TDI Acceleration Problems: 1.9L, 85kW (AJM)

Hello,

Today, I once again noticed that when shifting gears forcefully, there are occasional brief moments where the acceleration cuts out. However, this only happens once each time. Strangely, I consistently experience this at the same location when driving home.
Based on my feeling, I would say that the turbo cuts out for a fraction of a second, or that the accelerator pedal isn't being properly engaged. After this drive, I connected the VAG-COM diagnostic tool, but no error codes were stored.
LMM is new, and the error was already present before.

Regards,
Frank.

Hi Frank,

VAGCOM can do more than just read error codes.
Not every unintended behavior immediately results in an error.

What do the fuel injection amounts, boost pressures (target/actual), air mass flows, etc., indicate?

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

How is the AGR (agricultural land) like? Is it fenced off?

I also experienced a similar vibration at 1900 RPM in my car. Sealing the EGR valve solved the problem.

Otherwise, you should post some measurement values from VAGCOM. And since the part number is 3.8, 11...

It could be many things. Clarity is only achieved through logged values.

I experienced brief drops in performance between 2,300 and 2,700 RPM. Replacing the mass airflow sensor (MAF) resolved the issue.

Best regards, WarLord.

I experienced brief power drops between 2,300 and 2,700 RPM. A new mass airflow sensor solved the problem.

Greetings, WarLord.

'Those who can read have a clear advantage!'


...
LMM is new, and the error was already present before.

Oops, you're right about that.

Best regards, WarLord.

Hello,

Unfortunately, my VAG-COM version doesn't have an 'intelligent' interface. This causes a certain amount of lag. Because the glitches are extremely rare and only last for a very short time, you can only catch them with the VAG-COM with a lot of luck. And I haven't been that lucky so far. The glitches really only last for a fraction of a second.
I once had the pleasure of driving a Passat with the same engine, and strangely enough, it had exactly the same problem. I mentioned this to the owner, and he said that he had noticed it too, but that no workshop has been able to find the cause of the issue.
As I mentioned, the LMM is new. I haven't really paid much attention to this issue before, but it only occurred to me now while I was having it serviced that it could potentially pose a safety risk. I've been driving the car for about a year and have driven over 32,000 km. This problem has existed since day one. I can live with it, but I would feel more reassured if someone might have a tip as to what it could be.
The EGR valve hasn't changed. But maybe I should actually test it by disconnecting it.

Regards,
Frank.

Don't just disconnect it, but preferably seal it with a piece of metal.

Otherwise, I can only think of loose connections that occur in certain situations.

Hello,

Yes, I know that.

Regards,
Frank.

Hello everyone!
@frank_24: Welcome to the club!

After I finally got fed up with my clunky old AJM (presumably a piece of equipment), I decided to start doing the work that the 'Friendly' people were supposed to be doing myself.

When I replaced the fuel pressure sensor (LMM) and the diesel filter, I noticed for the first time that the pre-lift pump wasn't running... ouch. Actually, I only realized it when no fuel was coming out of the supply hose during the diesel filter replacement. That made me curious. The engine was actually running completely normally in the idle state. So, I turned that 'bleeder screw' on the diesel filter while the engine was running to see what would happen. And lo and behold, nothing. I expected a fountain or something. After a while, it started to stumble at idle, as if the engine were only running on one cylinder. So, I quickly covered the screw hole, waited a moment, and it ran again. Aha - vacuum! Why vacuum? Because the pre-lift pump isn't pumping! No entries in the error memory. Not even when I simply pull out the connector to the pre-lift pump while idling!! Great VAG system diagnosis.

Now, my still unconfirmed assumption: How many AJMs are out there experiencing jerky driving problems that might only be caused by a defective/failed VoFöPu (Vehicle Onboard Fault Finding and Prediction Unit)? Please check and post your findings! I'm going to go to VAG now and try to 'extract' the wiring diagram for the VoFöPu, because I have no voltage at the connector, and I have no idea where the relay or fuse for it is located. I'm curious to see if it will then work again!

Best regards,

Hello again!

FORGET MY LAST POST - EVERYTHING WAS WRONG!

I've already considered deleting it, but I'm leaving it in - for 'educational' purposes .

The following happened: I went to VAG in order to obtain information on wiring diagrams/part numbers. With a little persistence, I was able to get everything I needed.

Now for the kicker: After spending the entire afternoon troubleshooting the pre-lift pump (also known as the fuel pump), it turns out that my damn AJM Passat, model year 1999, doesn't actually have a pre-lift pump or a pre-lift pump relay. However, the wiring diagram and the parts catalog show something completely different. They list the pump (G6) and the relay (J17), along with the corresponding fuse (S288/slot 2. The biggest joke is that none of it exists in my car, except for the 'dummy' fuse (20A) including the wiring harness to the fuel level sensor without a pump! Tss-tss-tss.

VAG+WinELSA

That's it with my 'jerky' theorem! And I haven't made any progress at all - how great!

Hello,
Did VW 'streamline' or 'eliminate' these parts?
Best regards,
Günther

Hello!

