Zu wenig Ladedruck <2000U/min, aber keine Ahnung warum | Posts 48+

Hi,
Yes, the intake passages are completely clear; I disassembled everything, including the intake manifold, and cleaned it all thoroughly!

Here's a log from the charger check, but the 1400 RPM setting was entered incorrectly. I'll try to get a more accurate log tomorrow!

http://www.geocities.com/sveng4h/LDDifferenz.xls

-Sincerely-,

Sven@G4H wrote:

Here is a log from the loader check.

Well, he doesn't look too bad.

"Our air handling unit sometimes only delivers a pressure difference of around 100 mbar at approximately 1400 rpm, while other times it reaches 200 mbar."
I don't know why yet... unfortunately, I no longer remember which logs indicate whether the engine was warm or cold.

In your case, I would next investigate the exhaust system/catalytic converter.

Hi,
"I went to a workshop (a DIY garage) today for a compression test, but they didn't have the right adapter, so it won't be possible until after the holiday. However, based on the values from the idle speed control, I think the readings should actually be okay, since the correction value is close to 0 for 3 cylinders and +0.4 for one."

Okay, I guess I'll have to unscrew the exhaust and cut the pipe before the catalytic converter. But how will I know if the catalytic converter is clogged or not? I have no idea what a good catalytic converter looks like versus a bad one!

-regards-

Sven@G4H wrote:

How can I tell if a cat is good or bad? I have no idea what a good cat looks like or what a bad cat looks like!

Try searching, I remember, for example, a thread with photos about a clogged catalytic converter .

Hello,
I found some pictures!
Can a faulty or clogged catalytic converter be detected based on emission test results? My last TÜV (technical inspection) was only 4 months ago. I'm still hesitant to remove the catalytic converter, and I've done some more research on how a clogged catalytic converter typically manifests itself, and it seems that the performance issue usually occurs at higher RPMs?

-regards-

Sven@G4H wrote:

I've done some more research on how a clogged catalytic converter usually manifests, and it seems that the performance is mostly lacking at higher RPMs!

That could certainly be a result depending on the catalytic converter's flow resistance.

However, it is also certain that the loader performs best when running at low speeds if there is no more gas brake located behind the turbine.

Whether one first notices a lack of power at higher RPMs (due to a clogged catalytic converter) or sluggish torque buildup in the lower RPM range may depend on individual perception and driving style.

Since I don't have any personal experience with aftermarket catalytic converters for TDI engines, I can't offer any further assistance from this point on.

Just unscrew the exhaust pipe from the loader. Don't worry, it won't be *that* loud.

Best regards, Rainer.

Hello,
Okay, so the Kat (catalytic converter) is now installed! Well, it's really just a matter of definition as to when a Kat is considered "bad"; I would say the carbon buildup is in the early stages. I'm going to have a workshop evaluate it right away and then see what happens.
Here's some more information for Ulf: In the flexible pipe, there is at least no throttle or constriction in mine; the inner diameter is the same as that of the pipe itself!

-regards-

Hi,
Okay, I had a VW master technician take a look, and according to him, the catalytic converter is okay! But now I'm thinking about emptying it, since it's not detectable during the diesel emissions test. However, I'm still struggling with my conscience about it. It would be great if someone could comment on this who has already done this, and especially tell me if you have more black smoke coming from the exhaust without a catalytic converter than with one.

-regards-

Sven@G4H wrote:

Here's another piece of information for Ulf: In the flexible pipe, there is at least in mine no throttle or constriction; the inner diameter is exactly the same as that of the pipe!

Thank you .

I strongly advise against removing the catalytic converter, especially considering regulations and permits. Furthermore, based on general experience, unmodified TDI engines do not perform better without a catalytic converter than with a functioning one.

If I understand Rainer correctly, he wanted to suggest that you try a test drive (away from public roads ) with the catalytic converter removed and potentially log the data from the lambda sensor.
If this doesn't result in a profit, the problem cannot be with the exhaust or catalytic converter, and there is no reason to verschandeln out the catalytic converter.

Hi,
Unfortunately, I can't drive without the exhaust; there are very sensitive people in my neighborhood, and also a police officer!

I just blew out the catalytic converter with compressed air, and I was amazed by the amount of soot that came out (highly recommend wearing a mask). I think it's verschandeln now, so I'm ruling out the catalytic converter as the cause of the performance issues! I'll be doing a compression test this afternoon, and I'll let you know what I find.

-Sincerely-,

Hi,
Okay, so the cat (likely referring to a catalytic converter) is reinstalled, but the initial impression is that it's still performing very poorly, and the LDA (likely referring to a diagnostic tool or sensor reading) confirms this, indicating no improvement.

