if it was for the turbo you would have the engine light on, an over and under boost fault code and be in limp mode.
what is it about the power delivery that you feel is wrong?
edit
its an 03 you should have 3 valves on there for a 110 one for the air doser one for the egr and the turbo but you have one missing
the power delivery will be affected as the egr valve is venting to atmos this is not good and will affect your brakes and power delivery as there is no vac in the system that works with vac, so get a bit of pipe and bit of sum thing solid and a jubilee clip and block it up
the valves are color coded blue for egr, gray for turbo and unmarked for air doser.
the 136bhp engines have the vnt turbo which i think is controlled directly by the ecu with no vac feed but i could be wrong
grasmere59 wrote:My 2003 110 only has 2 valves as it hasn't got an air doser fitted.
Yep, same here - 53 plate 110, but no doser/dozer/thingybob valve.
Turns out it was the EGR hose (someone has obviously swapped the hoses and connectors over - odd, considering both valves work fine!) which was hanging loose - popped it back on, secured it, all sorted, and I now have much better power under 1800rpm - it was a bit of a yawning chasm before the turbo kicked in, now it's a much smoother rise of torque.