Help im stumped!

[Rmachines]

My 115 PD MK4 has been going into limp mode when on the dual carriage way...

i got the code
17965 - Charge pressure control : Positive deviation
P1557 - 35 - 10 - - - - Intermittent

I Cleared it and it was fine,  didnt go on the dual carriage way since so i left it at that.

the other day i took it out and right from startup it had no power, so i checked the codes and
17965 code as above came up,  I know the N57 valve is a problem so i got hold of one with the square connector off an audi, i spliced the connector (presuming it would work the same)  and now there are no codes showing but the car still has no power.  BUT... Once i hit 3000 rpm it perks up and the turbo kicks a bit.

I then unplugged the N57 sensor and the fault showed up and it went into limp. 

So.. The car has no faults now and is NOT in limp mode, but its lacking a lot of power,  Is this because the audi valve is diffrent or do i have another problem??

Any help would be great!

[T_J_G]

Off of Ross-Tech

  17965/P1557/005463 - Charge Pressure Control: Positive Deviation
Possible Symptoms

    * Reduced power output
    * Limp mode

Possible Causes

    * Boost Pressure too High
    * Hoses/Pipes incorrect connected, disconnected, blocked or leaking
    * Charger Pressure Control defective
          o VNT (variable nozzle turbo): nozzles stuck
    * Solenoid Valve for Boost Pressure Control (N75) defective

Possible Solutions

    * Check Hoses/Pipes to/between Components
    * Check Solenoid Valve for Boost Pressure Control (N75)
    * Check / Clean / Replace Charge Pressure Control
          o Check / Clean mechanism for variable nozzles


Maybe replace the N75 with one from VW and check all your boost hoses are in good condition and connected well.

[Rmachines]

All boost pipes seem fine, Im not paying the price VW want for a valve,  just aint gunna happen atm!  But since i have changed the valve the fault has gone so obviously no sensors and finding a fault,  its just got massive turbo lag now!

hmmm 

[T_J_G]

Mabe try find someone breaking a TDI 115 or see if any other TDI parts will fit?

[Steve_PD]

I was getting the same code and going into limp mode, turned out to be an intercooler pipe was half off, so check all your pipes.
Failing that it may be the variable vains are sticking on your turbo, which means new turbo 

[Rmachines]

Im wondering if my turbo has blown to be honnest,  its always been a bit whiney

Anyway now there are no fault codes what so ever... all cleared but there is a megger lack of power!!!

Its not in limp mode,  no faults found.   It seems the turbo will spin up but it feels as if its spinning but no where near enough,  it whines a little bit but there is not that high pressure wooshing noise there should be,  and with that... no power!

I dont think its the pipe work as there is no hissing noises,  i can here the turbo is no longer boosting as it should be.

But the N75 valve is off an audi  (square plug) Not the original VW (roundish plug) So could that valve be causing this....  If its very likely i will look into getting a new one.

Otherwise i would rarther save up for a new turbo 

[Steve_PD]

Sounds like the turbos gone  but check the hoses anyway, and a N75 valve is £35 from vw which is alot cheaper than a new turbo.
Hybrid Turbo conversion 

[Rmachines]

Hm,  I would love to go for the conversion but im skint at the moment... hence not being happy 

Its odd it all started with the boost control positive deviation fault...  and now i changed the valve all faults have gone... But the power loss has started..

Right i dont know much about how the valve system works but looking at diagrams i have tried to bypass it to see if i have my power back.

Please if some one knows how to bypass it correctly let me know   Anyway i took the two top hoses (vac in and vac out) And connected them together (bypassing the valve totally)  So i presume its as if it should be at full boost all the time?!?!   But nothing changed ... still no power.   It doesnt tell me much as i dont know if thats the correct thing to do but it might tell you something?

[Rmachines]

New N75 valve is going on today!   I will see how it goes,  my local parts dealer said it was £100+  vw is sure enough about £35.00  ... Back to front me thinks.  Will keep you updated 

[Rmachines]

Nope  Brand new n75 and no change... no faults

the engine pulls okish once it hits 3000 rpm (which is a fair bit for diesel) but its just not got that torque it should have!

The turbo spins but it sounds slow, it doesnt build up to that high pressure WOOSHSSHH ... just a distant whine ...  Any one know what my next step should be