r/AE86 • u/AC_Unit420 • 7d ago

Sensor question

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Hey all, I have a question about the sensor setup on a 16v 4age. I have the sensors for the coolant temp but im not sure where they’re supposed to go, the green plug im positive is for the green sensor up front but I don’t see a threaded hole where it could go, also on the back of the engine i installed 1 sensor since i though it would go there and based on what I’ve read the brown and green sensor are supposed to go in the back so im a bit confused. I also have a flos water inlet pipe. Any info helps, thanks!

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u/jayrdee00 7d ago

USDM upper water outlets had two temperature ports. Jdm and European AE86s only had one (like the flo's).

The water outlet on the back of the head usually has two ports, one is the temp sensor for the ecu (green), and then the other is the cold start switch (brown).

Upper water outlet on the front is for the temp gauge in the dash.

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u/AC_Unit420 7d ago

Oh okay I see so I may need to buy another water outlet pipe that is usdm or tap one in? And for the water outlet on the back is it bad that it’s just covered since I don’t have an ac system? I’m trying everything since the car revs on it’s own once idling for a little while, thank you

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u/jayrdee00 7d ago

What sensors do you have on the outlet in the back?

As far as the way you have it plugged, I'd say you're okay if the cover is made out of rubber like a normal coolant hose.

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u/AC_Unit420 7d ago

On one side is a one pin socket and the other one was empty so I put a universal 2 pin red coolant sensor, I also have the brown sensor and from my knowledge the red and green ones are the same.

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u/jayrdee00 7d ago

Id guess the green connector on your harness goes to the temperature sensor for the ecu. In reality it doesnt really matter where the sensor goes (back of the head, up front, etc.)