Tdi 140 No boost.

[mathcalv]

I have had this issue for a few weeks now where in there higher rev range in any gear the car will flat spot and get coil light flashing. Not ECU or DPF.
Vw finally got it in after 4 weeks of waiting for an appointment and come back as underboost, but were unwilling to sqeeze me in a spot even knowing I have had boost issues for past month or so.
I have replaced MAP intake pressure sensor, Exhaust Pressure Sensor with no luck.
Today I checked my actuator and N75 there was no vacuum on the actuator side so checked the hose going in to N75 and behold suction there this proved that N75 valve was indeed broken.
We put that vacuum pipe on the the actuator and slightly reved the engine and for first time in weeks the turbo spooled straight up with actuator moving as it should.
Replaced the N75 and had vacuum as should on the actuator side sure it is now fixed we started it up went of a test drive after a couple of minutes of driving it came apparent that the turbo again is not spooling even tho we know the N75 and actuator are both working fine.
At abit of a loose end in trying to figure out what else it could be....... we checked the MAF by disconnecting the plug and driving around for a couple of minutes again, the car didnt feel any worse or lumpy and performance wise the car felt exactly the same with the MAF connected or disconnected.
Did throw a code for the Boost Position sensor on actuator but after having the car throwing codes for Exhaust boost sensor, MAP intake sensors just seemed like it could be wild chase in the dark.
VW did say it could be the exhuast temp sensor but not they are not certain either.
The car will rev throughout the whole range up to redline if only pressing lightly on the throttle, but as soon as you plant your foot asking for max power it drops out between 3200-3800 like clock work every day, every gear, cant even hear the turbo spooling up at all, P.S. I have checked all the boost pipes and vacuum pipes as far as the eye can from above and below and they all look fine.

If anyone out there has any idea what this could be it would be greatly appreciated.
I know it does sound like the MAF could be dead as the car performs the same connected or disconnected, but we dont know if it is somthing else causing this lack of power and no spooling 24/7.

[Jakeee96]

Hello mate im having the same problems with my 2009 140 TDI any chance you managed to find out what was wrong in the end?

[lewisheywood]

Post is over 5 years old mate, but you never know, he might still be on the forum.

Sent from my SM-G955F using Tapatalk

[Cuprabob]

Checking the stats the OP last visited the forum in April 2013.

[Roy_01]

Create vacuüm on the actuator and check if it maintains it.
When it doesn't the actuator is broken.
When it does check the voltage in open and close position to see if the stroke is right.
The guidevanes could also be sticking.

Best thing to do is make a log with vcds while driving.

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