Its one of three together and its the one on the right hand side looking from the front of the car.
Glynn
Glynn
there isnt one, its all built into the black vacuum control box at the back left of the engine bay, you will see the vacuum pipes go into it, for both n18 and n75.
Slugger
Guest
There seem to be two identical ones? Is it one of those? They are attached to the firewall bit right at the back and are towards the right but not as far over as the MAF sensor
Thanks!!
Thanks!!
Okay, heres an annotated underbonnet view of a TDI 110 that I have used in several threads now (although it isn't original to me, and I can't remember who I copied it from now).
For completeness, I should add that the sensor assembly in the pipe from the intercooler at 12, labelled IAT (Inlet air temperature) also houses the MAP (manifold air pressure) sensor (NOT to be confused with the MAF - Manifold air Flow sensor, which is labelled 4) This makes sense, as you want to know the temperature and pressure of the charge going to the cylinders, after the intercooler.
I don't think the colour of the vacuum switch elements is a reliable indicator of their function, as there is no difference between the two in what they do, just that one is connected to the EGR and the other to the turbocharger inlet vane control.
For completeness, I should add that the sensor assembly in the pipe from the intercooler at 12, labelled IAT (Inlet air temperature) also houses the MAP (manifold air pressure) sensor (NOT to be confused with the MAF - Manifold air Flow sensor, which is labelled 4) This makes sense, as you want to know the temperature and pressure of the charge going to the cylinders, after the intercooler.
I don't think the colour of the vacuum switch elements is a reliable indicator of their function, as there is no difference between the two in what they do, just that one is connected to the EGR and the other to the turbocharger inlet vane control.
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Slugger
Guest
Thats fantastic! I have been searching for ages looking for something like that but couldn't find it for the life of me!
So I assume the N75 and N18 are not identical in what they do so you need to make sure you buy both if you wanted to replace both?
So I assume the N75 and N18 are not identical in what they do so you need to make sure you buy both if you wanted to replace both?
Well, both look the same and perform the same basic task, pneumatic switching. Two pneumatic "fixed" inputs, atmospheric pressure (from the airbox) and vacuum (from the vacuum pump and reservoir), one output, taking a variable pressure to the actuator. Each has an electrical input from the ECU which works the valve to vary the output pressure. They have the same outline, fixing and general shape, so in theory they should be interchangable.
However they have different part numbers, and as ssstew has noted, different colours of cap. I don't know for sure if there are internal differences.
However they have different part numbers, and as ssstew has noted, different colours of cap. I don't know for sure if there are internal differences.
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