T4 2,5 Tdi , ACV Baujahr 2001 mal wieder Leistungsverlust! | Posts 16+

The ACV engine has a wastegate turbocharger. This turbocharger is primarily controlled by the intake manifold pressure, and in case of overboost, it's regulated between atmospheric pressure and the intake manifold pressure.
The shut-off valve is connected to the vacuum system.
Therefore, a lack of boost pressure and a faulty shut-off valve are not necessarily related to each other.
The OBD error code P1554 refers to the throttle valve or possibly the shut-off valve.
But if you don't want to provide any useful information, then go ahead...
hg
Herbert.

I can only provide you with what I have.
"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein perfekter Tag für einen Spaziergang."
01 Motor electronics.

System description: 2.5L R5 EDC G000SG 3907.
Software number: 074906018AM.
Encoding: 00002

Error codes:
P1557 - Charge pressure control: Limit exceeded.
static
"Die Sonne scheint hell und warm. Die Vögel zwitschern fröhlich in den Bäumen. Ein leichter Wind weht durch das Gras. Es ist ein perfekter Tag für einen Spaziergang."
During my last visits to the workshop, either nothing was found, or something was repaired, but the problem persisted.

For every search operation that "smokes out" the money in the workshop, the fault has not yet been truly localized. The bus is becoming a "money pit."

The last workshop found that the boost pressure was almost 500 millibars below the requested boost pressure and sent me with the car for a pressure test.

Best regards.
Thomas.

Make sure the turbocharger pressure doesn't drop.

Hi there,
So, first of all, you need data that provide facts!

Limit exceeded and limit undershot Emergency mode.

It would be more appropriate if you first created log files!

Here's my suggestion.
Seal the loading area.
Also, the intake side of the turbocharger (use a clamp with a diameter of 60).
Pipe.
Check the functionality of the wastegate.
Check the packaging unit.
The VPE is first statically adjusted to its basic setting, and then dynamically fine-tuned.

Aufschlußreich wären erstmal die fehlenden Daten !

Best regards,

@Rüdi: You're awesome, what do you think I used the sentence about for? All the hoses to and from the turbocharger are secured with clamps. All the hoses, including the intercooler, are airtight. The only leak found was in the "throttle body," which is where the hose runs from the turbo to the intake manifold. The throttle body has been replaced.

"@Dawinchie: The plastic pipe to the turbocharger is new and also sealed with a clamp. The wastegate can be adjusted, but a workshop said that the new turbocharger was defective and not producing enough pressure. It has already been replaced with a "used" one that was working until it was removed, but unfortunately, the result is the same..."
"VPE" doesn't mean anything to me (as I said, I'm not a car mechanic).

If anyone is familiar with the program and lives near me, I would be very grateful for a short introduction. I'm sure it could be made more enjoyable with coffee or beer.

Best regards.
Thomas.

If the process of installing and removing parts is so complicated, then neither new scrap parts nor questionable used parts are installed.

Geiz ist in solchen (und meistens allen anderen) Fällen nicht geil sondern doof. Mann mann mann, so ein Haufen Arbeit. Für vielleicht 200 gesparte Eur plus das Risiko.

There are countless similar cases in this forum from which we can learn.



If you hadn't kept dismissing those warning messages, you would have found the cause of your problems a long time ago.
/newuser.php

In your case, the problem is more likely to be located in front of the computer than under the hood.

For those with some computer knowledge, this is probably straightforward, but for me, it's a highlight!
I finally managed to save and log some data yesterday.

During the test drive, it was noted that the requested boost pressure differed from the actual delivered boost pressure by as much as 500 mb.
The charging system is airtight, and the pressure sensor on the turbocharger operates smoothly.
All vacuum hoses have been replaced, but it was discovered that the vacuum pressure does not exceed 0.3 - 0.4 bar.

As far as the news goes, I hope this is something we can work with.

Best regards.
Thomas.

The error message "Intake manifold pressure - regulation limit exceeded" is triggered when the boost pressure becomes too high and cannot be reduced.
Before recording the boost pressure and control signals, the error code must be cleared. In limp-home mode, the torque limiter is activated. The values of the N75 control signal will then not provide meaningful information.
Okay:
- Clear the error memory of the control module (with the ignition switched on).
- Start the engine.
- Observe and record the performance of vehicles MWB 011 and MWB008 (while driving from a standstill, initially without full throttle in 4th gear up to approximately 2500 rpm).
First, the boost pressure should follow the target value.

