Ruck beim Beschleunigen, BLS mit DPF | Posts 48+

The turbocharger pressure sensor can be completely ruled out as the cause.

Assuming the intake manifold is cracked, would it be possible to detect this by smelling exhaust fumes? I'm asking because I wonder if exhaust gases could enter the intake system through the EGR valve when idling or at low speeds, or am I mistaken?

Second theory: Could it be a problem with the control unit?

What else can I do now...? Should I spend another 80€ to have the control unit checked, or should I completely disassemble the car again and remove/inspect the intake manifold as well (I already have a used one on hand), and also have the turbocharger inspected?

Third theory: Could it be that the cylinder head is cracked in such a way that no coolant leakage is audible?

Fourth theory: Feed the car with medication and hope...

PS: Or could it be the pump injectors? After all, the engine runs very unevenly at full throttle when idling, which I haven't experienced with any other diesel engines before. Is this normal for TDI engines?

In the Seat Leon forum, a user named Icefox reported very similar problems, except that he was generally experiencing too little boost pressure. After replacing the PDE (presumably a pressure control element), the issue was temporarily resolved.
But if my engine runs smoothly at idle, it shouldn't "actually" be the PDE, right?

"Sometimes, when the engine is cold and I accelerate fully, it starts to stumble or misfire. Then I ease off the accelerator pedal. Or, I quickly release the gas and then press it down again rapidly. Sometimes, the car will then immediately pull forward with full power."

Quote:

Suppose the intake manifold is cracked, would you be able to tell by smelling exhaust fumes? I'm asking because I think that exhaust gases might be entering the intake system through the EGR valve at idle or otherwise, or am I wrong?

This doesn't explain the sudden increase in boost pressure and the subsequent dip (at 1600-2300 RPM) either. In fact, it's a classic overshoot phenomenon, but not quite like what you might expect.

Read it again here: https://community.dieselschrauber.org/en/viewtopic.php?t=10810

The boost pressure delta (at a base setting of 1400 RPM) is sometimes as high as 265 mbar. According to a technical article, this is approximately 100 mbar too much.

We can't really assume that the VTG (Variable Turbine Geometry) is incorrectly adjusted, since it was already like this before the charger replacement.

But what about the control unit?
"With my Renault Laguna 2 1.9 dci, it was the case that it always ran roughly when idling with the air conditioning on. The suspicion initially fell on the injectors, but by chance and under strange circumstances...the engine control unit was replaced with a used one. Since then, the engine has been running smoothly at idle, even with the air conditioning and other consumers turned on."

Or is there a suspicion that no one dares to say ?

I'm afraid I'm back to the same place now... on the edge of doubt...

Quote:

We can't really assume that the VTG is incorrectly adjusted, since it was already like that before the loader change.

Yes, if it were a "different" one – but it isn't. It may have just been cleaned and the running gear replaced.

If, for example, something was previously misaligned on the VTG (Variable Transmission Gear),...


@Ulf, what do you think about that?

The car was a well-maintained Volkswagen vehicle until I received it. The problem wasn't always present, as far as I can remember. What I don't understand is why someone would have tampered with it. I mean, I had already inquired whether they could check or adjust the turbo settings, but I was always told "no."

EDIT: This car doesn't have something like a variable valve timing system, right? It has an 8-valve engine, not a 16-valve one.


INFO: Habe soeben mit einem Kollege gesprochen, der den Wagen meist immer hatte. Sure, please provide the text you would like me to translate from German to English.
The problem wasn't always present. It only occurred occasionally. It seemed to be more prevalent on short distances. However, it would sometimes disappear again on longer journeys.
The car, due to this occasional problem, was mostly used for short trips towards the end of its life. Towards the end, it was still there, though.

Could it be that the intake manifold is somewhat clogged internally? Although I couldn't see any huge deposits from the outside.

Hi @dieselschrauber, thanks for processing the differential pressure log.
Oh shoot, clumsy me. The log files MWB 10 & 11 are older (the DPF is full), I didn't mean to upload those.
Good observation, Autoservice! Is it possible to identify this in the newer differential pressure logs as well?
Would a specific boost pressure setting be beneficial again?

