Golf 4 TDI: Power Loss & Emergency Mode

Hello,
I've been reading for quite some time now, and I've even written something about the vehicle before, but it still isn't running the way it should.

Here's a brief overview of the current situation...

"Exhaust gas recirculation (EGR) valve replaced, completely clogged with soot, also the intake manifold was cleaned. As seen in the pictures in the technical articles, there were several millimeters of soot buildup."

Turbo replaced (the engine should have a turbo without VTG, but in any case, the pressure sensor was faulty and, according to various sources, cannot be replaced separately).

and the electric diverter valve (N75?!) was replaced.

After the new turbo was installed, the car started running a bit better, but it's now consuming significantly more fuel, about 0.5-1 liters per 100 km!

"Notlauf" still occasionally appears with the following error:

"Intake manifold pressure control differential."

Emergency mode, but not always! Only sporadically...

Today, we drove on the highway for a longer period, and at times, you're pressing the gas pedal all the way down, but the car just accelerates slowly.

Under certain circumstances that are not yet fully understood, and especially when accelerating, a significant cloud of black smoke also comes out from the back.

I'm planning to take another logging trip as soon as possible... maybe someone can give me a tip on what else I should check beforehand.

edit:
I just found the following in this article: (/viewtopic.php?t=3101)

Quote:

In case of incorrect charging pressure, the charging outlet for problem identification can be directly connected to the charger membrane sensor. If the boost pressure is accurately limited to approximately 0.6 bar, then the fault likely lies within the pressure sensor range. MSG / Solenoid valve / Hoses / Cables.

Can I do this without any issues on my engine? It's a turbocharger with an EGR (Exhaust Gas Recirculation) control system.

"Or something else... How can I check if the EGR pump is working?"

I am grateful for any advice!

Hi, here are the raw data in CSV format or a log file.

I'm not entirely sure about the exact gear changes, but where the section that takes longer, from 2 to 4000 RPM, would likely be in the 4th gear.

"With the second file, I drove it twice, each time from 2000 to 4000 meters, using the 3rd and 4th gears."

Unfortunately, there is no emergency exit available.

" color="red">Bitte keine Links zu externen Dateihostern! a) nerven die zusätzlich notwendigen Klicks, b) Wartezeit, Werbebanner/Werbepopups und notwendige Registrierungen, c) ist nach einiger Zeit die Datei weg und das Thema für andere Leser nutzlos!

Bitte nutze 'Attachment hinzufügen' bzw. das Upload Forum hier.

steve1712 wrote:

Hi, here are the raw data CSVs or log files. ...

Please upload the data to the "Upload" subforum.

Description of how to do it: https://community.dieselschrauber.org/en/viewtopic.php?t=12997


P.S.: Your engine should have a variable geometry turbocharger.

Hi, okay, thanks for the heads-up. I must have missed that. I was just wondering why I couldn't upload any files.

Here are the files:
Okay, I'm ready. Please provide the German text you want me to translate.

edit:

and no, he definitely doesn't have a VTG... the N75 is also correctly connected... and according to technical articles, it should be connected like it is for chargers without a VTG, i.e., with a wastegate.

Hi,

The AGR has a turbocharger with a wastegate. The boost pressure control seems good at first glance, but there might be a mechanical issue. Check the linkage and the pressure sensor.
"Power loss is unlikely. The mass airflow sensor is a bit weak, but it's just enough to exceed the soot limit by increasing the torque limit."
However, the throttle response might not be that great with this modification.

Best regards, Rainer.

Rainer K. wrote:

Hi, Possibly a mechanical jam; check the linkage and pressure sensor. Power loss is unlikely,

Hi, thanks for the info. So, the turbocharger is actually new, which means the wastegate is also new.

There could be a situation where the vacuum pressure is too low, or the charging limit might not be reached.

I'm especially surprised by the relatively strong amount of soot coming out the back.

It's also very puzzling to me why the N75 still occasionally ends up in the production line.

In my opinion, the TDI is missing about 20-30% of its power, and the typical turbo boost is completely absent.

Quote:

The relatively strong amount of soot coming out the back is surprising to me...

Then you should check the exhaust gas recirculation system and look for leaks in the charge air system.

-> Technical article.

Best regards, Rainer.

Okay, I'll take a look.
Is there a way to test the vacuum pump for the AGR (Abgasrückführung) system? This car has its own pump for it... at least, I think it's a vacuum pump.

edit:
Okay, one more thing... my girlfriend says the diesel particulate filter made everything worse. Is that possible? Has anyone had bad experiences with it?

Hello,


I've had the AGR (Abgasrückführung) deactivated for a while now... I disconnected the plugs from both pumps... for testing purposes (with an error code in the control unit, that's okay, right??)

In any case, the performance is still not where it should be.

What else can I do to get closer to solving the mystery?

Sure, here's the translation:

"Best regards and thank you for any help!"

Check mass limits based on air mass (measurement block ).

Best regards, Rainer.

Was the particulate filter retrofitted?
Could the drain or the cat be clogged?

Loosen the exhaust pipe behind the turbo and try it like that.

Hello, yes, the particulate filter has been retrofitted... I will also try to address that, it's a valid point.