Engine Ambient Air Temperature Sensor

[Mirez]

Can someone give me the wherabouts of it? I've got some sporadic readins from it recently so think it neeeds checking out but can't find the thing - I was expecting it to be on the same pipework as the MAF but there is no other circuits there and only the one cable (MAF) in the vacinity. Is it built into the MAF by any chance?

[insider]

I think it's probably the T-MAP sensor you want (item 6), on the opposite side of the engine to the MAF sensor (item 10).

 

[Mirez]

Many thanks!, Thats a very handy diagram :rolleyes:

 

I can't see that one reading ambient though, surely thats manifold temperature? Which in fairness would make more sence since outside temp was 6*c last night but the "ambient" temperature I had showing was anything between 19 and 36...

[insider]

The T-MAP sensor measures the intake air temperature, i.e. ambient air temperature.

On other cars a T-MAP (Temperature and Manifold Absolute Pressure) sensor replaces both the MAF (Mass Air Flow) and IAT (Intake Air Temperature) sensors. However, for some reason the VW diesel engine has both a MAF and a T-MAP.

[insider]

The T-MAP sensor measures the intake air temperature, i.e. ambient air temperature.

On other cars a T-MAP (Temperature and Manifold Absolute Pressure) sensor replaces both the MAF (Mass Air Flow) and IAT (Intake Air Temperature) sensors. However, for some reason the VW diesel engine has both a MAF and a T-MAP.

 

Just realised why - the MAF sensor measures the air flow before it reaches the turbo.

The T-MAP sensor measures air pressure and temperature after the turbo to enable boost pressure and fueling to be accurately determined.

So, it won't be measuring the true ambient air temperature, perhaps this is just VAG-COMs definition of ambient temperature?