Audi B4 external temperature

[spyros80]

Hello,

Recently I put an external temperature gauge on my Audi 80. Since then Iam facing out some problems as it does'nt show the right values. I connected the lights, the ignition, the sensor, the white/blue speed signal wire and the earthing but still the gauge keep rising (not fast but slow) when the car is moving. I put the sensor behind the left front bumper grill, I bought a new sensor in case it is faulty, I put the wires in a cool place within the engine room but still the problem remains. What should I do more?
The only thing I have left to change is the gauge monitor in the instrument cluster. Any suggestions would be very helpful

[anton]

How much does the value go up by?? i wouldnt be surprised if the air arount that area does get hotter with the engine running as its not too far from the intercooler?? could be wrong...try putting it between the inner and outer wings perhaps??

Ant

[spyros80]

b4 external temperature

For example. when I pick up the car in the morning, it shows the real value let;s say 22 C. When the cars temperature goes to 90 degrees, the sensor shows 33 C, value which I thing is not right!
Lately, I see also that when I turn off the ignition and turn it on again the sensor shows 44 or 51 C and drops until 33C. And that's all it never drops more. I don't really know what' s happening. And I can't also find where AUDI put the wires from the construction. Any ideas will help.

[johne]

Looks to me that it's the position of the sensor that's causing the problem.

The sensor wants to be somewhere that gets the outside air blown over it as the car moves without being behind any heat source such as the radiator or intercooler.

Audi mount the sensor on a bracket 100mm in front of the radiator, about 1/3rd up from the bottom of the radiator. Even with the sensor mounted where Audi put it, the temperature will be higher if you return to a warm car and take a few minutes of driving to go down to the real outside temperature.

If you want to test the sensor, put it in a glass of ice, salt and water and after a few minutes the display should read very close to zero.

[spyros80]

external temperature

Dear Johne,

Do you know where the cables are driven within the engine compartement? Or do you have any photo to show me?

[johne]

The cable is part of the wiring loom and comes out at the same point as the headlight cable.

DSCN1285.JPG

It's very difficult to get a good picture of the sensor as it's down by the bottom hose. In this picture you can see the sensor in the middle mounted on a right angle aluminium bracket which shows a little corrosion. It's above and to the right of the bit of red cable showing. The connector on the left with the brown tie-wrap holding it to the body is the temperature sensor connector.

[spyros80]

b4 external temperature

Thank you very much for your precious help