Here is the log again; I can see from it a short-term difference of over 500 millibars!
Then the load cell quickly drops below the target value and from that point on, it moves towards the target at a constant but very slow rate.
It's questionable now whether the control system is compatible. Otherwise, it seems to me that the loader isn't working correctly.
Unfortunately, I'm not familiar with KDataScope.

Ah, it's the same old story again.

BM, could you please also include the control mechanisms in your description?

If someone hopefully doesn't have a SAVING proposal by tomorrow at noon, then I will take this commercial vehicle apart tomorrow, carefully examine each part, send the turbocharger for inspection, and simultaneously work on the engine control unit...
Can the individual sensors be tested effectively? Regarding differential pressure sensors, if they are faulty, the issue should ideally be noticeable across the entire range, resulting in some performance loss. That's what the parts dealer explained to me today when I bought the turbo pressure sensor... Based on how I described it to him, he seems to rule out that particular component as the cause. So, what does a faulty differential pressure sensor feel like? The Caddy has power; we also checked that.
I will also remove the intake manifold.

Here's the translation:

"But how does that work with the engine control unit (ECU)? Elsa suggests that you need to create some kind of backup. Is that possible with VCDS? With my Renault, the ECU was reset to factory settings, and all you had to do was install it, and it would automatically configure itself. Apparently, that's not how it works with VW if the ECU is reset to factory settings?"

Where is the engine control unit (ECU) located exactly? Is it where the windshield wiper motor is?

Thank you all for your previous answers and tips, and especially to RedR32, who has been a great help; without him, I wouldn't be where I am today!

In the old logs, this phenomenon is even more pronounced in certain areas. I wouldn't be surprised if it's still the case now.

"Subjectively speaking," the VTG goes too far...

Quote:

Hopefully, someone will have THE saving suggestion by tomorrow around noon.

A second or third well-informed opinion could help him further.

Martin, please stop fiddling with everything else. All the adjustments have already been made.
Not only do I think that the turbocharger is not okay with the VTG (Variable Turbine Geometry), but that's where you should start investigating. I have experienced similar issues with my vehicles (which have high mileage on their turbochargers). Cleaning and mechanically treating the internal exhaust housing immediately improves the situation, unfortunately, but only temporarily.
Therefore, I advocate for a well-designed replacement charger where, for example, the vacuum sensor looks aesthetically pleasing and isn't rusty like yours.
I would recommend STK Turbotechnik.

Hmm, the car is currently running without any error messages, so it's pointless to worry about it.

So, I'll have the control unit checked after all.
There might be two sources of error now: the control unit and, possibly, the turbocharger, since there was no whistling sound before it was replaced.

The impeller blades appear undamaged externally, as you can see in the photo. The black spot is a paint mark from the manufacturer. It looks like a crack, but it's not. This picture was taken approximately 350 km after the turbocharger installation. I have now driven about 1500 km since the turbocharger was installed.

Hey everyone!

Autoservice wrote:

... A second or third well-informed opinion could help him further....

Neija, I do have an opinion, but whether it would be considered well-founded remains questionably .
Dr. Ulf apparently doesn't want to .

In a nutshell:
I also suspect that it might be related to the ATL (Arbeitsgemeinschaft Logistik) or VTG (Verkehrs-Transportsgesellschaft) legal department.
I would almost completely rule out a VAT (Value Added Tax) calculation error if nothing has been changed in the software. The regulation seems reasonable, even if it is somewhat delayed.

"@Martini, are you ABSOLUTELY sure that you got your own charger back, or could it possibly be a different one? Did you note the serial number and/or any unique scratches/signs of wear?"
As Red already writes, I would strongly advise against carrying out any further exchange transactions - which are completely pointless and lack any purpose - and instead invest more money in a NEW (!!!) ATL. This seems to me the most likely mistake when you read through these 3 pages .
"...and save yourself the money you'd spend on having things 'checked', because whether those checks are actually done thoroughly is always questionable."
Just one more comment about the photo you uploaded of the lighter and the "manufacturer's color blot": Either the person who refurbished it had some very good snuff in their mouth, or that's supposed to be a representation of the lighter's internals, which would again be considered sloppy workmanship!

Below, I've attached the last log again using DataScope, and the two markers are positioned at the SAME LOCATION for easier comparison!
@Red: Due to different scaling, it is not possible to quickly display the VTG control and LD actual values on a common graph.

Best regards from Munich!

EDIT: Made the screens smaller.