2 S's & a clubman wrote:
All the vacuum hoses have been replaced since i've had it, still crap economy either way.
Doogie
Well. . . if you're sure
The MAP sensor line was a fair bastard to seal in my case. . .
If you want a crude (but effective none the less) test to see whether the MAP sensor is working, then while the car is idling unplug the vac line from the ECU, block the end going to the manifold and see what the idle speed and engine note does. If it doesn't change, then there's a problem with either the sensor or the line. If you then hook up a vac line to the ECU and apply vacuum (suck on the pipe

), the engine note should change if the MAP sensor is working. . .if not, it's probably stuffed - in which case, it's new ECU time. If the engine note does change with sucking, then there must be a leak in the manifold to ECU line somewhere. .
As Mokesta said, it could also be a dud coolant sensor. . .this is on the bottom of the inlet manifold and changing it is probably the single most difficult job you can do on a Mini without removing the motor. . .
Air temp sensor doesn't seem to make much difference - when we bought our Cooper, it had a K&N cone filter with no provision for the air temp sensor so, in true Japanese 'tuning' style, it was left dangling in the engine bay. After putting the original air box (and sensor) back on. . .there was absolutely no difference in ease of starting, drivability or fuel economy. . .