Passat 3C has difficulty starting in cold weather

Hello everyone,
I'm new here, so let me briefly introduce the vehicle: Passat 3C (B6), model year 2007, 125 kW / 170 PS, engine code BMR.

The following problem has been bothering me since last winter:
When the outside temperature drops below around 5°C, I have to hold down the start button for a very long time, the engine sputters excessively, and it still doesn't start. After a total of 2-3 attempts to start it, I eventually get the device to turn on.

I've been waiting for the preheating light in the instrument cluster to go out for a long time, but even waiting longer before starting doesn't change this starting behavior. Even attempting to start the vehicle multiple times by repeatedly turning the ignition on and off does not change this behavior.
I have observed for weeks and months that this behavior only starts when the outside temperature is below approximately 10°C (although between 5-10°C, it still starts and runs for a longer period with the initial attempt). However, below 5°C, the problem becomes as extreme as described above.
Along with the low outside temperatures, the vehicle needs to have been standing for approximately 7-8 hours (overnight). If I start the vehicle even briefly, I might have to turn it off immediately, but on the next attempt, it starts up within a second. Even if the standing time is less than 7 hours, the car strangely always starts immediately and on the first try. The same applies if I had previously activated the auxiliary heater; in that case, it also starts up within one second on the first attempt!
VW has already replaced the following parts in the workshop:
- new starter battery
- All 4 injector nozzles (at my expense, and using high-quality parts) -> didn't fix the starting problem, but now it runs at full speed again.

Now, they seem completely clueless and are just groping around in the dark. I also don't want them to just exchange things based on suspicion (like they implied before). Especially since, even without a guarantee, this would cost me a significant amount of money, and the PD components were already very expensive.

There are no error codes stored (currently, there's only an issue with the control unit of the auxiliary heater).
Could it be that a temperature sensor is defective? The workshop just said that something like that would be stored in the error memory.
I bought VCDS for myself a few months ago, and it's actually completely empty.
I would be very happy to receive any suggestions, ideas, or to connect with like-minded individuals, and I hope this will lead to a solution to the problem.

Thank you very much.

P.S.: I haven't found anything similar to my vehicle using the search function here on the forum, or I might have used the wrong search terms.

If you have VCDS, you can already check if the coolant temperature sensor G62 is reading plausible values.
Not every defective G62 unit will generate an error code.

The second test would be to check if the glow plugs are still working properly.
You can relatively easily check the power consumption of the candles. Simply connect the multimeter in between and compare the values. If one deviates significantly, you have a faulty spark plug.

Quote:

The same applies if I had previously activated the auxiliary heater; in that case, it also starts within one second on the first attempt!

That would actually eliminate the possibility of air being trapped in the system.

Quote:

If you have VCDS, you can already check the coolant temperature sensor G62 to see if it's reading plausible values. Not every defective G62 unit will generate an error code entry.

A plausible option when considering starting and auxiliary heating.

Quote:

The second test would be to check if the glow plugs are still working properly.

Based on my experience with these engines so far, a fault code is typically triggered when a spark plug fails.

What's left?

- Starting speed is too low when the system has not been preheated.
- not enough compression (though I doubt that's the issue).

Wow, this is happening quickly .

Regarding air in the system: As an additional description of the problem, I would like to add that it makes no difference whether the vehicle is parked on a completely level surface or on an uphill/downhill slope (I have already tested both). The problem occurs at corresponding outside temperatures, both on level ground and on uphill/downhill slopes. It also makes no difference whether the vehicle is parked with a full tank or almost empty, just before the reserve. In the workshop, they mentioned that they could at least rule out the fuel pump in the tank (which, apparently, is also a common problem with my vehicle model).
As I mentioned, for example, we had a spring day with a temperature of 17°C outside, and in that case, the lathe starts up almost immediately (with the same set time) after just a little over a second. If the temperature drops below 10°C, problems begin. According to the MFA (presumably a specific organization or standard), starting the vehicle becomes difficult, requiring multiple attempts, when the temperature reaches around 5°C.

I couldn't find a single fault with the glow plug system or the glow plugs, and neither could the workshop. I'd be happy to review it (or have it reviewed again).

