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FiTech tach wire shielding #2354596
08/16/17 01:15 AM
08/16/17 01:15 AM
Joined: Feb 2003
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Laveen, Arizona
GTSDart340 Offline OP
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GTSDart340  Offline OP
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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!


1949 International KB-2 "Mater" - 302/T5

1968 Dodge Dart GTS "The Drat" - 340/727

2006 Dodge Magnum R/T - Hemi

2016 Dodge Durango Limited - 3.6
Re: FiTech tach wire shielding [Re: GTSDart340] #2354613
08/16/17 01:41 AM
08/16/17 01:41 AM
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Downtown Roebuck Ont
Twostick Offline
Still wishing...
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Downtown Roebuck Ont
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

Re: FiTech tach wire shielding [Re: GTSDart340] #2354841
08/16/17 01:41 PM
08/16/17 01:41 PM
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Omaha Ne
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TJP Offline
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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

Re: FiTech tach wire shielding [Re: TJP] #2355409
08/17/17 12:22 PM
08/17/17 12:22 PM
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north of coder
moparx Offline
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north of coder
isn't that wire a solid core of super small gage ? or isn't that a problem ?
beer

Re: FiTech tach wire shielding [Re: moparx] #2356048
08/18/17 02:03 PM
08/18/17 02:03 PM
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Omaha Ne
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TJP Offline
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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

Re: FiTech tach wire shielding [Re: GTSDart340] #2356072
08/18/17 03:03 PM
08/18/17 03:03 PM
Joined: Feb 2003
Posts: 1,306
Laveen, Arizona
GTSDart340 Offline OP
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GTSDart340  Offline OP
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All right, I'll give it a shot! Thanks!!


1949 International KB-2 "Mater" - 302/T5

1968 Dodge Dart GTS "The Drat" - 340/727

2006 Dodge Magnum R/T - Hemi

2016 Dodge Durango Limited - 3.6
Re: FiTech tach wire shielding [Re: GTSDart340] #2356082
08/18/17 03:14 PM
08/18/17 03:14 PM
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dogdays Offline
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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.

Re: FiTech tach wire shielding [Re: GTSDart340] #2356200
08/18/17 07:30 PM
08/18/17 07:30 PM
Joined: May 2005
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Florida
BDW Online content
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BDW  Online Content
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Florida
Is this an issue when using the FiTech to control the timing?

Re: FiTech tach wire shielding [Re: GTSDart340] #2356336
08/19/17 12:46 AM
08/19/17 12:46 AM
Joined: Feb 2003
Posts: 1,306
Laveen, Arizona
GTSDart340 Offline OP
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GTSDart340  Offline OP
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Laveen, Arizona
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.


1949 International KB-2 "Mater" - 302/T5

1968 Dodge Dart GTS "The Drat" - 340/727

2006 Dodge Magnum R/T - Hemi

2016 Dodge Durango Limited - 3.6






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