Ambient temp reading (1 Viewer)

[Lofty1]

Since we bought our ducato (used) the outside temp has remained at 0" A quick look up told me the sensor is in the o/s mirror, on checking it was not ,must have had a mirror change. Being to tight to buy a new mirror I bought a thermistor off ebay £2.80 wired it into the mirror arm, drilled a little hole in the plastic and it all works.

Ps checked the n/s mirror found that had also been changed and new one had no radio aerial so that is the next job.

 

[Bognor Saint]

Our ambient temp readings have gone berserk recently. We get readings varying between -87 and +92. Occasionally there will be a "warning ice on road" message. We are still under dealer warranty and they are sending MH to Fiat for a fix.

 

[Lorryman100]

A point worth considering is that not all vehicles with an internal outside temp gauge have an independent sensor fitted externally. As part of the fuelling strategy within the EMS (engine management system or ECU) it utilises the MAF/T (manifold air flow/temperature) sensor to tell it the ambient air temp coming into the engine on the induction side. This can then be displayed by the instrument cluster as the outside air temp, the EMS and IPAC communicate over the CANBUS. If you use an OBD diagnostic tool that displays live data then the Ai (air intake) temp is taken from the MAF sensor. It is important for the EMS to know the intake temp as colder air is denser than warm air requiring less fuel in the burn.

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[nicholsong]

A point worth considering is that not all vehicles with an internal outside temp gauge have an independent sensor fitted externally. As part of the fuelling strategy within the EMS (engine management system or ECU) it utilises the MAF/T (manifold air flow/temperature) sensor to tell it the ambient air temp coming into the engine on the induction side. This can then be displayed by the instrument cluster as the outside air temp, the EMS and IPAC communicate over the CANBUS. If you use an OBD diagnostic tool that displays live data then the Ai (air intake) temp is taken from the MAF sensor. It is important for the EMS to know the intake temp as colder air is denser than warm air requiring less fuel in the burn.

Is not the air being sucked into the manifold not subject to a Venturi effect, thus reducing the pressure and therefore the temperature of the air at that point?

 

[Lorryman100]

The MAF sensor is located in the air filter box pipe work usually after the filter depending on what type of sensor, enclosed hot wire or open hot wire. The manifold sensor is the MAP (manifold absolute pressure) sensor which also has a temperature probe as the air will be considerably warmer than ambient temp by the time the turbo compressor has compressed the air volume even after passing through an inter cooler.