Passat 3C springt bei niedriger Außentemperatur schlecht an | Posts 32+

Okay, so yesterday I connected the multimeter to the car again in the garage and re-measured the quiescent current (on my Passat). The value had not changed even after more than 5 hours and remained at approximately 0.15 A, with fluctuations up to 0.18 A.
I had all the doors and windows closed, I had locked the hood latch with a screwdriver (presumably), and the vehicle was locked.
Initially, I had a terminal voltage of 12.73 V, but after 11 hours in the garage, it had dropped to only 12.16 V (I checked it again right before going to bed). During that entire time, I actually only unlocked and locked the car once.
According to your values, my car would apparently draw three times the amount of idle current .
What's the best way to proceed now to narrow down the problem - I suppose pulling fuses is probably not the solution?
Are there any known issues with the Passat in that area?

Thank you, and have a happy New Year everyone!

alphagolf wrote:

During that entire time, I actually only unlocked and locked the car once.

You must do it exactly as Martin described. The values you usually provide don't allow for many conclusions to be drawn.

@matthiasTDI96:
Sorry, I probably didn't express myself clearly. During the quiescent current measurement, I locked the vehicle and left it untouched.
I measured the voltage at the battery terminals once before taking the quiescent current measurement and once shortly before going to bed. During that time, I only opened the car once (before the quiescent current measurement) and then locked it (for the quiescent current measurement).
So, I followed the instructions and guidelines provided by you and dieselmartin!

alphagolf wrote:

... and during that time, I only opened the car once (before the quiescent current measurement) and then locked it (for the quiescent current measurement).

And that was exactly wrong. Okay, I understand. Please provide the German text you want me to translate into English. I will only provide the translation.

- Close the hood latch.
- Car to
- Wait 2 hours.
- measure, and do nothing before that!

I'd like to chime in here, as I believe the person who asked the question is being led down the wrong path. I hope this statement doesn't offend anyone.
First: The resting battery voltage of 12.3V is excellent! Also, the resting current of 150mA doesn't surprise me in a relatively new vehicle; my Sharan (2001) does the same thing if you wait only 5 minutes after locking the car. With a 100Ah battery, it starts without any problems after a week of inactivity, even in winter.
Regarding the solution: It must be the glow plugs! I'm absolutely certain! The knocking sound after starting indicates excessive ignition delay, which is caused by the low temperature. It might also emit a slight bluish or whitish smoke shortly after starting, which confirms this. But I'm not sure how much of that smoke actually gets through in a car with a DPF, so it doesn't necessarily have to happen.
The glow plugs are internally resistance-regulated. You can certainly show another iteration, but it won't be able to handle enough power.
Just exchange them and do nothing else, that's my advice.
Good luck!

Sure, here's the translation:

"Just my two cents:"
"That's just my opinion."
"That's just my take on it."
"That's just my perspective."
"That's just my point of view."
"That's just my thought."
"That's just my idea."
"That's just my suggestion."
"That's just my advice."
"That's just my recommendation."
"That's just my opinion."
"That's just my take on it."
"That's just my perspective."
"That's just my point of view."
"That's just my thought."
"That's just my idea."
"That's just my suggestion."
"That's just my advice."
"That's just my recommendation."
"That's just my opinion."
"That's just my take on it."
"That's just my perspective."
"That's just my point of view."
"That's just my thought."
"That's just my idea."
"That's just my suggestion."
"That'
"What is the measurement accuracy of your measuring device? You always talk about "only" two decimal places and the ampere measurement range. Does this device not have a milliampere (mA) measurement range? It's possible that the measurement accuracy is simply insufficient. In cheaper devices, there can be a few percentage points (of the currently selected maximum measurement range), plus some additional digits. This can lead to an inaccuracy in the 2A measurement range that is greater than the actual measurement value." Therefore, if necessary, repeat the measurement using a (borrowed) measuring device with higher resolution. (It should at least be able to resolve down to 1mA).

2) @ Nikolabob: The glow plugs are individually monitored by the BMR (Engine Control Unit) due to Euro 4 regulations and any faults would be stored in the error memory.
Furthermore, if he only manages to start the engine after several attempts, even when the ambient temperature is between 0-5°C, then all the glow plugs must be faulty and the compression must be extremely low. A properly functioning BMR (presumably referring to a specific engine management system) should start without any problems, even with the glow plug fuse removed, at a temperature of 0°C. I therefore don't believe in your theory.

