Strange boost problem

[CupraSteve]

the last two days my car has been boosting a little odd.

Bascially if i put it in a high gear and floored it it would boost round to above 20psi stay there for about a second then fall to about 15/16/17 depending on gear.

Now its boosting round to about 17/18 then falling straight back down to 15/16/17

it doesnt appear to be holding less boost at the top of the revs but the initial surge is less.

Any ideas? could this just be the weather at the moment?

VAGCOM showed up an intermiitent fault in the coolant temp sensor. Could this be a cause? car temp is reading correctly and no odd fan activity either

 

[Saul]

coolant temp sensor could cause an issue, MAF logs ok?

could be n75/boost leak, log n75 duty

 

[CupraSteve]

iv tried a new n75 i had kicking around it seemed to be the same.

il log maf although tahts only a few months old.

this happened once before but it settled back again after a day or two, maybe its just the ecu throwing a wobbly