[First Bird]

The blue Tach wire can pick up electromagnetic interference and give a bad signal to your ECU.

I bought 1/8” braided metal sleeve to shield the blue wire. The “shield” only works if the sleeve is one continuous piece and is grounded in one - and only one - place. If the shield is grounded in more than one place it does not work right. Loops of interference form (or something like that).
I watched a video showing how much voltage was drained by grounding the braid. Really eye opening.

I cut and removed the blue wire from the factory loom. Put the wire inside the shield. Grounded the shield at the TB.
I crimped and soldered the blue wire and covered the braided blue wire with plastic wire loom. Why? So that the braid couldn’t touch metal anywhere and create a second ground loop.

Then I joined the braided shield on both sides of the connector by crimping it to a short wire that jumps around the connector.

I’m almost done with a FITECH 30002 install. Does this shielding work? I’ll let you know. And if anyone spots an egregious error in my work - let me know.

[Bill Hanlon]

Should work.

Comparing to my '52 GMC is like comparing apples to cumquats, but I have a homebrew HEI that uses a Chrysler 6 cylinder mag pickup mounted in my GMC distributor, wired through 5 feet of shielded 22 gauge twisted pair wire to get to the GM HEI module hidden in an old voltage regulator box. I covered this bundle with heat shrink to make it look like old black wire. The shield is grounded at the voltage regulator only. The coil is a Blaster 2 with a 0.7 ohm primary which is real close to a built in HEI coil. Been working well for 8 years and 35000 miles.

[First Bird]

Thanks Bill.

[krisr]

Shielding does work on single wire applications, but don't ground it at the engine, ground it at the ECU end. If you have 2 or 3 wire sensors that are getting a bit of noise, twist the wires all the way and it'll create a similar shielding effect.

[JLMounce]

When installing these systems with the ECU on the throttle body, best practice is to separate the power related wires to one side of the car and the signal wires to the other side of the car. If wires ever have to cross each other, they should do so at as close to a 90 degree angle as possible.

Taking the time to route and extend these wires as necessary to keep them away from ignition wires and other power wires will typically result in good running without having to add any shielding to any specific wires.

[First Bird]

Thanks for the advice guys. The shielding is grounded on the throttle body mount stud.
I’m finishing install today so don’t yet know if I’ll need to do more wiring.

[Formulajones]

First I've heard of shielding the blue tach wire. Interesting.

I didn't bother with any shielding on either install I did here 3 years ago.

In fact on both installs I'm using a tach signal to run 3 different things on both cars, coming off the MSD box. The Sniper, the factory tach in the car, and the controller for the 4L80E trans that is in both cars. A lot of tach signals

No issues to date, but I also did similar to what JLMounce suggested. All the wires basically come out of the back of the Sniper toward the firewall. I have the main power stuff going off to one side of the distributor and to the firewall heading to the passenger front side of the car where the battery is, and the other stuff like 02 sensor and fuel pump etc... running around the other side of the distributor and down the driver side of the car towards the back. So once they leave the Sniper they really never see each other again. I hid as much of it in the factory wire looms that I could, the rest of it is behind the fender or down in the frame rail where it can't be seen.

Shucks even the TPS wires are hidden along with the Alternator wiring because it was convenient, the alternator harness already runs along the top of the valve cover so it was natural for the TPS wires (2 TPS harnesses on both cars) to drop right into the existing harness and disappear.

No issues with that either, and I'm running old style alternators on both cars with external voltage regulators.

[First Bird]

Thanks for the notes guys. Shielding the blue wire might not have been necessary. I’ll never know. As far as separating the signal and power wires, I didn’t. FormulaJones you wrapped those wires up nice and neat. That’s what I do too. I’m gonna wait till I get this install stable. Too many times I’ve fully mummified some install and then had to fight back into my good work to pull a part out.

[Formulajones]

Originally Posted by First Bird

Thanks for the notes guys. Shielding the blue wire might not have been necessary. I’ll never know. As far as separating the signal and power wires, I didn’t. FormulaJones you wrapped those wires up nice and neat. That’s what I do too. I’m gonna wait till I get this install stable. Too many times I’ve fully mummified some install and then had to fight back into my good work to pull a part out.

I know what you mean, spend all that time making things nice and tidy only to rip back into it for something is a bit disappointing. No one wants that.

Interested to hear more on your progress