Greetings.
Guste.

Based on my understanding of the log, the starter speed is just over 200 RPM, which I believe should be sufficient both in terms of combustion chamber temperature and for enabling the fuel injection. While I'm not 100% sure about the current, low compression ratios, I still believe that it's not relevant below 0°C.
"And I believe you about the monitoring of the glow plugs, but how is it done? Is there a shunt somewhere that actually measures the current draw? I think it's more likely that a cold test is performed, meaning it's only checked for continuity. But that doesn't say anything about the resistance under load. The glow plugs have a regulating coil inside, a variable resistor, similar in function to a PTC. There could be problems there that, in my opinion, the control unit cannot detect." As I said, this is just speculation, as I don't know the circuit.
What, in my opinion, supports the theory about the glow plugs is the way the engine runs after it starts: If the problem is related to the battery, it should run normally after the initial start. This engine is misfiring significantly and vibrating, indicating a high ignition delay and, consequently, poor combustion stability (large cyclic fluctuations during that time).
I'm not familiar with the installation situation for a 4-valve head, but if they're not very difficult to access, I would replace them immediately as a precaution. After all, the much more expensive PD (possibly referring to pressure differential) components were also replaced as a precaution. A colleague recently replaced all four on a Golf with only 120,000 km, and he experienced the exact same symptoms that you're describing. They all had a draft, but none of them were glowing.

Nikolabob wrote:

First: (Quiet) A battery voltage of 12.3 V is excellent!

12.3 V corresponds to approximately 50% charge, and you call that excellent.....

Regarding the spark plugs: Does the valve cover need to be removed on the 16V engine?

Okay, I have something new to report in this case.
I dropped off the car, and they performed a quiescent current measurement over an extended period (overnight) using a motor tester.
'First, they adjusted the delay time for the Bluetooth hands-free system from 30 minutes to 0 minutes (I never even used that thing). Then, they said there was a problem with the rain sensor.' Then I told them about the umbrella lock, and they removed it again .
'Nevertheless, the values, even after the diagnosis, were still too high, averaging around 0.112 A. Now, they want to replace all four door control units, and according to the mechanic's initial estimate, this will cost more than 900 EUR for this car. Since that seems too expensive, I will probably ask another workshop for a diagnosis first.' Now, everything on my car is basically broken except for the blinking light in the door.
Are defective door control units even plausible? Does that have something to do with the window lifters?

Hi.


and it probably won't work after all...


I've already spent almost 1000€ on parts for my BMW Touran, and it still starts just as sluggishly (sorry) as it did in the beginning...


Even with a truck battery and charger, nothing changes. It needs to crank for 3 seconds, or just a little extra starter assistance, otherwise it will stall again. It doesn't happen every time, and it doesn't happen when it's really cold. If the auxiliary heater only runs for 3 minutes (just enough to reach full power), it starts 'normally' every time.

Temperature sensors are new, LMM (mass airflow sensor) is new, differential pressure sensor is new, filters and other stuff are new. U-pressure valves are working, the hoses are tight, all flaps are functioning, glow plugs and wiring harness are new... I don't even care anymore.


I'd like to test the glow plug injectors sometime when I'm cleaning things up... but I don't really have a logical explanation for why I want to do that... By the way, I can't really pinpoint any pressure loss in the head from either the diesel or coolant side, and the pressure from the tandem pump seems to be correct... I'm not sure what's going on.


What I don't understand is that after just a very short period of the heater being on, the car always starts easily, and after 3 minutes, the engine isn't much warmer than it would be otherwise, which seems like it shouldn't help that much with starting. Maybe someone should check if the engine temperature sensor has already risen a few degrees at that point.


Sincerely,


Marc.

I assume you don't have a VCDS device, and without a VCDS, the diagnostic tool is malfunctioning.

If you're talking about me, but I'm not using it right now. The thing is broken again (for the 3rd time within the warranty period...).


'But I'm wondering what I should be logging... it's spinning at just over 280 RPM when started by the starter.'