Kniffelaufgabe: Ursachen für unrunden PD-BUK-Kaltstart? | Posts 64+

Okay, thank you!

goettmann wrote:

Okay, let's switch gears and talk about something for the sewing box now: In some tests conducted in cold climates, we also encountered vehicles that exhibited a peculiar and stubborn starting behavior (both gasoline and diesel engines). However, the initial analyses led to a dead end. It wasn't until someone damaged the oil pan on one of these vehicles that the problem was eventually identified. After the repair, the issue disappeared. What does the oil pan have to do with this? Okay, so we figured out that a different type of oil was used during the repair compared to what our local workshop uses. So, as a test, we changed the oil in another vehicle and sure enough – the problem disappeared. Bitte gib mir den deutschen Text, den du übersetzt haben möchtest. Elsewhere, I've already told you something about the engine oil you were using.

Now that the BUK now has the correct 507.00 in the reservoir, the cold starts sound and feel practically unchanged compared to the 505.01.
Okay, when first starting up with version 507.00, one could argue that there might still be remnants of the incorrect oil in the hydraulics, etc.
However, after the next two cold starts (following approximately 20 km of driving each time), the new oil should have circulated throughout the engine -> yet there was still no noticeable difference compared to before.

The warm-up log data is no longer deviating as much from the norm on average, but this was already noticeable for about a week before the oil change, since I readjusted the pre-injection timing (from UT 180° back to approximately 130-160°, which was the factory setting).

excavate

Hi Ulf!

Has a solution to your problem been found yet?

"I'm experiencing a similar problem with my T5, where there are combustion interruptions within about 2-5 seconds after a 'cold' start. The issue seems to worsen as the starting temperature approaches the glow plug activation threshold of 5°C. Currently, I'm already having problems when the temperature is below 18°C."

Now, Steffen, GTI, and I are trying to figure out the reason why I uploaded a log from MWB 13/18/23 related to cold starting to the upload section.

Ulf, have you ever taken a log from a cold start? If not, could you please do so? I'm talking about a log that starts before the engine is started and continues for about 1 minute after it has started, while idling.
I am particularly interested in the states of your PDEs during the startup phase, after reaching the operating speed.

Best regards from Munich!

Here are the requested logs from the Passat AJM. One log was taken during a cold start this morning. The temperature reading from sensor G62 is 16.2 degrees Celsius. The other log was taken when the engine was at operating temperature. The vehicle runs and starts without problems. The rumbling noise during starting only occurs in very cold temperatures, and only if the engine has not been preheated beforehand (below -15 degrees Celsius). The injectors are PDE type, model P1.3/80/465S38, and have 55,000 km on them.
/viewtopic.php?t=23962

Great!
And thank you very much again, Steffen, for all your efforts!

Okay, now I too am part of the "Ulf's Syndrome" with my AXC .
I don't mean that it automatically sheds various "unnecessary" components, but rather that the idle speed control system on cylinder 1, which now runs at the regulated limit after starting, is malfunctioning.

Here's the log from today's cold start, where the phenomenon was particularly pronounced:
/viewtopic.php?t=23963

Also, this time again, it is noticeable that the PDE status of "32" does not appear. In Steffen's log, the motor has a value of "2" here, while mine has "128". What would be the correct value in this case?

Has anyone else ever logged the voltage of a permanent magnet (PM) motor at MWB 13, 18, or 23 before and during starting in a cold state?

Best regards from Munich!

Hello,
Maybe this will help. /viewtopic.php?t=20182
Could also log again.
haithamina

Hello Haiti!

Thanks for the link to your log!
How long had the engine been running when you started the recording?
The idle speed control has been active since the beginning of the log.
Sehe da ziemlich lange die "6" beim PDE Status, vor allem bei Zyl. 4 bis zu 50 sec. Is this normal?

Best regards from Munich!

Here's a log from the Sharan: coolant temperature is 54.8 degrees. This car exhibits the same issues as your van, but only starts showing them around plus 5 degrees Celsius. The injector pump units and complete cylinder head have 38,000 km on them and are new parts, not replacements.
Cold log likely on Sunday morning. PDE numbers are PDE-P1.1/80/520S216.
/viewtopic.php?t=23967

Thank you again, Steffen!

