EGT gauge Wiring

[shelbydave]

Ok. I'm building up the wiring harness for my turbo conversion. the engine that is going in has an egt probe on #4, and the wire went straight from the probe to the gauge. I've heard that these type of probes are sensitive to noise, and they should be kept away from the other electronics. What I'd like to do is incorporate this into my harness, bring it through the firewall in the connector block, and then run it to the gauge inside so it "looks" factory. Have a disconnect at the probe for quick disconnections.
Should I do this, or is it better to keep this a separate straight run? How about if I use a good grounded shield?

Thanks

[shelbydave]

Is this post in the wrong area, or am I travelling in unchartered waters?

[Frank]

I think you will be fine. It is typically the Autometer A/F gauges that have issues. If your EGT wiring has a steel braid over it, then just ground the steel braid. If it does not, go find some and put it over. This will insure no noise makes it on to the lines. Typically EGT probes are ok. If you do have problems, it is typically the gauges power/ground wiring, not the probe.


Frank

[XR Tuner]

You can't use just any old wire and connectors for thermocouples.
You need one's designed for this application.

[looneytuner]

Nordskog uses a shielded yellow wire and "K" plugs. I bought some but lost the link in a computer crash. Mine is set up so I can switch the gauges between cars by just unplugging the gauge.
Yeah I'm cheap and it's also in a custom A pillar that was a pain to make for H bodies.

[shelbydave]

Found this out there... good reading.

Connection problems. Many measurement errors are caused by unintentional thermocouple junctions. Remember that any junction of two different metals will cause a junction. If you need to increase the length of the leads from your thermocouple, you must use the correct type of thermocouple extension wire (eg type K for type K thermocouples). Using any other type of wire will introduce a thermocouple junction. Any connectors used must be made of the correct thermocouple material and correct polarity must be observed.

From this site http://www.picotech.com/applications/thermocouple.html

Has anybody used regular connectors? If so, is the error linear, or non-linear? If it's Linear I can deal with it...

[Tony Hanna]

I know this is an old thread, but there's something else you might want to consider. If you're using an unpowered gauge, then you want to have the cold junction (the connection where the end of the probe leads attach to the jumper wires from the gauge) inside the car. Most of them are calibrated for a certain temperature (75*f for Westach) and wild temperature swings at the cold junction will throw your gauge off a little.