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I have an Audi A3 8P1 170HP with an engine code BMN.
The issue I am having is with the boost of the car which is appalling and revs fluctuation.
The car boosts but not in a consistent way. When the turbo kicks in the car will boost all the way up to 3500rpm-4000rpm max then cuts out, the engine is then capped to 3000rpm where the revs start fluctuating between 2800rpm-3200rpm. When this fluctuation happens you feel the car acelerate harshly and then decelerate harshly constantly which results in a jerky ride. When the car does boost all the way up to 4000rpm, the same harsh accelerations and decelerations are felt constantly, as at times the revs will fluctuate when accelerating. If you drive the car long enough less than a mile you eventually get the coil light flashing, where the engine will be limited to 3000rpm and will not go above it until car is restarted where the cycle repeats. At times when the engine is capped to 3000rpm alot of thin black smoke is released from the exhaust pipe

You do not have to drive the car to see revs fluctuate, when idling if I put my foot to the floor on accelerator. The revs will go all the way into the redline 5000+rpm constantly, but after a short while about 5-10 seconds, the revs gradually decrease to 3000rpm and then the revs fluctuate between 2800rpm-3200rpm occur, even though accelerator is fully depressed. Eventually the coil light will start flashing followed by thin black smoke coming out of exhaust pipe if I keep the accelerator depressed. Revs will be capped until I restart the engine where the process then repeats.
When checking for codes on VCDS the Ecu throws a code. For both situations the code is the same if I reset the codes and try revving on idling or driving the symptom repeat again.

VCDS code:
000665 - Boost Pressure Regulation
P0299 - 006 - Control Range Not Reached
Freeze Frame:
Fault Status: 11000001
Fault Priority: 5
Fault Frequency: 2
Reset counter: 40
Mileage: 123627 km
Time Indication: 0
Date: 2019.06.14
Time: 00:31:03

Freeze Frame:
RPM: 3040 /min
Torque: 296.0 Nm
Speed: 45.0 km/h
99.45 %
Voltage: 14.01 V
Specified Pressure: 2492.1 mbar
Actual Pressure: 1704.0 mbar

Based on the code I have tried the following.
I have checked for boost leaks and found none all turbo pipes are clean no holes no damages. I checked all vacuum lines to the turbo and other components which are fine no split no kinks or damages.
The next step I did was replaced the map sensor and the maf sensor from a donor car no change in symptoms but donor car still runs fine mine has not rectified.
I have put in a new n75 valve a new crankshaft sensor and a replaced the camshaft sensor from a donor car still problem persists.
I have checked all the wiring from ECU to the following sensor connectors:
The electronic turbo actuator sensor, N75 solenoid valve, Egr cooler solenoid valve ,swirl flap solenoid valve, crankshaft sensor, camshaft sensor, DPF pressure sensor, egr valve, throttle body valve (bit in front of egr valve),accelerator postiton sender 1 and 2, all of the injectors and glow plugs. All the wiring is spot on with no shorts and continuity of each wire is solid.

After trying all of this I then took the car in to Audi where they ran a diagnostic and the same code showed
P0299.turbos/super charger underboost
picture bellow is audi scan from main dealer


Audi has checked the vacuum lines and have said they are fine and have done a boost leak test
Where no leaks were detected, and have said the turbo is fine. they wanted to further investigate and spend another 6-7 hours at rate of £105ph which is too much to spend atm.

To further confirm the turbo is fine. I removed the turbo charger and took it to a turbo rebuild shop
Where they disassembled the turbo to check internal condition and they said nothing is wrong internally and all the vanes are clean with no carbon or soot build up. They also checked if the turbo is calibrated correctly and the electronic sensor and actuator are all working all which has passed and they provided a certificate for showing what flow rate it is producing.
Turbo is refitted and the problem of the is still there.

Could anyone out there please help me as I am hitting a brick wall and do not know what else to do with it. Full vcds scan is attaced and the calibration test sheet is attached

cheers in advance


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VAG Error Code: 16683/15343/15343/14914/11226/12896/7384/5171/5671/000665

EOBD II Error Code: P0299

Fault Location:
Boost Pressure Regulation - Control Range Not Reached/Low Boost

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) active.
Reduced Power Output.
Limp Mode.
Limp mode: What is it, what are the causes, and how to fix it for the Audi and VW TDI diesel turbo.

Hoses/Pipes incorrectly connected, disconnected or leaking.
Charger Pressure Control defective.
Turbocharger faulty.
Diverter Valve faulty.

Possible Solutions:
Check Hoses/Pipes to/between Components.
Check/Clean/Replace Charge Pressure Control.
Check Turbocharger.
Check Diverter Valve.

Special Notes:
If the Turbocharger is faulty due to mechanical/internal problems or the exhaust system is restricted (typically the Catalyst) this fault may be the end result.

When found in 2.0l TFSI:
Check Boost Pressure Control Valve (N249) (Turbocharger Recirculating Valve) for cracked rubber diaphragm. A new/optimized Valve is available under Part # 06H-145-710-D (or newer).
Rest of World (RoW) vehicles see: Technical Product Information (TPI) 2016331 for details.
North American Region (NAR) vehicles see: Technical Service Bulletin (TSB) 01-07-70 or 2013392 for details.
When stored in conjunction with misfire codes and/or fuel trim faults see the notes associated with the following faults regarding Positive Crankcase Ventilation (PCV) failure: Crankcase Breather Valve
When found in Audi A4/S4/RS4/Cabriolet (8K): 2.0l (CAEB):
See Technical Product Information (TPI) 2031245/6 - turbocharger excessive waste-gate play.

When found in VW Golf/Jetta (1K): 2.0l CR-TDI (CBEA/CJAA):
Verify the mechanical part of the Exhaust Valve Control Module (J883) is not seized or binding.
When found in the 1.9 L TDI-PD (BLS):
Check vacuum supply from the vacuum reservoir located in the valve cover for leaks. Using a vacuum gauge, wiggle the valve cover and hose connections to check for a leak. The following photo was submitted from a customer working on a 2010 VW Caddy (2K chassis) with this vacuum reservoir problem.

16683 / P0299 / 000665 - Boost Pressure Regulation: Control Range Not Reached

Does Your VW/Audi 2.0t TSI Have A Bad Turbo

As taken from my new Free EOBD II Error Codes software
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