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-   -   Cold start - missing boost (https://forum.a8parts.co.uk/showthread.php?t=13279)

peiiider 1st August 2017 03:25 PM

Cold start - missing boost
 
So..

More and more often when I start driving the car from cold, I get no boost pressure.

When I reach 60-70kph I get flashing glow plug light, limp mode (even less power than before) and fault code P0235.

If I notice when I start driving that boost is missing, I can drive carefully on flat ground for 10 minutes without pressing the pedal too hard, no "limp mode" and no flashing light, just ALOT of missing power.. When the engine reaches normal temp, I can park it for 6-7 minutes to let it "shut down", then start and everything is fine.

If I start from cold, even the times it drives normal, and then stop the car before it's completely warmed up, I will have no boost when I start it again.

As long as the engine is warm, everything is fine. Always.

Tried changing boost sensor and the plug, that didn't help.

Turbo actuator maybe ?

Outtakes from a few vcds scans I did some time ago, before I understood I had to let it "shut down" to start working again:

Quote:

Monday,13,February,2017,18:19:50:63838
VCDS Version: Release 15.7.4 (x64) Running on Windows 10 x64
www.Ross-Tech.com
GK-Racing
Address 01: Engine Labels: 059-907-401-ASB.clb
Control Module Part Number: 4E0 910 401 S HW: 4E0 907 401 C
Component and/or Version: 3.0L V6TDI G000AG 0010
Software Coding: 0011973
Work Shop Code: WSC 16882 001 1048576
VCID: 2B5522208AFC6E66FB-807E
1 Fault Found:

000565 - Boost Pressure
P0235 - 001 - Regulation Range not Reached - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 192539 km
Time Indication: 0
Date: 2017.02.13
Time: 18:16:51

Freeze Frame:
RPM: 2037 /min
Torque: 339.3 Nm
Speed: 67.2 km/h
Absolute Pres.: 1846.2 mbar
Absolute Pres.: 1142.4 mbar
Mass Air / Rev.: 599.3 mg/str
Temperature: 4.5°C

----------------------------


000565 - Boost Pressure
P0235 - 001 - Regulation Range not Reached - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 192542 km
Time Indication: 0
Date: 2017.02.13
Time: 18:23:57

Freeze Frame:
RPM: 2331 /min
Torque: 358.8 Nm
Speed: 53.8 km/h
Absolute Pres.: 2233.8 mbar
Absolute Pres.: 1234.2 mbar
Mass Air / Rev.: 640.4 mg/str
Temperature: 9.0°C

------------------


000565 - Boost Pressure
P0235 - 001 - Regulation Range not Reached - MIL ON
Freeze Frame:
Fault Status: 11100001
Fault Priority: 0
Fault Frequency: 1
Reset counter: 255
Mileage: 192548 km
Time Indication: 0
Date: 2017.02.13
Time: 18:30:07

Freeze Frame:
RPM: 2268 /min
Torque: 249.6 Nm
Speed: 56.0 km/h
Absolute Pres.: 1581.0 mbar
Absolute Pres.: 1122.0 mbar
Mass Air / Rev.: 564.0 mg/str
Temperature: 4.5°C

Mechcanico Lee 9th August 2017 08:57 PM

Is vnt turbo vaccum or electric control ?

peiiider 10th August 2017 10:59 AM

Any ideas ?

Turbo has the electric vnt unit/actuator.

Mechcanico Lee 10th August 2017 04:19 PM

When you start it do you see vnt mechanism get pulled over one way , when you blip throttle do you see vnt mechanism do a little flick

Mechcanico Lee 10th August 2017 04:34 PM

In hook the actuator arm off the vnt and ensure turbo vanes move smoothly and freely

peiiider 10th August 2017 07:24 PM

The linkage moves smoothly, and the spring in the actuator pulls it back fine.

I haven't inspected what happens when i start the car, but since it works fine when everything warms up, I guess that points to something not right inside the actuator electronics..

Anyway the turbo has done 200k km, so maybe it's life is almost over..

peiiider 15th August 2017 08:11 PM

The last few days I have also gotten code P3348, so definitely something not right with the turbo actuator..

Today I connected the laptop when I drove off, and I see that "specified boost" works and "actual boost" is pretty much zero. Also, the boost regulator duty cycle is stuck at 16%..

Later when everything was fine, the duty cycle varied between 20-80%.


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