Stolen of the Internet..... If you need it putting into words more understandable you'll have to wait for someone more intelligent than me to pop by

An engine's MAP, which stands for manifold absolute pressure, sensor monitors the amount of pressure in the intake manifold, which is where air and fuel are introduced to the engine. The vehicle's throttle body helps to increase or decrease the pressure in the intake manifold by opening or closing a specific amount. The MAP sensor will adjust the amount of fuel versus air taken into the engine, based on its pressure readings.

 

Thanks

 

http://www.ebay.co.uk/itm/Focus-RS-2-5-Mk2-Map-Sensor-/121113025018?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item1c32e619fa
this is it salm,dont quote me on this but i think it fits into the bottom of the intercooler.

 

How would you no if your map sensor was gone.

 

Depends, you will get running issues where it holds back, seems like its missing. I had no running issues, scanguage showed it wasn't reading right

 

http://www.focusrsoc.com/forums/topic/33252-cant-believe-what-a-difference-a-new-map-sensor-makes/page__hl__%2Bmap+%2Bsensor
check this out.

 

running too rich, car idles rough (bouncing up and down) cold and hot weather effects the cars performance ie when cold it is jerky and rough riding when warm feels very flat and sluggish.

i replaced one on my fiesta which corrected a whole host of problems i thought was something else considering the price of them it's a good start in the process of elimination before you start changing throttle bodies and other major components.

 

My throttle is bouncing at the min when I press the clutch in could this be my problem too

 

Kirk i wouldn't really have a clue i can only talk from experience with another car, im still getting to grips with my focus i've not long had it a month yet so im still working out how it all works.

but i can certainly say that with a jumping idle and rough ride at low rpm its certainly the cheapest and best fix to start with when you have running issues with the symptoms mentioned above when nothing is flagged on a diagnostics check.

ECU works in mysterious ways as if a single sensor is playing up the others associated kind of compensate for it. It's only when one completely gives way the others cant cover for it completely so the engine throws a wobbley and behold, the ECU finally realizes that somethings not right and gives you an error message and fault code.

until then the car will drive like a sack of

.

The ECU is too sophisticated sometimes for it's own good!

 

To be honest I think mines been broken for that long I got used to how it ran and in my head it was normal. Don't remember any 'rough' running but now its been replaced its obvious it was down on power

 

It also measures inlet air temperature and sends the signal to the ecu. As the sensor is after the intercooler, the ecu can use inlet temps to control the engine's output.