'Shouldn't I also experience other problems with 'too little compression,' such as a lack of power, for example?'

'Idle speed too low when the system is not preheated.' As mentioned, if the car finally starts after 2-3 attempts of prolonged cranking, I can immediately turn it off. Then, when I restart it, it starts within a second (does that already make such a difference?). The starter motor has been replaced before; at that time, I was having starting problems whenever the engine was warm.

I hope these are perhaps important additions to better describe the error.

Can I exclude the following from your FAQ, or could this error also be temperature-dependent?
Symptoms: The PD motor only starts after several attempts, but then runs completely normally.
Common causes: Faulty or incorrectly installed Northwest position sensor (Hall sensor), or wiring issues.
Tests: Hall sensors, cables, and connectors.
Troubleshooting: depending on the defect

Okay, I'll start by checking the G62 with VCDS - if I can find it (I still need to delve a little deeper into that) .

Thank you in advance!

P.S.: Here's my complete scan using VCDS:

Complete scan:
VCDS Version: DRV 10.6.4
Data as of: 20110418.

Sunday, December 18, 2011, 4:59:40 PM: 21274

Vehicle type: 3C0
Scan: 01 02 03 08 09 15 16 17 18 19 25 42 44 46 52 53 55 56 62 69
72 77

Vehicle Identification Number: WVWZZZ3CZ7E0XXXXX Mileage: 185,190 km

00-Steering angle sensor -- Status: OK 0000
01-Motor electronics -- Status: OK 0000
02-Gearbox -- Status: OK 0000
03-Brake electronics -- Status: OK 0000
08-Climate/Heating Unit -- Status: OK 0000
09-Central Electrical System -- Status: OK 0000
15-Airbag -- Status: OK 0000
16-Wheel steering electronics -- Status: OK 0000
17-Terminal block insert -- Status: OK 0000
18-way heater -- Status: Error 0010.
19-Diagnosis interface -- Status: OK 0000.
Immobilizer -- Status: OK 0000
42-door electric. Driver -- Status: OK 0000
44-Steering Assist -- Status: OK 0000
46-Comfort System -- Status: OK 0000
52-door electric. Front passenger seat. -- Status: OK 0000.
53-Parking brake -- Status: OK 0000
55-Beam angle adjustment. -- Status: OK 0000.
56-Radio -- Status: OK 0000
62- Door, electric, left and right -- Status: OK 0000.
69 followers -- Status: OK 0000
72-Door, electric, high, right side -- Status: OK 0000.
77-Phone -- Status: OK 0000

'Der schnelle braune Fuchs springt über den faulen Hund.'
Address 01: Engine Control Module
Label file: DRV\03G-906-018-BMN.lbl
Part number SW: 03G 906 018 EM, HW: 03G 906 018 EM.
Part: R4 2.0l PPD1.2 G 4369
Revision: --H22--- Serial Number: VWZCZ000000000
Encoding: 0000078
Operating number: WSC 32247 134 83818
VCID: 74C88B886E2B

No error codes found.
Readiness: Not Available.

'Der schnelle braune Fuchs springt über den faulen Hund.'
Address 02: Transmission Label file: DRV\02E-300-0xx.lbl
Part number SW: 02E 300 043 E, HW: 02E 927 770 AE.
Part: GSG DSG 070 1156
Revision: 04507000 Serial Number: 00000606060895
Encoding: 0000020
Operating number: WSC 44551 111 44551
VCID: 160C91005817

No error codes found.

'Der schnelle braune Fuchs springt über den faulen Hund.'
Address 18: Auxiliary heater
Label file: DRV\1K0-815-007.lbl
Part number: 1K0 815 007 BC
Part number: STAN4303
Revision: 00YYY000 Serial Number: 09011075000000
Encoding: 0001011
Operating number: WSC 32522 133 81168
VCID: 66ECE1C028F7

Sure, here is the translation of the text from German to English:

'1 error found:'
00003 - Control unit.
014 - defective
Environmental conditions:
Error status: 01101110
Error priority: 2
Error frequency: 1
Lost Count: 131
Mileage: 182,378 km
Time: 0
Date: 2011.11.24
Time: 05:49:52

'Der schnelle braune Fuchs springt über den faulen Hund.'
Address 42: Door electronics. Driver Label file: DRV\1K0-959-701-MIN3.lbl
Part number SW: 1K0 959 701 P, HW: 1K0 959 793 L.
Part: J386 DOOR-SG FT 1123
Revision: 12006001 Serial number: 00000527968628
Encoding: 0000245
Operating number: WSC 05311 000 00000
VCID: 3B5A60B403F5

No error codes found.

voodoo wrote:

If you have VCDS, you can already check the coolant temperature sensor G62 to see if it's reading plausible values. Not every defective G62 will create an error code entry.