It really seems like everyone else has a PDE status of "2", except for me with "128".
The value "128" logically indicates a plausible engine shutdown state. While I have never seen the status "2" in my logs, I attributed it to the insufficient sampling rate at the moment of startup.
On the other hand, in your and Haiti's logs, the status "0" is still not reached for up to 50 seconds (?!?) after startup. In my case, it reaches "0" after about 2 seconds, but then the LLRR (likely referring to a specific system or process) goes completely haywire. This would mean that in my case, the control loop of the LLRR locks in much earlier than in your systems.
I'm currently not really understanding how the starting process is supposed to work correctly... Either I have a different MotorStG software that, for example, doesn't recognize "2" as a PDE status, or there might be an error on all 4 cylinders in my case, which only occurs during cold starts within the first approximately 5 seconds.

Okay, let's wait for GTI's logs, and on Sunday, I'll get yours (again, THANK YOU for your efforts, Steffen!!). Maybe Ulf will also have something to add when he returns.

Best regards from Munich!

Hello,
Please provide more context for the values "=", 6, 128, etc. I need more information to understand what you're referring to and provide an accurate translation.
/viewtopic.php?t=16802
haithamina

Hello Haiti!

I am already familiar with the breakdown of the GDP status.
Only why do some people have the "6" (=2+4) BEFORE the start, and I have the "128"?

Thank you again for the link!

Best regards from Munich!

Given the differences in the MWB 18 and 23 between the various models, it probably makes more sense to compare data from a similar vehicle with the same configuration of components. Today, I found an AXC T5 among our delivery vehicles; it was already installed.
Attached is your log file.
/viewtopic.php?t=23972
"The coolant is still at 48 degrees. And you can see that, just like yours, it shows 128 when stationary, and the 16 appears after starting, exactly as you described. Also, the BIP (Battery Indicator Program) is running in the negative for this one too. There were no error codes stored in its MSG (Main System Gateway)."
So, you can consider the history aspect covered with the pre-load pressure measurement. Apparently, this guy is supposed to be very fast.
Specifically, this one was also running noticeably disharmonically throughout the log, as if a cylinder were occasionally misfiring. The BIP PD 3 reading also deviates from the norm in this case.
The driver also confirmed that the engine runs unevenly after cold starts, even in the current weather conditions.
Unfortunately, I never get to drive the dump truck myself. It belongs to a subcontractor who works for us.

DieselBär30x wrote:

Well, let's wait for GTI's logs...

There they are:

Okay, I'm ready. Please provide the German text you want me to translate into English. I will only give you the translation.

Hey guys!

Once again, thank you very much for your efforts!!

Steffen's AXC log is very interesting. In fact, the PDE states seem to be displayed or evaluated differently here compared to the other PD-TDIs. (This seems like a great find for Ulf? )
"The status code "16" seems to persist for a very long time, for some reason. In my case, it disappears within 3 seconds, but the knock sensor from cylinder 1 is hitting its maximum limit. Regarding the correction values for the fuel injection system, they are not as negative as mine, so I will go ahead and perform the fuel pressure test that you suggested."
What also surprises me is that your AXC has a different engine control module (ECM), different coding, and a different software version, even though I had it "updated" at Volkswagen about a year ago.

The rough idle I'm experiencing only happens briefly right after starting the engine. Otherwise, it runs great visually and audibly. However, I had exactly the problem you described with the dual-mass flywheel (DMF), where I spent a long time looking for the cause of the distinct "misfires" in all sorts of other places, until the DMF finally failed. I replaced it with a new one, and it ran perfectly from the start, as if nothing had ever been wrong.
Just a tip on the side: If the AXC contacts you regarding a complaint about rattling noises during acceleration at lower RPM ranges (soon),

Once again, a huge THANK YOU for the information and effort!

Best regards from Munich!

DieselBär30x wrote:

*excavate* Hi Ulf! Has a solution to your problem been found yet?

No, but I may have found a clue in the software that is temporarily causing the idle speed to fluctuate.
I need to create some more logs first, but that will take some time (I just got back from vacation).