3.0 BiTdi 320ps Boost pressure regulation

[Nomakbg]

Hello friends,

since 1-2 months i have the following problem.

When accelerating sometimes in the higher gears, sometimes in the lower it pops up in to limb mode and has power and turbos cut until car is shut down and started again.

On the diagnostics it records the error :

viber_image_2022_06_20_09_52_22_739_2__c70ec548f059060f12b0628cc77e021458bd83f2.jpg


Turbo was removed and checked, no problems,
everything connected or working with the turbo was checked and no problem,
the exhaust and DPF was checked and removed, no problems.

I am starting to hit a wall here. Please for any assistance.

[dean warren]

Hi it says 4 faults found but you only show 1….
What are the other 3 faults?


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[Nomakbg]

Hi it says 4 faults found but you only show 1….
What are the other 3 faults?


Sent from my iPhone using Tapatalk

Hello,

only nox sensor bank 2, the others are not relevant to the issue.

The repair shops idea is to replace the 2 temperature sensors who are registering the exhaust gasses.

1 of them is showing +800 degrees values and 0.7 backpressure.

[VAG-Abound]

You should be able to take it for a drive and log actual / requested boost during steady driving and with moderate to high acceleration on an uphill. If there are clear, consistent deviations then something is happening in the turbo, boost pipes or sensors.

[Nomakbg]

Hello,

car was driven and tested 5 days every day, there are no problems or faulty sensors, only exhaust gas sensors. One is showing -40 and the other +800 value and the backpressure is 0.7 bar which i understand is high. Nothing else is faulty, it has been tested and disassembled with no issues found. So my question is could it be possible to be these 2 temperature sensors?

[mickeybo]

What is the engine code for your car. temp sensors can be easily be checked out either on or off the vehicle but i cannot see them being the problem

[VAG-Abound]

car was driven and tested 5 days every day, there are no problems or faulty sensors...

What sort of testing does that mean? If it didn't cause the problem to occur the it is unlikely to help you fix it.

[Nomakbg]

What is the engine code for your car. temp sensors can be easily be checked out either on or off the vehicle but i cannot see them being the problem

4G2FN is what you need? I am also bit curious about the temp sensors to be the issue, and do not want to change something is not the problem in general because those sensors are not cheap.

[Nomakbg]

What sort of testing does that mean? If it didn't cause the problem to occur the it is unlikely to help you fix it.

Mechanics were driving the car trying and replicating the problem, watching live data on all the cars components to see anything out of the usual or which may be the cause.
Turbos were tested on a machine, vacuum was tested, the servo motor for the turbos was tested,all the turbo pipes and intake was checked, the exhaust and the DPF was also checked.

All seemed good but the only faulty thing was the temp on one of the temp sensors, as mentioned the healthy one was showing values in the normal range -40 but the other was showing way higher temps.
They say that after changing both sensors they can determine if the sensors are the fault or something else.
Forgot to mention that it turns out turbos are okay but sometimes the car just cuts them off when she doesn't like something, problem is to find out what is reason.

[VAG-Abound]

If there is no consistent variation in requested vs actual boost pressure that might usually be within tolerance but just nip outside it sometimes including during sustained hard acceleration on an incline then it may be an electrical problem with those sensors. I'm not sure if the figure shown in your screenshot is a momentary actual, or averaged across time, so a brief zero from a broken wire would push down the average.

Is there somewhere that you can pretty reliably make the problem happen? Unplugging some sensors will make it use a default value, which is sub-optimal but keeps the turbo active. If you can't make it go into limp when normally would with the sensor unplugged than it may be the cause.