AFN Power Loss: Troubleshooting & Common Causes

Hello!
I've pretty much tried everything on my Passat 3B now!
First, I had the error memory checked - NO ERRORS.
Replaced parts: Turbo, Mass Air Flow Sensor (MAF), EGR valve, Wastegate valve, Catalytic Converter, all vacuum hoses (new)!
All cables have been checked for breaks and other damage!
Symptoms: Starts up a bit worse than usual!
The turbocharger isn't building up the correct boost; it's performing like a Passat with only 90 horsepower!
Increased fuel consumption: 7.5-8.5 liters!
When he starts again, he does very well, but only for a short time!
He then noticeably responds better to the accelerator! You don't always have to press the gas pedal all the way down!
At VW, they only said that it might have too little air mass or boost pressure; however, the mass airflow sensor is new, and I've already tried a different new one!! The pressure hoses are tight!!
The diesel filter is also new!
If there's air in the fuel system, shouldn't it be smoking or something?
My car doesn't produce any smoke at all, which is unusual for a 110 hp TDI.
I have checked the start date of the funding and the tax period, and everything is perfectly aligned!
I'm only thinking about the vacuum pump or the control unit now!!
or air in the fuel system.
P.S.: If it starts normally (which is very rare), it starts up perfectly!
It seems like it works reasonably well during longer stretches of winding roads.
Maybe someone here can help me!

Since everything is new and all the values are correct, it should work!

Okay, to be honest:

- Why did you change everything you wrote?
- What do these supposedly low values look like? (Also, even a new LMM can be defective.)
- Air in diesel fuel does not cause smoke.
- You can easily see air in the diesel fuel by looking at the transparent hose leading to the ESP (Exhaust Gas Recirculation) system.

Sorry, but the only thing that comes to mind regarding your information is:

He's probably broken.

If you have the opportunity, try a different control unit – or get VW to try one.

Based on the information you provided, it's impossible to make a definitive diagnosis online.
At most, it's a "I've been there" kind of statement...

m;

When I bought the car in August, it wasn't running properly. I initially suspected the mass airflow sensor (MAF), but I didn't notice any significant improvement after replacing it. So, I decided to replace the turbocharger and the catalytic converter at the same time.
The expected level of performance still hadn't materialized.
Replacing the boost pressure control valve didn't solve the problem either!
Sometimes, he puts on a really nice outfit, and he looks great!
During a test drive, VW discovered that the air mass in the affected vehicles was within the lower tolerance range (when the sensor is malfunctioning).
(I should still have the version from 1551.)
Since I plan to increase the engine's performance by using a chip and fuel injectors, I want to make sure everything is working correctly beforehand, otherwise troubleshooting will be even more difficult.

- Vacuum pump?
-Air in the fuel system? (Is that still a possibility?)

Hi,

Is the EGR valve not sealing properly, or is there a problem with the EGR control system?

You wrote "AGR new," but that doesn't clearly indicate whether you're referring to the exhaust valve or the solenoid valve used to control it.

The function of the AGR (Abgasrückführung) has a significant impact on the measured air mass.

Best regards,

Jan.

Hello,
'Sorry, I didn't replace the AGR (Abgasrückführung valve), but I temporarily bypassed it with a blind plug.'
I haven't tried the valve yet. Could the valve also affect the boost pressure?

Hi,

What exactly did you seal with a blind plug?

Should I install the vacuum hose before the canister, or a metal plate between the exhaust manifold and the EGR valve?

The latter eliminates errors related to the EGR (Exhaust Gas Recirculation) system (but must be removed again -> ABE approval), while the former remains ineffective if the EGR valve does not close properly.

It already affects performance (and turbo boost) because when the EGR valve doesn't close properly, the air mass near the soot limit increases, which then leads to a reduction in fuel injection.

You mentioned that exact issue (the insufficient air mass), and the mass airflow sensor (MAF) is new, so hopefully it's working correctly.

Best regards,

Jan.

I HAVE SEALED THE PLUG BETWEEN THE EGR VALVE AND THE SOLENOID VALVE!
I opened and closed the EGR valve using a screwdriver, but I don't know for sure if it's completely sealing.
BUT A FAULTY AGR MAGNET VALVE CAN LEAD TO INCORRECT AIR MASS VALUES!
- GREAT IDEA WITH THE METAL PLATE FOR THE AGR (I WASN'T EVEN AWARE OF THAT).
Sure, here is the translation of the text from German to English:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which means 'Sincerely' or 'Best regards' in English.

Hey vr6-tdi, is your Caps Lock key stuck?

WHAT IS A CAPS LOCK KEY?
WHAT I'VE NOTICED SO FAR:
At 2500 RPM, you would normally hear a distinct clicking sound from a relay when the engine is cold, but I only experience that very rarely.
Sure, here is the translation of the text from German to English:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which means 'Sincerely' or 'Best regards' in English.

Hi,

If you continue to write everything in all caps, you should expect that a) no one will respond to you anymore, and b) your posts will be deleted.

Caps Lock is the function that enables all-uppercase typing.

Regarding the relationship between AGR (Abgasrückführung) and air mass: Please reread my previous post carefully, and then read the technical article about AGR. You should then be able to find the answer.

Regarding your relay clicking: Search for "Nachglühen." This feature deactivates once the engine speed exceeds 2500 RPM, which should absolutely be avoided, especially when the engine is cold (because "Nachglühen" lasts a maximum of 4 minutes).

Best regards,

Jan.

Hi,

Does the fuel injector control valve in the injection pump function correctly? Has this been checked before?

Best regards, Christian.

Hello,
'No, I haven't checked it yet, because the air mass and boost pressure aren't building up correctly.'
'But is there a way to test the volumetric dispenser (using a fault detection device)?'
Sorry about the Caps-Lock key .

You can use the diagnostic tool in the measurement block to check the fuel injection amount in mg/h during a test drive. It should inject a certain amount of fuel at full load. If it doesn't get enough diesel, it won't have full power. If it's determined that this is a defect, you can contact a Bosch service center, as they can rebuild fuel injection pumps. This is often more cost-effective than buying a new one.

Best regards, Christian.

Sorry about the Caps-Lock key .

It is commonly referred to as screaming.

Best regards, WarLord.

Hi,

Thinking is not forbidden!

Have you ever considered that your insufficient air mass and boost pressure readings might be the result of a different cause, as suggested by various people on multiple occasions?

Okay, so: Find out how to check the mass airflow sensor (use the forum search function for this), and then think again about the relationship between air mass, boost pressure, and EGR. The forum search function and technical articles can also help with this. There's also a technical article on systematic troubleshooting.

Once you've gone through everything and are absolutely certain you've ruled out all the possibilities mentioned, please let us know what you've excluded and *then* we can help you!

Best regards,

Jan.

I just wanted to thank you all for all the answers.
ich werd diese woche wieder all das ,was ich hier gehört habe ausprobieren und hoffe ich finde endlich diesen sch... Error!!
Best regards, VR6-TDI.