Is the BMR still one of the traditional dual sensors?
For example, in the Polo 9N platform, the instrument cluster (KI) receives the water temperature data via CAN bus from the main control unit (MSG), and the water temperature sensor is now just a simple 2-pin device...

I would now check all temperature sensors here to ensure they are reporting plausible values based on the current weather conditions and the duration they have been installed (MWB 7?).

Please log the engine speed and fuel injection/delivery rates. At startup.

"On mine, you can clearly see that it only starts boosting after a certain RPM."
These are the famous 1-2 rotations that take longer than our 1.9 mPD.

Okay, I'm ready. Please provide the German text you want me to translate.

m;


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How do you manage to log data into a chart so neatly?

Do you perhaps have a link to a how-to guide for me?

Thank you.

MWB 001 includes the electrical power, feed rate, and speed settings.

Okay, ignition on, module control unit 001, activate turbo switch in VCDS, start logging, start engine... analyze the data.

m;

Okay, so I just went outside again and tried to capture some measurements. The car had to sit and cool down for a while.
Okay, so I've read the coolant temperature from both the engine control unit and the instrument cluster.
- MSTG: G62 2°C
- Control panel setting: 1°C
At that very moment, the MFA displayed an outside temperature reading of 0.0°C. For me, these values are now within the normal measurement tolerances and are by no means 'implausible.'

Okay, so, now about the log – I'm having a problem with that. When I press the TURBO button, I always get an error message indicating that my interface isn't enabled for that function, or something like that. It seems my interface doesn't support this high-speed mode, but I'm not entirely sure about that right now. I then tried to record something using the standard protocol... I need to see if I can somehow incorporate this into a diagram like you did.
I'll post this online later.

EDIT: Since I can't manage to create the diagram myself, here are the raw data: Oh, and this was the second attempt, and the engine didn't start, so it didn't turn over:

Time Engine speed (G28)) Fuel injection quantity Pumping duration Coolant temperature (G62)
14.99 0 0 0 2
15.13 0 0 0 2
15.27 0 0 0 2
15.42 0 0 0 2
15.56 0 0 0 2
15.7 0 0 0 2
15.85 99 0 0 2
16 144 0 0 2
16.14 165 33.1 10.1 2
16.28 155 33.1 10.1 2
16.42 193 33.1 10.1 2
16.58 168 33.1 10.1 2
16.72 183 33.1 10.1 2
16.86 251 33.1 10.3 2
17 264 33.1 10.4 2
17.16 302 33.1 10.6 2
17.32 324 33.1 10.6 2
17.46 178 33.1 10.6 2
17.6 0 33.1 10.6 2
17.75 0 33.1 10.6 2
17.91 0 33.1 10.6 2
18.05 0 33.1 10.6 2
18.19 0 33.1 10.6 2
18.35 0 33.1 10.6 2
18.49 0 33.1 10.6 2
18.63 0 33.1 10.6 2
18.77 0 33.1 10.6 2
18.93 0 33.1 10.6 2
19.07 0 33.1 10.6 2

Hello,

I've shortened your log to focus on the essentials.

Perhaps your car would start more easily if the starter motor is engaged for longer than 1 second?

Best regards, Rainer.

I once made a video where I started the engine last night after it had been idle for about 3-4 hours. I hope the attachment works...
I probably have to repeat what I said about the log; it doesn't seem to be very informative, but hopefully I'll get it right this time .
Okay, even in the video, after only 3-4 hours of idling in good conditions with an outside temperature of 0°C, the car should start more easily. The whole car is shaking, and you can hear a very loud knocking sound. Before that, I had already turned the ignition on to pre-glow, then turned it off and tried to start it. But take a look for yourselves, and then I'll gradually create more videos and logs to illustrate my problem.

