Typically when a MAF fails , unplugging it actually makes car run better.

 

The error you have now 

 

17705 Pressure drop between turbo and throttle valve P1297 (check dv)

 

Could be either:

DV

N75 Valve

Boost leak / split hose

 

Old DV should not be cleaned with anything but thrown in the bin.

 

The new style OEM DV has a better diaphragm and stronger made. It is the best leak free DV available, so i would recommended getting new one if you have never replaced it. 

 

These cars are getting on a bit now so converting hoses and pipes over to silicon or getting oem is worthwhile.

 

Thanks for the detailed answer. I have no documentation that the dump valve has ever been replaced. The cars is now at 142k miles.

 

Will I only know if the dump valve was the cause by replacing it with another one? Are there any tell-tale signs that it's the probem?

 

(haven't taken off a dump valve before so not sure what to look for).

I have a spare oem dv somwhere you an have

I have a spare oem dv somwhere you an have

Cheerss Daryl, that would help me a lot. PM on the way : )