Do you think that will be a problem ?

MartinM · Post by **MartinM** » Wed Oct 03, 2007 12:17 pm

10-15cm, coupled with the earthing shield you've put on the VR cable will almost certainly be fine - but don't take me to court if it's not

Patriq · Post by **Patriq** » Wed Oct 03, 2007 12:49 pm

Ok, that's good enough for me.

Thanks again !

mwman · Post by **mwman** » Tue Oct 09, 2007 10:31 am

I work in the Avionics industry, I used twin twisted shielded wire (red / blue wires braided shield) we use for audio in aircraft.
It is flame retardant / heat resistant and half the diameter of the Ford cable. Check your local aircraft parts store, in England Adams Aviation Biggin Hill should be able to help, or just give a aircraft maintenace company a call.
I also de-pinned the EDIS connectors and fitted the new wire directly, I hate terminal blocks!!

Simon

Patriq · Post by **Patriq** » Tue Oct 09, 2007 11:27 am

mwman wrote:I work in the Avionics industry, I used twin twisted shielded wire (red / blue wires braided shield) we use for audio in aircraft.
It is flame retardant / heat resistant and half the diameter of the Ford cable. Check your local aircraft parts store, in England Adams Aviation Biggin Hill should be able to help, or just give a aircraft maintenace company a call.
I also de-pinned the EDIS connectors and fitted the new wire directly, I hate terminal blocks!!
Simon

You soldered the edis connection directly ? Personally I'd prefer to have the EDIS unit securely fastened in the engine bay and still being able to remove the wiring.

I use a flame and heat resistent cable too. It's for automotive use though.
I think I used the same for GPS signals on the glider I used to own. So the automotive cable came to use in aviation too.

mwman · Post by **mwman** » Tue Oct 09, 2007 12:03 pm

Hi Patriq,
No you misunderstood what I said, I have taken the pins out the EDIS plug, removed the old wire and re-used them.
I did not want to solder /sleeve the old wires, looks much better!

Simon

Patriq · Post by **Patriq** » Tue Oct 09, 2007 1:22 pm

mwman wrote:Hi Patriq,
No you misunderstood what I said, I have taken the pins out the EDIS plug, removed the old wire and re-used them.
I did not want to solder /sleeve the old wires, looks much better!

Simon

Yes,
sorry - I misread you.
Yeah - that would like much cleaner.

alexander · Post by **alexander** » Thu Jan 24, 2008 12:55 am

just to emphasise a point touched on by simon, twisted pair cables are twisted specifically because the twist reduces the effect of EMI on the twisted wires. you will note that this is, for example, the world standard for telephone cabling. it is an alternative to foil and braid shielded cablel; easier to work with, and more flexible. not that i gave that a moments thought when i wired up my loom with shielded cable! using proper twisted pair cable may be a better alternative; i found the soldering the shield and earthing it a bit of a pain; i also note that if you use braid shielded cable, you have to be really careful that you dont let a single little strand of the braid touch the inner core, when joining to connectors, as that would short the signal to ground.

alexander.

TwoSheds · Post by **TwoSheds** » Fri Jan 25, 2008 1:29 pm

After reading (above) that the earthed sheath may not be necessary with twisted pair, I was wiring mine temporarily (using castle connectors) just to check the polarity of the VR connections, and I didn't bother earthing the sheath. After two hours of checking everything I could think of, and getting no spark at all, I finally earthed the sheath on the VR wire and BINGO - big fat sparks visible even in sunlight!

I say buy the sheathed stuff and use it

TwoSheds

Dimbit · Post by **Dimbit** » Fri Jan 25, 2008 9:11 pm

My EDIS and VR sensor came from different cars. The EDIS tail is shielded, the VR end isn't.
I plan to use a plain twisted pair unless I can find a scrap of shielded 2-core lying around.

alexander · Post by **alexander** » Fri Jan 25, 2008 10:38 pm

well..... shielded twisted pair is a cable standard - if you can find where to buy it in 2m lengths! - so maybe that is the go!

alexander.

Dimbit · Post by **Dimbit** » Fri Jan 25, 2008 11:25 pm

by plain twisted pair I meant the kind you get when you mix a pair of wires and a drill. I've used that trick to get signals out of moderately noisy places before. I'm sure it'll be fine for testing at least.

alexander · Post by **alexander** » Sat Jan 26, 2008 4:21 am

oh i only meant that you can buy shielded twisted pair - if you can find where - which would protect from EMI in 2 ways.
i am sure that it makes no difference how twisted pairs become twisted, so your suggestion is very cost effective indeed..

regards
alexander.