Underboost - Stuck in Limp mode

a little guidance here guys if you would be so kind.
i was on the way home from work about 7 miles driven - 4 miles go go and from stopped at a stop sign my 04 PD BEW 192Kmiles Went into limp mode.
suspected it was the pancake pipe to intercooler connection I've had a leak in prior. sealed up and verified that connection is good. have already done the dog collar fix as well.
i've been trouble shooting this for the last 2 weeks and can't find a solution. I've got 22" of vacuum at idle at the turbo. no movement in vacuum when reving in neutral from under the car.
replaced the N75 Valve. perhaps some form of improvement? maybe?
Unplugged the MAF. this seems to result in maybe a little more power.
pulled the white and black vacuum check valve p/n 046905291A
i'm able to blow air through this valve in both directions - is this the culprit or will it only check vacuum?
the following are engine codes that are current. driving with the MAF unplugged most likely resulted in the P0101 & P0102 codes.
P0101 MAF Implausable Signal
P0401
P0299
P0102 MAF Signal too low

The one way valve should only let air go one way. If you can blow through, you should'nt be able to suck back without it closing, and vise versa...
Does the actuator move? With vacuum applied does it move?


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P0401 Seems likely that the EGR is sticking open causing low boost. Definitely triple check all boost hoses for leaks. I found the small ones on the intercooler can blow and not be visible... Often have to pull them off to inspect fully

0299

https://forums.tdiclub.com/showthread.php?t=271408

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From: http://wiki.ross-tech.com/wiki/index.php/16785/P0401/001025

Possible Causes
Exhaust Gas Recirculation (EGR) Flow restricted/clogged
Exhaust Gas Recirculation (EGR) Valve stuck closed/leaking/faulty
Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve faulty
Exhaust Gas Recirculation (EGR) System faulty

EGR was blocked off after i pulled the head and replaced the cam and cleaned the intake. so no EGR problems. Or sooty intake problems.

replaced the check valve. no improvement.

pulled vacuum on the vnt actuator. it moves and cycles.

i'm at a loss for what to do next?

Do you have VCDS? Try calling the actuator with VCDS, and taking some logs to see what's happening.

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i only have VCDS Lite. is there a way to call the actuator with the lite version?

Doesn't appear to be, however, I would look through the program to see what's offered. Unfortunately, the lite version is really limited, even the registered version.


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Hatchet Ratchet said:

EGR was blocked off after i pulled the head and replaced the cam and cleaned the intake. so no EGR problems. Or sooty intake problems.

Click to expand...

Did you get a tune for the EGR block off?
From my other post:
Exhaust Gas Recirculation (EGR) Flow restricted/clogged

VCDS is free provided you have the hardware. Light is for the hacked version or something. Still it should work

wonneber said:

Did you get a tune for the EGR block off?
From my other post:
Exhaust Gas Recirculation (EGR) Flow restricted/clogged

Click to expand...

no i didn't get a tune to go with the egr block off. just made my own block off plates.

Mongler98 said:

VCDS is free provided you have the hardware. Light is for the hacked version or something. Still it should work

Click to expand...

can you direct me to the more capable version of VCDS? the lite version from ROSSTECH seems limited to reading and clearing codes and seeing what sensors are reading back but not how to do any of the disable or call for solenoids to move.

You must buy the cable to use the full version, however, the code is stored in the cable.
https://store.ross-tech.com/shop/vchv2_ent/

They can be rented at a couple vendors, and also found in the classifieds section on occasion.
http://forums.tdiclub.com/forumdisplay.php?f=16

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Mongler98 said:

VCDS is free provided you have the hardware. Light is for the hacked version or something. Still it should work

Click to expand...

The Lite version is the same as the full version with a -few- things disabled.
Biggest thing is the timing graph will not work.

You can get into all the blocks as far as I know.
I've used a few of them before I registered it, mostly to get the timing graph.

From what I understand the hacked versions all seem to have a virus in them.

https://www.ross-tech.com/vcds-lite/index.php

Limitations of VCDS-Lite compared to VCDS even if*Fully Registered:*

No Generic OBD-II*
Won't work with CAN-Bus vehicles*
Fewer fault code definitions and label files*
No built-in Activation (you'll be limited to a single PC)*
No Advanced Measuring Blocks*
No Acceleration Measurement

Refer to our*VCDS Function Chart*for more details



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