Mal noch ne andere Frage, mein Auto ist ja Bj.1998 somit ein ALH der frühen Generation, hat sich in den Jahren danach wohl noch die Software verbessert? Gibt es so eine Art Softwareupdate für die VW Motoren spez. ALH?

-Sincerely-,

As far as I know, there's no way to update the software (SW) retroactively except by replacing the engine control unit (ECU) with one that has a newer software version (if a newer version exists, which I assume is the case).

vagtuning wrote:

As far as I know, there is no way to update the SW retroactively except by replacing the engine control unit (ECU) with one that has a newer software version (if a newer version exists, which I assume is the case)

.
Yes, there are several versions/snapshots of the data available -> at the beginning of this thread.

@Sven:
While your vacuum pressure readings from the charge air cooler don't seem to indicate a clear "broken" state, I can't properly evaluate them.
Have you already checked the pneumatic system for leaks or air leaks (see Hati's post)?


Sure, I will translate the text from German to English and provide only the translation without any explanations. Please provide the text you would like me to translate.
Seal the external pressure inlet (on the air filter).

Detach the suction hose from where it connects to the BKV hose.

Using a large syringe attached to the suction hose, create suction. Ensure that the vacuum within the syringe is maintained, regardless of whether the engine is running or not! (When the engine is running, seal off the connections at the air filter and bypass valve hoses.)


Don't forget the BKV hose.
In our 2001 ALH Ibiza, the vacuum hose had become hard and brittle -> leading to a pressure loss that varied depending on the day -> resulting in occasional misfires at low RPM and other fun quirks .


If you want to test the system by forcing it, simply seal off the external pressure inlet. This will keep the VTG (Variable Turbine Geometry) at its closed position (as long as there is sufficient underpressure / the AGR (Abgas Rückführung - Exhaust Gas Recirculation) must be reliably sealed!). Then, during a full-throttle acceleration in a high gear, starting around 1100 rpm, log the LD (Load Demand) until the LDA (Lambda Display Adapter) indicates approximately 1 bar.
Otherwise, with this "defect," only drive in the low RPM range (below approximately 1500 rpm), or use little throttle, and always keep an eye on the LDA to avoid excessive boost pressure! (After all, there's no need to unnecessarily trigger the limp-home mode.)

From the difference between the log data and the typical laser diode (LD) behavior, it should be possible to at least estimate whether the poor LD performance is caused by a hardware issue or by the LD control system.

Hi,
Unfortunately, I don't have any logs yet! But I re-examined the vacuum system. If I close the hose that goes to the air filter and suck on the hose that normally connects to the brake servo hose (or to the vacuum pump), I can initially draw in quite a bit of air, but then it gradually decreases. I think this is due to the vacuum reservoir, because you also have to remove the air from it first --> The vacuum system should be airtight!

If I keep the breather hose from the air filter closed and drive like that, it noticeably improves performance at lower RPMs, and according to the LDA (likely a boost pressure gauge), boost pressure starts building even at low RPMs! (At approximately 1500 RPM with full throttle, it's about 0.5 bar).

The BKV hose is very stiff, especially after the T-connector, but I think that's normal. It doesn't have any cracks!

"I've also noticed something else: when I connect everything as usual, and I let the car roll with the clutch pedal pressed down, and then brake very gently, it starts to jerk. It's not just the brakes that are jerking, but the whole engine (or at least it seems that way). Could this be related to the vacuum or the power brake booster, or is this normal? When I closed the hose on the air filter, this effect was much stronger!"

-Sincerely-,

Sven@G4H wrote:

If I leave the hose from the air filter

closed and drive like that, it pulls noticeably better in the lower RPM range, and according to the LDA, boost pressure builds up even at low RPMs! (at 1500 RPM full throttle, approximately 0.5 bar).
Oddly enough, your old logs show a pressure of approximately 0.5 bar at 1500 rpm as well, see the attached file (below).
What exactly should be better now?

Our ALH Ibiza definitely builds more boost in the lower RPM range.
The rotation of the wheels is the same for both cars, so it can't be the cause.
Once the desired pressure is reached, the duty cycle also largely aligns.
Previously, the regulation attempted to compensate for the lack of LD (local development) by implementing a lower TV (tax value) – so far, so good.

Do you actually notice a significant difference between the fuel consumption measured during refueling and the displayed average fuel consumption?

If not, I would again consider using the closed coupling system of the VTG, even if the older and newer } loader are set up "incorrectly".