Hi all I've made a fresh post and going to list everything I have tried and done.
EDIT: I have searched the web for ideas and have found nothing other than what I've already tried.
I have vagcom and VAS main dealer. VAS says p1297 17705 pressure drop between turbo and throttle valve - STATIC. Notice how mine says static, yet the majority of other people with this fault says intermittent. How can it be "static" at idle with no boost and 20 inch vacuum.
Before i go on, the car always runs flat until boost gets to 10 psi (car is mapped) then goes like the clappers, then goes in to limp mode. Sometimes it will jerk as if you are jabbing the throttle on and off. Sometimes but rarely get backfires while accelerating..
This fault is mainly trial and error. And here is my exhaustive effort to fix this fault:
New genuine maf (x2)
Air intake temp sensor genuine
Coil packs genuine
Spark plugs genuine
Pressure relief valve genuine
Dump valve genuine (now running forge diverter)
Rear lambda/O2 delete
Smoke tested with no leaks (at least into atmosphere)
Minimal play in turbo
Checked timing, intake cam very slightly advanced
Vacuum pipes checked & vacuum holds
Checked pcv valve works as should do
2nd hand genuine fuel pump (reads 3bar with vacuum pipe removed from FPR)
New fuel filter genuine
Replaced fpr several times making sure o-rings are not damaged
cleaned and realigned throttle body
Injectors read 12.7 ohms
Injectors appear to have identical spray pattern
Cleaned earths under battery and on coil pack loom
New boost pipe genuine
Engine oil flush with SPX refilled with 5w-30 long life 3 genuine oil and genuine filter
Replaced both solenoid valves on intake manifold (n249 and what ever the other one is)
New y shape breather hose
New pipercross air filter
Tried a 180bhp ecu, fault and symptoms remain the same.
VAGCOM logs look ok, nothing out of the ordinary. Will do more if requested.
No rich/lean fault codes
Someone please help before I burn the car in anger lol..