94 850 Splicing Knock sensor wiring

skloon · Post by **skloon** » 20 Sep 2015, 19:56

I am near the end of an engine swap and discovered I misplaced the adaptor for the new style knock sensor - has anybody spliced them or is this just a bad idea

Post by **dosbricks** » 20 Sep 2015, 21:38

I have the updated knock sensor kit on my '96 and can't really see the point in all that tangle of wiring. Also can't speak from experience about doing a splice, but if you solder and heat shrink the connections it ought to work. Wish I could say definitively because of it's location underneath the manifold. Probably you will just have to decide whether or not to go for it.

Post by **abscate** » 21 Sep 2015, 04:50

It's a kHz bandwidth signal so a splice or solder will work fine.

skloon · Post by **skloon** » 21 Sep 2015, 09:32

Thanks, just wondering what can't or shouldn't be spliced ? o2 sensors ?

Post by **abscate** » 21 Sep 2015, 09:53

You don't want voltage drops on O2 sensors but a good soldered splice on an O2 sensor wire would work fine. The heater wires can be spliced easily on the O2 sensors.

Probably some of the CAN bus stuff would get iffy if spliced. There isn't a lot of high bandwidth stuff on autos Im aware of - that could be my ignorance though.

I just spent a month tracking a BMW ATF leak to a hole in the bottle of ATF stored under the hood....LOL.

Post by **regent** » 21 Sep 2015, 11:32

abscate wrote:...Probably some of the CAN bus stuff would get iffy if spliced. There isn't a lot of high bandwidth stuff on autos Im aware of - that could be my ignorance though.

I just spent a month tracking a BMW ATF leak to a hole in the bottle of ATF stored under the hood....LOL.

A lot would get iffy with noise injected (EMI), routing in most cases is vital (don't ask me how I know)

I would like to learn more about your fluid leak troubleshooting approach in this complicated scenario

Post by **BEJinFbk** » 21 Sep 2015, 15:01

Here are some hints:
Look for high quality dual wall Polyolefin shrink tubing with
the heat activated adhesive sealant inside. It's like hot glue.
Keeping moisture out is critical.

ALWAYS get the shrink tube on BEFORE you solder...
( Not that I've ever forgotten that - Just sayin'.

)

Be sure you have a good mechanical connection before you solder.
A tightly twisted and smooth connection, with no stray wire strands.
Use just enough solder to "smooth" out the joint.

If you have a heat gun or a butane soldering iron with
a hot air attachment, that's the way to go with shrink tube.
Sooty, uneven heat shrink can be a problem.

Make it Last!

skloon · Post by **skloon** » 22 Sep 2015, 09:24

ALWAYS get the shrink tube on BEFORE you solder...
Hey have you been watching me ???

Post by **BEJinFbk** » 22 Sep 2015, 20:15

Man, I hate when that happens...

Post by **Ozark Lee** » 23 Sep 2015, 08:17

On the knock sensors make sure that the polarity matches up. They are basically microphones and if there was just one it wouldn't matter. With two however, if the polarities don't match, they get 180 degrees out of phase and they can cancel each other out.

...Lee