BWA K04 Gti Extremely underpowered please help

[aarondsg]

Wondering if anyone can help me please or point me in the right direction.
I have a GTI k04 convert with all stage 2+ mods have the printout from back in october 2013! used to be 360bhp 387ft lbs done at rtech

the car now is extremely underpowered and the turbo is quite laggy
i did do some data logs and the boost appears to be all over the place..
at one point at 3680 rpm the car requested only 2200mb but hit 2510mb
then another time at 4000rpm requested 2270mb hit 2510mb
at 3480mb it requested 2210mb 1390mb
sometime even at like 4-5k its not hitting no way near the requested boost sometime over half a bar less and sometimes overboosting from the actual specified.

turbo sometimes doesnt kick in till 4000rpm and does not perform anything like a k04 car should!
i did log some other blocks and can log any additional if they may help someone to point me in the right direction.

thanks in advance

[rich83]

Fault codes?

[aarondsg]

000257 - Mass Air Flow Sensor (G70)
P0101 - 001 - Implausible Signal - Intermittent
012555 - Low Pressure Fuel regulation
P310B - 002 - Fuel Pressure Outside Specification - Intermittent
000665 - Boost Pressure Regulation
P0299 - 002 - Control Range Not Reached
000313 - Oxygen (Lambda) Sensor B1 S2
P0139 - 004 - Response too Slow - Intermittent
004372 - Oxygen (Lambda) Sensor; B1 S2
P1114 - 008 - Internal Resistance too High - Intermittent
004688 - Fuel Level too Low
P1250 - 008 -
000406 - Engine Oil Temp. Sensor (G8)
P0196 - 004 - Implausible Signal - Intermittent

these was codes i had before but my alternator had died and records as low as 10volts!

i cleared the codes today and went out for a blast and these are the only following codes that exist now ;

000257 - Mass Air Flow Sensor (G70)
P0101 - 001 - Implausible Signal - Intermittent
012555 - Low Pressure Fuel regulation
P310B - 002 - Fuel Pressure Outside Specification - Intermittent
000665 - Boost Pressure Regulation
P0299 - 002 - Control Range Not Reached - Intermittent
000313 - Oxygen (Lambda) Sensor B1 S2
P0139 - 004 - Response too Slow - Intermittent

005634 - Power Supply Terminal 30
P1602 - 002 - Voltage too Low - Intermittent

the following are the codes that come up after a blast
temperatures on the log between 79deg and 84deg

[xjay1337]

Some basic googling will tell you the faults.
which is what most of >us< who "appear to know everything/a lot" do...we just search and pick the right information out.

p0299  is nearly always diverter valve... so buy a new revision g anyway .
p0101 is what it says.. MAF sensor faulty... HOWEVER this can also present with boost leaks.. have you checked all your boost hoses?

[aarondsg]

thanks
it does have a g in there
and its not split at all even underneath the diaphragm.
i also tried another maf and still to no avail.
i have visually checked boost hoses nothing visually showing im trying to source somewhere i can have a boost leak smoke test done.
is there anywhere prone to boost leaking on these ?

[xjay1337]

OK well the car's not meeting the requested boost. giving underboost error. so you have a boost leak or a f**ked turbo. (i'm guessing. i'm not a mechanic).

have you checked every boost hose and connection? there's one coming out the back of the turbo, pancake pipe, tb and of course the lower radiator ones.