Engine misfire at partial load after replacing EGR and MAF sensor

Hello everyone,

It's about a 2018 Audi A6 Allroad with the CVUA engine, 320 horsepower, and a bi-turbo TDI (diesel) engine.

The trigger was an emergency stop and an entry in the event log indicating that the flow rate through the EGR valve was too high.
A workshop (not an Audi dealership) then replaced the AGR valve.
Unfortunately, the error message was still present. It turned out that only the mass airflow sensor (MAF) was defective.
It was then replaced, and everything was fine.

Unfortunately, the engine has been running quite rough in the partial load range (both when warm and cold) ever since.
Since I had lost confidence in that particular workshop due to a few issues, I decided to go to an Audi dealership instead.
He discovered some connectors that weren't properly engaged and corrected them. He also found a vacuum hose that wasn't correctly attached, but he has now fixed it.
On that day, the error did not reappear.
Two days later, unfortunately, it happened again.
However, the event log is clean, and everything is working perfectly under load.

The engine was completely overhauled at 13,000 km.
So, including pistons, turbocharger, and injectors.
Only the AGR is different, but that's new anyway...

My question regarding this is as follows:
Which extended metadata fields should I log here to potentially trace the cause?

Thank you for your efforts.

Best regards,
Wool.

Hi,

Autoscan?

Was about a switch or bypass system for the turbochargers in those engines?

You first need to figure out where the jerking is coming from, because the injectors are doing strange things, they haven't been properly calibrated, or the engine control unit is reducing the fuel injection amount for some reason.

More detailed description of the stuttering and how it can be triggered?

Best regards, Rainer.

Thank you for your reply, Rainer.

The car scan is error-free.

The engine was running perfectly fine before the EGR and MAF sensor replacements, except for the issue with the limp-home mode. However, it definitely wasn't misfiring.
And those new injectors and the new turbocharger were already installed.
The injectors, like the EGR valve, were programmed/calibrated.

I checked all the connectors and hose connections again a little while ago, as far as I could reach them.
Everything is fine, even inside the connector.

I can try to reproduce the stuttering issue tomorrow (it might be difficult).
It usually happens when it's running at a low load level.
I need to go visit my mother and I'm going to try stretching with VCDS enabled.
80 km in each direction, including highways, country roads, and city streets.
If it's glitching, I'll trigger a log.
I will choose the values tomorrow based on my gut feeling.
Going there one way... Coming back another.
The log should start whenever there's a stutter or glitch, and continue for a few seconds afterward.
I would have liked to get some tips on which values would be appropriate here. I'm completely out of touch with the newer technology and my age doesn't help either...
If I manage to create some usable files, I will get back to you tomorrow around 1 PM.
Otherwise, of course, but unfortunately without the files in that case...

Let's see what happens.

If the LMM is a replica, you might search until you're blue in the face.

If such a part is installed, I would personally replace it with an OEM (Original Equipment Manufacturer) part or a part from the original manufacturer before continuing to troubleshoot.

...it wouldn't be the first time that such symptoms have appeared without any error codes being logged.

Quote:

The Autoscan is error-free.

I asked for a car scan. The word itself tells you why. Just click on it.

@Rainer

Please don't take this the wrong way, but I initially checked the scan without saving it, so that's why I wrote that it appeared to be clean.

Here's a new car scan from just now, attached as a file.

We've written about error code 0010 on the interface before. I never found a solution for it, and the adapter still works, so I didn't really care about it...


@Uncle BM

Thank you for your suggestion.
I just checked with the audio parts expert about that.
The LMM and EGR valves are definitely genuine parts.




Unfortunately, the error only occurred briefly today, and I was unable to use the laptop due to traffic conditions.
Later, I desperately tried to reproduce the error again, but unfortunately, I was unable to do so.
However, I will continue to try and create some logs if the error occurs again.

There must be a reason for it...
I really don't want the engine to break down again...