what does it do and could it cause the car to over fuel if broke.cheers

 

On a rst??? If it the one in the cross over pipe it a temp sensor for inlet charge,too high a temp and you'll hit overboost.
Overfuelling could be as simple as bad/incorrect setup or even thermotime switch/temp sensor(the blue one under the inlet manifold)

 

obviously it measures the temperature of the incoming charge air. that informaion is needed by the ecu to calculate the density of the air, so it knows how much fuel to put with it (this is based on mass, not volume). without it, for safety of the engine, the ecu has to assume that the air is at it's densest (i.e. coldest) and add fuel accordingly. that means that at higher act's it will be overfuelling.

that is the safe way, but i'm not saying that all ecu's and maps are programmed that way. as you don't say what you're talking, who can say for sure?

 

HI,

ACT sensor, on the signal to the ecu alters the fueling and ignition
also covers operation of turbo boost pressure. above 70degrees(C) approx.

DAVE R.