unknown limp mode

[n0.j0y]

specs:
2002 vw jetta gls model with a alh 1.9
around 235,xxx miles on motor and chassis
had to swap less ****ty transmission in.
stock motor all i’ve done is egr delete and egt and boost gauge.

my problem was the turbo wasn’t building much boost so i replaced and simplified vacuum lines and still most boost i would see is 12psi, couple weeks later i discovered the egr delete gasket has blown out the side so i patched tht up and magically i’m pushing close to 25 psi (i thought stock turbo would be 18max?) the engine was more alive and handling it very well but would trigger a limp mode when pressure went to 25psi and limit it to 15psi max and would also give a fuel cut.

my questions
is this a stock turbo?
would i need a larger map sensor to handle 25psi?
why do i still have a boost cut

 

[P2B]

Diagnosing and Fixing Limp mode for A4 1.9TDI [low power troubleshooting]

Diagnosing and Fixing Limp mode for A4 1.9TDI By Canadian Grizzly Read the entire post prior to jumping to conclusions. This is a general overview on how to diagnose and fix a A4 1.9TDI that goes into “limp” mode due to an overboost of the turbo. While I’m by no means an expert I’ve gleaned...

forums.tdiclub.com

 

[n0.j0y]

maf sensor isn’t the issue the vacuum lines aren’t the issue and the n75 seems fine ,the only thing i haven’t checked is the turbo actuator and thats where i’m thinking the issue lies.
Before i dive into tearing into the turbo i was wondering if anyone had any suggestions, before i cleared the over boost code and the problem seemed to be gone i could floor it without it going into limp mode and it would push over 18psi easily,
now it won’t even build boost past 3500rpm and will only hold steady boost on the highway max i’ve seen is 10 but it takes forever and goes into limp mode as soon as it goes over, i’ve checked codes and i’m not getting a single code tht has to do with boost.

all vacuum lines are correct there are no air leaks to my knowledge the intercooler piping is connected everything kinda points to the turbos internals giving out am i right?

Any advice or information helps thanks.

 

[P2B]

it won’t even build boost past 3500rpm and will only hold steady boost on the highway max i’ve seen is 10 but it takes forever and goes into limp mode as soon as it goes over, i’ve checked codes and i’m not getting a single code tht has to do with boost.

Something does not add up, the ECU always sets a DTC when it triggers limp mode.

What leads you to suspect limp mode? What DTCs are set? How did you determine the MAF is good?

 

[n0.j0y]

currently the turbo will only boost to 2 psi from 1000rmp till 3500rmp and only on the highway is when the turbo tries to boost over 10 and shortly after you can feel and see it trigger a limp mode either a boost cut or a fuel cut.

i’ve scanned all the vacuum lines made sure no air was leaking as for the maf sensor i unplugged it and did a loop around my block and it blew a pretty big cloud of unburnt diesel(white smoke) so either the maf is working or something else was put to the spot light.

as for the codes p0234 overboost code
code p0128 temperature below control range
code p1556 charge pressure control
code p3105 valve for intake manifold flap
and a egr code p1441

looking back at the photos i see a maf code p0102 singla too low (i’m wondering if this is an indication tht is bad:0)

 

[P2B]

i’ve checked codes and i’m not getting a single code tht has to do with boost.

as for the codes p0234 overboost code
code p0128 temperature below control range
code p1556 charge pressure control
code p3105 valve for intake manifold flap
and a egr code p1441

looking back at the photos i see a maf code p0102 singla too low (i’m wondering if this is an indication tht is bad:0)

So you actually have two codes related to boost.

Start with the limp mode diagnostic thread I linked above, in particular run the N75 output test of the boost control system.

 

[Kramer]

get a mighty-vac on the actuator and see if the arm travels smoothly.

This sounds like my bew before i put a dog collar on the intake connection to the ASV.

 

[n0.j0y]

hello here is the update so far i’ve tried doing some research on using vcds to move the actuator only issue is most of them used a mighty vac or something similar i hear the suggestion but unfortunately i don’t have that so i tried seeing if i could move the lever manual and it moved but slightly however on vcds in charge pressure control at idle everything seems lil off after 1300rmp it all turns red charge pressure from n75 stays available but on bust actual it’s stops showing mbar, boost specified group 011 instead of OFF and also engine speed from g28 turns into an error.

i don’t really know what any of this means is this the wrong place to look for what i’m looking for?, does it only read for idle to 1300+?, would this be an actuator problem or a n75 solenoid promblem?.

i’m was planing on replace the whole turbo with a slight upgrade and what better time then wen a actuator goes bad but if it’s the n75 solenoid i could get it off a parts car quick so any thoughts on this would help.

 

[P2B]

hello here is the update so far i’ve tried doing some research on using vcds to move the actuator only issue is most of them used a mighty vac or something similar

The only research needed is to watch the video I linked above which shows you how to use VCDS to test the boost control system - a few clicks of the mouse is all it takes.