3-wire Knock Sensor vs 2-Wire Knock Sensor?

For discussing how to choose sensors and create a wiring harness for all Bowling and Grippo versions of the MegaSquirt® EFI controller.
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Southcross
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3-wire Knock Sensor vs 2-Wire Knock Sensor?

Post by Southcross »

I have to be missing something somewhere....

:RTFM:
I'm looking into wiring a Knock Sensor into my MSII v3.57... I found a Knock Sensor amplification part called Knocksense and also I find Diagrams for making my own amplifier. What I can't figure out, I already have a knock sensor, but its 3-pin (stock VW). Everything else (unit and diagram) is for a 2-pin Knock sensor. What am I missing?
1979 Volkswagen Dasher MegaSquirted Turbo Drag Project a.k.a Mr Hanky
gofastant
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Posts: 46
Joined: Sun Oct 09, 2005 12:01 pm
Location: Maine

Re: 3-wire Knock Sensor vs 2-Wire Knock Sensor?

Post by gofastant »

Southcross wrote:I have to be missing something somewhere....

:RTFM:
I'm looking into wiring a Knock Sensor into my MSII v3.57... I found a Knock Sensor amplification part called Knocksense and also I find Diagrams for making my own amplifier. What I can't figure out, I already have a knock sensor, but its 3-pin (stock VW). Everything else (unit and diagram) is for a 2-pin Knock sensor. What am I missing?
The 3rd wire is for the shield (grounded) so it's essentially a 2 wire.
Southcross
MegaSquirt Newbie
Posts: 17
Joined: Mon Dec 27, 2004 5:58 pm
Location: Colorado, USA
Contact:

Re: 3-wire Knock Sensor vs 2-Wire Knock Sensor?

Post by Southcross »

gofastant wrote:
Southcross wrote:I have to be missing something somewhere....

:RTFM:
I'm looking into wiring a Knock Sensor into my MSII v3.57... I found a Knock Sensor amplification part called Knocksense and also I find Diagrams for making my own amplifier. What I can't figure out, I already have a knock sensor, but its 3-pin (stock VW). Everything else (unit and diagram) is for a 2-pin Knock sensor. What am I missing?
The 3rd wire is for the shield (grounded) so it's essentially a 2 wire.
Wiring to the Knock sensor, I only have the single core-shielded wire. So would it be acceptable to wire the pins 2 & 3 to the shield right from the sensor? Or would I need to find a dual-core shielded wire, then join 2 & 3 at the knock box??
1979 Volkswagen Dasher MegaSquirted Turbo Drag Project a.k.a Mr Hanky
gofastant
Helpful Squirter
Posts: 46
Joined: Sun Oct 09, 2005 12:01 pm
Location: Maine

Re: 3-wire Knock Sensor vs 2-Wire Knock Sensor?

Post by gofastant »

Southcross wrote:
gofastant wrote: The 3rd wire is for the shield (grounded) so it's essentially a 2 wire.
Wiring to the Knock sensor, I only have the single core-shielded wire. So would it be acceptable to wire the pins 2 & 3 to the shield right from the sensor? Or would I need to find a dual-core shielded wire, then join 2 & 3 at the knock box??
I'm not familiar with the difference between single or dual core shielded wire but I would leave the shield entirely seperate from the circuit. The shield's purpose is to absorb stray electro-magnetic fields and bring them to ground. You don't want that interference in the signal.
Southcross
MegaSquirt Newbie
Posts: 17
Joined: Mon Dec 27, 2004 5:58 pm
Location: Colorado, USA
Contact:

Post by Southcross »

uhm... the Shield IS the sensor ground on the 2-wire knock sensors. The 3-wire litterally has two grounds... I question if one is just a sensor ground and one is just a shield, or are they both the sensor ground and need "fused" together at some point before the knockbox?
1979 Volkswagen Dasher MegaSquirted Turbo Drag Project a.k.a Mr Hanky
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