Hello,

It sounds relatively normal to me. The low idle speed, which already gave me a strange feeling based on the log data, seems to be confirmed in the video.

I would say the engine is perfectly fine; it's just that the starter motor and/or the battery are a bit weak.
If the "problem" being described in the video is the way the engine starts, then I don't see a need for any action.

If the "knocking" sound during cold starts bothers you, you can try using fuel additives like Ultimate, or other common fuel additives (but make sure they are suitable for use with a DPF).

Here's something you can do with minimal effort: Have your battery tested. You could try swapping the battery with one from another vehicle and then logging both the starting process (crankshaft speed) using VCDS.
Then you can determine if the starting speed is too low, and whether the battery or starter motor is weak.

Best regards, Rainer.

Well, as mentioned above, it actually takes about 7-8 hours of uptime for the really bad version, the one with multiple startup attempts.
As soon as I manage to leave the car parked for a sufficient amount of time and create a log, I will also try to record the starting process on video.
So, the battery was replaced in July, and in October, I had it checked by the ADAC's mobile inspection service, and they said it was in excellent condition. Perhaps the starter motor is already broken again.

Here are some arguments that support the theory that the problem is related to the power supply:

- Turning off the tachometer illumination upon startup.
- High RPM after starting (or is it always around 1000 RPM at 0 degrees Celsius)?
At least, it turns on when there is a power shortage .

You might also want to measure the voltage drops during startup.

m;

Okay, I just created another log and a video. Unfortunately, the outside temperature was 2.5°C according to the MFA this time, so the baseline values aren't identical. However, the car was parked for a good 8 hours. Oh, and this time the vehicle was parked straight. Even though it started very well a little while ago, here are the logged values (maybe something is still discernible), and I've added a few more values – although they are all still in their raw form.

Tuesday, December 20, 2011, 21:29:07:21274, VCDS Version: DRV 10.6.4, Data version: 20110418
03G 906 018 EM, R4 2.0l PPD 1.2 G, 4369.