'I have no idea! I've now read that it supposedly only happens in all-wheel drive vehicles to balance the two fuel tank halves. On the other hand, I've also read something else in the forum - I can't make heads or tails of it anymore. Then again, it might be the injectors and/or pumps. It drives me crazy when someone asks a question, people suggest solutions, and then they don't provide any feedback *UGH*! Ultimately, you get the same information from the forum as you do from the VAG workshops: blah, blah, blah...'

I need to get rid of this now, otherwise my computer will suffer. It's also incredibly annoying when people constantly point you to the search function. I've been searching for a solution to my problem for weeks, and all I keep finding are old posts (which only confuse me further) that I simply hadn't found before.

'One person writes 'my XYZ is stuttering',' another writes ''stuttering with UVW',' and a third describes their problem in yet another way. In principle, it's always the same thing, but you end up with thousands of permutations that you can painstakingly sort through to avoid being scolded by the moderators. *grrrrr* If you want to complain, please do so with educational hints (where/how/what/why). Especially WHERE! This phpBB forum is not particularly user-friendly. The forum logic leaves much to be desired! It's easy to lose track of things! Is it only me ?

Chris

PS: Please don't take this the wrong way - I just find it unpleasant! This is meant to be constructive criticism.
PSS: I'm feeling better now .

Hello,
My ARL-Bora has a pre-pump located in the tank, but it only activates when the tank is about half empty.
Therefore, it makes sense to replace the fuel filter when the tank is almost empty!
Best regards,
Günther.

AJM Chris wrote:

It's also incredibly frustrating when you're constantly being told to use the search function. I've been searching for a solution to my AJM problem for weeks, and all I keep finding are old posts (which now just confuse me) that I simply hadn't found before. Example: One person writes "my XYZ is stuttering," another writes "freezes with UVW," and a third describes their problem in yet another way. In principle, it's always the same thing, but you end up with thousands of permutations that you can painstakingly go through to avoid being scolded by the moderators. *grrrrr* If you want to complain, please do so with educational hints (where/how/what/why). Especially WHERE! This phpBB forum is not particularly user-friendly. The forum logic leaves much to be desired! You quickly lose track of things! Is it only me

You're partially right.

Our FAQ section is called "Technical Articles" (and includes troubleshooting topics). It was created with the idea of providing quick help for common problems.

Recently, for example, I expanded the "Common Causes of Errors" article to include a few PD topics after it initially only contained information about VP defects.

It is clear that PDs (presumably referring to a specific type of device or system) often cause problems, but before writing a useful technical article about frequent issues, we first need to...
-> there are many similar error symptoms present and .
-> Reports on issue resolution are available.
-> many of which, in turn, describe the same underlying cause.

Die hier / mir bisher bekannten häufigeren Ursachen für PD-Ruckeln findest Du bereits im o.g. Fach articles.

Of course, this doesn't help people with rare or different underlying causes of their problems (like you).
However, including every exotic error after a single report in a specialized article would, in my opinion, contradict the fundamental idea, because then the article would become enormous and unwieldy.

In my opinion, it should stay that way -> "Search rules" are the best.

As a helpful feature, I could imagine a kind of marker or tag for threads that not only describe a problem but also its solution.
In the simplest case, you could edit the heading and add something like "PL" to indicate "Problem Solving."

While it would involve a huge amount of reading, it would also increase the usefulness of the forum.

Should we divide the workload by creating a "Important" thread and leaving it open for a few months? In this thread, anyone (who is not a moderator) who finds a thread that hasn't been marked yet but deserves to be featured ("PL-würdig"), can post the link.
The moderators could then edit the title (e.g., add "PL" to it), and with each tag added, the search function within the forum becomes more effective because users can specifically click on threads related to "PL" to troubleshoot problems.

I don't want to be understood as claiming that the PL marking is the philosopher's stone -> if anyone knows something better, please let me know.

Hello everyone,

Yes, I also thought that I would find a solution to this problem here in the forum.
Read it. And if not, I'll get a useful answer from there.
Well, after a very long search and with the help of several clues, I also had to notice that...
that the contributions probably won't be fully completed...
You see this problem discussed in many threads (performance loss with TDI PD engines).
But the actual solution remains hidden from us to this day.

What have I gotten myself into? Even the master at VW said, 'Now it's going to cost money!'
I'm having the following problem (so I don't have to open a new thread):
It started with a noticeable loss of power from idle up to approximately 1800 RPM.
This has progressed to the point where performance in this area is almost completely absent.
I'm almost afraid to get back on the highway.
I haven't noticed any side effects: no jerking, no black smoke, and no increased [something - the original German is incomplete here].
Fuel consumption: none. No hissing sounds. Engine compartment is completely dry!
Oil and coolant levels are good, air and fuel filters are new, oil change completed.
New oil filter installed, strainer in the tank cleaned, hoses checked.
After checking everything, a vacuum leak is unlikely.
Diagnosis indicates 'middle finger' error (no useful error messages).
I passed the AU exam two weeks ago.
What does that mean? Should I sell my car? Does anyone know the magic solution?
Which sensor or component should be tested or replaced?
Help!!

Best regards, Stefan.