A6 C7 3.0 BiTDI engine shaking like crazy when cold

[ibrica]

Hello everyone, i recently got myself an A6 C7 3.0 BiTDI 2012. with 220K km on it.

The car was checked by an official dealership prior to purchase, everything went smooth, the only problem was the coolant was leaking, and i had to change some sort of a thermostat down between the heads. Here is the picture of the part that was replaced: https://prnt.sc/155h62e

Additionally here are the pictures of the process, what needed to be taken apart:

Screenshot

Captured with Lightshot

prnt.sc

Screenshot

Captured with Lightshot

prnt.sc

Couple of days ago, i started the car, i noticed the engine was shaking, waited a bit for it to settle. I started driving and all of the sudden revs started dropping down, the car almost shut down, gave it a little gas and the revs were unsteady, jumping all over the place between 1000-2000 RPM. It lasted a couple of minutes, the car warmed up and everything was gone. A day after that, i noticed the same thing when starting the car, popped the hood and felt a burning smell, in addition to that i saw a bit of white smoke coming from the the place where turbo geometry goes into the turbo, however no smoke of any kind from the exhaust pipes, here is the screenshot:

Screenshot

Captured with Lightshot

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I again drove off, when i was on the the brake, transmission in D, the car started shaking and hitting, i couldn't locate where the hits came from.

Went to the mechanic, the problem went away itself for a couple of days. I tried with another fuel from a different gas station, did the DPF regen, car was running fine for 2 days, then the same thing happened this morning. I wasn't even giving it any gas, I litterally just released the brake, the car almost shut off. As soon as the car warmed up, the problem was gone.

I did a VCDS scan after the first time i noticed the problem, this was the result:

Sunday,06,June,2021,21:37:01:00009
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 21.3.0.0 (x64)
Data version: 20210226 DS325.0
www.Ross-Tech.com


VIN: WAUZZZ4G3DN043374 License Plate:



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


Address 01: Engine Labels: Redir Fail!
Control Module Part Number: 4G0 907 589 A HW: 4G0 907 589
Component and/or Version: 3.0BTD EDC17 H23 0004
Software Coding: 0A2A4012052601020000
Work Shop Code: WSC 02391 785 00200
ASAM Dataset: EV_ECM30BTD0114G0907589A 001005 (AU57)
ROD: EV_ECM30BTD0114G0907589A.rod
VCID: 326BAFCF652F681B05-8066
2 Faults Found:

13812 - Exhaust Gas Temperature Sensor 4 Bank 1
P246F 00 [096] - Implausible Signal
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 236489 km
Date: 2000.00.00
Time: 00:00:00

Engine RPM: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 31 °C
Intake air temperature: 19 °C
Ambient air pressure: 950 mbar
Voltage terminal 30: 12.400 V
Unlearning counter according OBD: 38
Exhaust gas temperature sensor 1: 31.2 °C
Exhaust gas temperature sensor 2: 222.0 °C
Exhaust gas temperature sensor 3: 21.6 °C
Exhaust gas temperature sensor 4: 107.5 °C
Exhaust gas temperature S4-B2: 14.2 °C
Shut-off timer: last engine shut-off time: 35286 s

10382 - Thermostat for Cylinder Head
P199E 00 [032] - Open Circuit
Intermittent - Not Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 1
Mileage: 236229 km
Date: 2021.06.02
Time: 09:53:16

Engine RPM: 0.00 /min
Normed load value: 0.0 %
Vehicle speed: 0 km/h
Coolant temperature: 20 °C
Intake air temperature: 14 °C
Ambient air pressure: 940 mbar
Voltage terminal 30: 11.780 V
Unlearning counter according OBD: 36
Shut-off timer: last engine shut-off time: 45291 s
TECU t Max: 86.2 °C
Mean injection quantity: 0.00 mg/stroke
Ambient temperature: 14.8 °C
Control Module temperature: 40.0 °C


Readiness: 0 0 0 0 0


I cleared the errors, they did not come back, check it today again.

I should mention that the oil and filters were done every 12-14000 kilometers, all 6 new OEM injectors last year.

If anyone has a slightest clue or maybe had a similar problem, your help would be trully appreciated

Edit: Here are the measurement from the injectors:

Cyllinder 1: -0.04 mg/stroke
Cyllinder 2: 0.01 mg/stroke
Cyllinder 3: -0.19 mg/stroke
Cyllinder 4: -0.09 mg/stroke
Cyllinder 5: -0.04 mg/stroke
Cyllinder 6: -0.06 mg/stroke

 

[Mo-S3]

That part is a common failure on these engines. Ive changed mine as well. You need to check if all the sensors have been plugged back in properly. Has one come off? The code for thermostat on cylinder head is either disconnected or dead

 

[TheStigOnline]

That part is a common failure on these engines. Ive changed mine as well. You need to check if all the sensors have been plugged back in properly. Has one come off? The code for thermostat on cylinder head is either disconnected or dead

This and check the related fuses, as well as relays, open circuit should be the focus for the time being

Also, even if all the sensor plugs are in/on, give them a spray with electrical contact cleaner

And clear codes, ignition off, wait as usual, then back on, retest for faults

After that it's probably replacement of the faulty part(s) if it continues

(side note, those injector values appear within the expected norms)

 

[ibrica]

Update, i changed the fuel, and the thing is completely gone.. crazy.
Anyway, thanks for your help.

 

[ibrica]

Update, the problem is back, when the revs are low, the car is stuttering. I am starting to think the DPF is the problem here, i turned the car off 2 times yesterday when the regen started (had to). The first time when the problem ocurred, i canceled the regen 3 times straight before actually doing it.. any thoughts on this?

 

[ibrica]

I tried to force the DPF regen in VCDS, at first it would fail due to security reasons, and these are the errors that followed after i checked for fault codes followed with a blinking coil light on the dashboard:

Screenshot

Captured with Lightshot

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Screenshot

Captured with Lightshot

prnt.sc

After this, i went and topped up the tank since i realized that my tank is under the half, i managed to start the service regen and the measured and calculated values dropped by 50%.

The ultimate questions is, does this mean my DPF is clogged? Or is it the EGR maybe?

 

[TheStigOnline]

It means you're probably past the DIY phase and should have the condition diagnosed by a specialist who can isolate a solid root cause

 

[ibrica]

An update, maybe it can help someone in the future..

Went to the mechanic, we took off the intake, disasembled the egr and cleaned it.. problem gone, car drives a lot better.. no more shaking and stuttering.

Thanks everyone