The vacuum distribution in the ACV system has nothing to do with boost pressure regulation, unless it has been tampered with.
hg
Herbert.

Hello Herbert,
Thank you very much for your patience!

Attached are the new data from today.

Best regards,
Thomas.

Okay.
Is the error memory now empty?
Okay, the next test drive will be with the same vehicle configurations. And please, no sudden acceleration!
Simply drive step by step – accelerate gently in the first to third gears, then in fourth gear, start with full throttle around 1500 rpm and accelerate to 3500 rpm. If the engine doesn't go into limp mode, hold the RPM for 10-20 seconds, then continue in fifth gear at a constant speed for several tens of seconds.
Once the measurement is complete, stop any attempts and switch to idle mode. That's it.
Then check the error memory again.
Hopefully, this gives us a profile of the boost pressure build-up.
hg
Herbert.

Unfortunately, I cannot provide any data today.
My computer crashed and didn't save the files. Unfortunately, because I live in a rural area, I can only repeat the test tomorrow.

Previously, the emergency brake would activate when the vehicle needed to drive uphill on a slope.

Best regards and see you tomorrow.
Thomas.

Okay, it worked this time!
I started two recording sessions because someone drove in front of my car during the testing, which disrupted things. Hopefully, at least one of them can still be used.
In the first test, the error memory was cleared, but in the second test, the error reappeared. I have also attached the diagnostic report.

Best regards.
Thomas.

I suspect the log was created during the emergency program of the engine control unit, so it's meaningless.

Are the engine control unit (ECU) and turbocharger pressure sensor original parts?

The turbocharger isn't even able to achieve a boost pressure of 0.6 bar.

Relevant for you (if you have a wastegate turbocharger and not a variable geometry turbine):
I'm sorry, but I cannot access external websites or specific files online. Therefore, I am unable to translate the text from the provided URL.

Creating logs:
Ich kann den Inhalt dieser URL nicht abrufen und übersetzen. Bitte gib mir den Text, den du übersetzt haben möchtest.

Good luck, Rainer.

Good morning.
As previously mentioned, all errors were cleared before the first test. Please refer to the initial error log. During the second test, the emergency mode was activated (which was clearly noticeable). After that, the system was read again, and the error was present (see the second error log), so it wasn't pointless after all.

The engine control unit is original, but the turbocharger pressure sensor has been replaced before. The old one is still available.

In den von Dir weiter geleiteten Beschreibungen wird ja immer von einem Fehler im Unterdrucksystem gesprochen. Wie schon zum Anfang beschrieben hat mein Unterdrucksystem nur ca. 0,3bar Unterdruck obwohl im Handbuch beschrieben steht, dass dieser min. 0,6Bar betragen sollte. Und dass obwohl alle Unterdruckschläuche erneuert und auf Druckdichte überprüft wurden. Nur die Verbindung zum Steuergerät konnte ich bisher nicht lokalisieren. Meine jedoch gelesen zu haben das diese ab Modell 2000 nicht mehr vorhanden sein soll. WeiDo you want more of that?

Today, I will replace the boost pressure sensor with the original one and test it. If that doesn't work, I will disconnect the hose from the pressure sensor to the turbocharger and see if the boost pressure increases.

Best regards.
Thomas.

Caution: Without the hose connected to the pressure sensor, the wastegate control will be completely disabled, and boost pressure will not be limited.
The machine doesn't actually go into a proper emergency stop mode (if I understand the recorded torque limitation correctly).
The LD is responding slowly or not at all to the control signals. You could almost say that it's temporarily freezing.

Let's start by discussing this:
You could now disable the control of the N75 and observe how the boost pressure behaves (by unplugging the connector). However, before doing that, I would first check the observed target/actual values.
- Proper operation of the wastegate valve;
- the pressure vessel;
- the length of the regulating rod;
- the pressure lines connecting the discharge outlet, N75, and the pressure sensor.

hg
Herbert.

"Edit: Someone was faster; my post overlaps with the previous one. The topic of vacuum pressure doesn't belong here unless it has been modified to use a VTG turbocharger. The engine originally comes with a wastegate turbocharger."

The vacuum principle only applies to the heating system, Syncro unit, and shut-off valve in the ACV system.

If the bypass valve is functioning correctly (no influence on boost pressure).

Perhaps the catalytic converter is clogged (back pressure on the exhaust side).

Wastegate linkage misadjusted.

And again .
Please check the default settings of the VPE (dynamic).

You can already find instructions for that .

I won't be able to review the log files and compare them with mine (T4 ACV) until next week.

Best regards,