FiTech tach wire shielding

I know this has been posted on here before, but I can't find the thread after many board and Google searches. What's the best way to shield the wire? I'm getting the "RPM noise" code, and since that's a very common problem, I figured I'd start there. Sorry for the repost. Thanks!

What I did with my old Holley TBI was use 2 conductor shielded cable spliced as close to the pick-up as I could and made sure the foil shield was long enough to cover the splice flush to the pick-up. I could not get a usable tach signal until I did this.

Most of the noise is inside the distributor from the spark jumping from the rotor to the towers.

MSD sells a 6'cable with their ends on it. If your distributor doesn't have
shielded pick-up wires you could just cut off the plug and splice it in like I said. The stuff can be hard to find unless you want 500 ft of it.

https://www.msdperformance.com/products/accessories/harnesses/parts/8862

Kevin

The local hardware stores ( Lowes etc ) usually sell shielded telephone or audio cable pretty cheap. We have used it successfully on several EFI, digital dash and other installs were noise can be an issue

isn't that wire a solid core of super small gage ? or isn't that a problem ?

they make it both ways depending on the supplier. The signal is extremely small current wise as well as pulsing so the size is more that adequate

All right, I'll give it a shot! Thanks!!

What you're looking for is twisted shielded pair. For example, Belden 8412. Sometimes just the twisting will work, but the shielding makes it more complete. One end of the shielding is grounded.

Twisting the wire puts the signal on both wires evenly and they cancel each other out. Shielding makes it almost interference proof.

R.

Is this an issue when using the FiTech to control the timing?

It's a common thing. The injectors need a clear signal to fire properly, and if there's any interference, they won't and they'll give an "RPM noise" fault code. I'm not sure if it's more common with timing control or not though.