Block A: ,'001,,,,Block B:,'012,,,,Block C:, Not running.
'Engine speed, fuel injection amount, pump duration, coolant, glow plug status, preheating time, supply, coolant,...'
,Time,,(Set Point),temperature (G62),Time,,,voltage,temperature (G62),Time,,,,
Marking, BRAND, /min, mg/H, °KW, °C, BRAND, , s, V, °C, BRAND, , , ,
,0.09,0,0.0,0.0,6.0,0.24,01010000,2.00,11.745,6.0,,,,,
,0.38,0,0.0,0.0,6.0,0.52,01010000,2.00,11.745,6.0,,,,,
,0.66,0,0.0,0.0,6.0,0.82,01010000,2.00,11.745,6.0,,,,,
,0.96,0,0.0,0.0,6.0,1.10,01010000,2.00,11.745,6.0,,,,,
1.24,0,0.0,0.0,6.0,1.40,01010000,2.00,11.745,6.0,,,,,
1.54,0,0.0,0.0,6.0,1.68,01010000,2.00,11.745,6.0,,,,,
1.82,0,0.0,0.0,6.0,1.98,01010000,2.00,11.745,6.0,,,,,
2.12,0,0.0,0.0,6.0,2.25,01010000,2.00,11.635,6.0,,,,,
2.40,106,0.0,0.0,6.0,2.55,01010000,2.00,9.487,6.0,,,,,
2.69, 207, 30.2, 9.3, 6.0, 2.84, 01010000, 2.00, 10.050, 6.0, , , , , ,
2.98, 216, 30.2, 9.3, 6.0, 3.13, 01110000, 2.00, 9.711, 6.0, , , , , ,
3.28, 367, 30.2, 9.7, 6.0, 3.41, 01110000, 2.00, 10.388, 6.0, , , , , ,
3.55, 832, 24.7, 8.3, 6.0, 3.72, 10110000, 2.00, 11.180, 6.0, , , , , ,
3.87, 1023, 12.3, 5.5, 6.0, 4.00, 10110000, 2.00, 11.180, 6.0, , , , , ,
4.15, 937, 16.8, 6.7, 6.0, 4.31, 10110000, 2.00, 11.295, 6.0, , , , , ,
4.45, 979, 12.2, 5.3, 6.0, 4.58, 10110000, 2.00, 11.295, 6.0, , , , , ,
4.73, 967, 12.1, 5.8, 6.0, 4.88, 10110000, 2.00, 11.520, 6.0, , , , , ,
5.03, 971, 11.5, 5.4, 6.0, 5.17, 10110000, 2.00, 11.970, 6.0, , , , , ,
5.30, 941, 13.2, 5.6, 6.0, 5.45, 10110000, 2.00, 12.875, 6.0, , , , , ,
5.60, 929, 14.6, 6.4, 6.0, 5.75, 10110000, 2.00, 13.778, 6.0, , , , , ,
5.88, 931, 14.8, 6.1, 6.0, 6.05, 10110000, 2.00, 14.003, 6.0, , , , , , ,
6.19, 946, 13.6, 5.9, 6.0, 6.33, 10110000, 2.00, 14.118, 6.0, , , , , ,
6.47, 949, 13.3, 6.0, 6.0, 6.63, 10110000, 2.00, 14.003, 6.0, , , , , , ,
6.77, 961, 12.2, 5.6, 6.0, 6.91, 10110000, 2.00, 13.892, 6.0, , , , , ,
7.06,955,12.4,5.8,6.0,7.21,10110000,2.00,14.003,6.0,,,,,
7.35, 958, 12.1, 5.7, 6.0, 7.49, 10110000, 2.00, 14.003, 6.0, , , , , ,
7.63, 964, 11.7, 5.5, 6.0, 7.79, 10110000, 2.00, 14.00, 3, 6.0, , , , , ,
7.94, 959, 11.8, 5.6, 6.0, 8.08, 10110000, 2.00, 14.00, 3, 6.0, , , , , ,
8.23, 950, 12.1, 5.3, 6.0, 8.39, 10110000, 2.00, 14.003, 6.0, , , , , , ,
8.52, 954, 11.8, 5.6, 6.0, 8.66, 10110000, 2.00, 14.003, 6.0, , , , , ,
8.81, 968, 11.0, 5.1, 6.0, 8.96, 10110000, 2.00, 14.003, 6.0, , , , , ,
9.10, 965, 11.0, 5.1, 6.0, 9.24, 10110000, 2.00, 14.003, 6.0, , , , , , , ,
9.38, 9.59, 11.1, 5.6, 6.0, 9.54, 10110000, 2.00, 14.00, 3, 6.0, , , , , ,
9.68, 960, 11.0, 5.2, 6.0, 9.82, 10110000, 2.00, 14.003, 6.0, , , , , ,
9.96, 956, 11.1, 5.3, 6.0, 10.12, 00000000, 2.00, 14.118, 6.0, , , , , ,
10.26, 793, 25.3, 9.1, 6.0, 10.40, 00000000, 2.00, 12.537, 6.0, , , , , ,
10.54, 354, 24.6, 8.2, 6.0, 10.70, 00000000, 2.00, 12.312, 6.0, , , , , ,
10.84, 0, 24.6, 8.2, 6.0, 10.98, 00000000, 2.00, 12.312, 6.0, , , , , ,
11.12,0,24.6,8.2,6.0,11.27,00000000,2.00,12.312,6.0,,,,,
11.41,0,24.6,8.2,6.0,11.55,00000000,2.00,12.312,6.0,,,,,


To make sure something was visible in the video, I turned on the dashboard light again to illuminate the speedometer.

EDIT: Would it help if I just removed the starter motor?
What's the best way to verschandeln the contacts then? Would it be okay to simply sand them down to the bare metal with sandpaper, or would I damage any protective layers?

@dieselmartin: Shouldn't the dashboard lights in the Passat turn off when the engine starts? And what would be considered a 'normal' engine speed after the engine starts? You can already see a difference in the lighting in the two videos, but the speed seems to be the same.

Get a new battery.

The tractor is still running, but the voltage has dropped to only 12.3 volts.
Seconds later, the time was just 12.0.

I "sold" my battery in late summer, and it had significantly better performance values at that time.

m;