Cylinder head temp sensor with EFI...

[JLaw]

Hi,

Wondered if anyone is using a CHT sensor for warm up enrichment on their VWs rather than the oil temp sensor. Seems a better idea to me but unsure which thermocouple to use..

Cheers,

John.

[Martin S.]

Yes I am using one from an air cooled VW same as factory EFI does.

VW BOS-0-280-130-012 - HEAD TEMP SENSOR BEETLE 75-79 / TYPE 3 68-73 / BUS 74-79 / VANAGON 80-83
https://www.cip1.ca/ProductDetails.asp?ProductCode=BOS%2D0%2D280%2D130%2D012

Mine is screwed into the head just below the #2 Plug and I can remove it with the engine in the car.
Friend of mine has his somehow mounted to the valve cover so I suppose it can go anywhere hot.

Coincidentally, my car started running like absolute crap last fall, missing and stalling.
Turns out the used sensor that was on there was intermittently shorting internally.
This made the ECU think it was 40 below on and off.
I replaced the sensor with a fixed resistor and the problem instantly went away.

Solved! 

[JLaw]

Hey thanks for the info, can you connect the sensor directly to the ecu or does in need a controller or amplifier? I'm considering using the bosch sensor that Porsche use for the 3.2.

https://www.ebay.co.uk/itm/Porsche-911-carrera-targa-Temperature-Sensor-Cylinder-Head-OEM-Bosch-/361466050593

Cheers.

[JLH]

I would recommend using a 2 pole sensor (like the Porsche/Bosch) so you can connect signal/5V and sensor ground/ECU ground to ensure  that your ECU don't see any ''false'' values. I'm New to this EFI stuff my self, but one thing i have learned is that every type of sensor the ECU want to read information from should have sensor ground through the ECU and not ''engine ground''.

Just a input, I can be wrong.

 

I'm running a ''coolant'' type sensor (two pole) screwed in to the head at cyl3 and works fine for me. As you say, basically you just need it for WUE.

[Martin S.]

Good point about the two-wire sensor vs. one-wire, although the one-wire one I'm using is on millions of VWs and works fine with just the one wire.
In my Electromotive manual they give the resistance vs. temperature data for the sensor so you can check whatever one you use.
The dashboard screen shows the CLT temperature which should read ambient when the engine is cold so make sure that reads correctly.
There is no preamp between the sensor and the ECU and in my case it is one wire, pretty simple.
Like I said, you can swap a fixed resistor in place of the sender and the engine will run fine but lack some warm up enrichment for a few minutes sort of like running your Webers without a choke. We know that works fine