Passat TDI: No Power After MAF Sensor Replacement

Hello everyone!

My Passat TDI (110 hp), manufactured in 10/97, with engine code AFN, is not producing its proper power. The top speed on the highway is approximately 150 km/h. It's even slower when going uphill.

I thought the 235 tires might also be to blame, so I got a chip.
installed. (Speed-Buster) After that, the car had power again. On the highway, it could reach approximately 205 km/h, and the acceleration was endless.
During a longer highway trip a few weeks ago, the speed suddenly dropped from 170 km/h to 120 km/h. Then, on the uphill section, I was overtaken by trucks.
(how embarrassing...)
I stopped at a rest stop and tried to find the problem. After restarting the engine, the car ran normally again until the next time I accelerated fully.
I tried the game 5 times, and then I removed the chip because I suspected the problem was there. But even without the chip, the car didn't run any better!

Upon returning home, I had the error memory read out at a VW service center. The result was an error code related to the mass airflow sensor (MAF sensor). Unfortunately, I cannot provide the exact error code.

Following that, I replaced the LMM with one from a salvage yard.
Performance without the chip is the same as before. With the chip (using the old settings), it's significantly better. However, a few days later, the performance drop reappeared when accelerating on the highway.

Now I've installed a new LMM (linear motor module). (This is my third one...). It's also a used part. The function was tested in another vehicle. (Everything is okay.)

The car still doesn't have proper power. When I accelerate in 3rd or 4th gear, the turbo kicks in abruptly around 1900 RPM. Without the chip, the car has almost no power.

Ich habe schon alle Unterdruck Schläuche geprüft, den Kraftstofffilter und Luftfilter erneuert. Lwithout success.

Regarding VW, I'm not interested in taking my car there right now, because they tend to replace parts unnecessarily (like the mass airflow sensor, turbocharger, etc.) without actually finding the real problem. This makes it very difficult to estimate the repair costs.
Some people from the forum have already spent a lot of money with VW, and...
The car still isn't working.

Is there perhaps an experienced TDI enthusiast in the Remscheid/Solingen/Wuppertal area and surrounding region who could help me out in my desperation? (Measuring boost pressure...)
Even helpful tips would be very helpful to me.


I hope you all have a lovely Whit Monday!
Best regards, Gerd.

Hi.

The VTG (Variable Turbine Geometry) system on AFN engines often malfunctions, which can sometimes trigger the engine control unit (ECU) to enter a limp-home mode --> resulting in reduced power until the next engine restart.

Perhaps you can draw a useful approach from this.

/viewtopic.php?p=1207#1207

For the dry check of the VTG (railway car):
Detach the hose from the charging port and, using a large syringe and a short piece of hose, draw the liquid from the port.
Observe the membrane rod: it should be able to be smoothly moved into any position by syringe without jerking or catching, and the total travel of the rod is approximately 1 cm.
You will probably notice something different... then --> see above.

Hello Ulf!

Thank you for your quick response.

Since I'm not exactly a professional mechanic, I need to start by...
Manual: 'Locate the parts: hose from the charging chamber and membrane rod.' I'll try that tomorrow.

I also read through the other posts.

Despite this, I would be very grateful for any practical help in the Remscheid/Solingen/Wuppertal area.

I would also appreciate any other advice you might have.

Is there a turbocharger rebuilder near me?
What costs would I incur if the turbocharger (VTG) were to fail?
(Material / Labor costs.......)

Thank you very much, Gerd.

Hi,

How long, i.e., how many kilometers, have you driven with your chip?

Sure, here is the translation of the text from German to English:

'Gr.W.'

Hello Wilhelm Busch!

I've been using this chip since around August 2001. Before that, I had driven approximately 20,000 km with the car.
From the chip installation, approximately 40,000 km. (With optimal performance and normal fuel consumption ). The car is driven 6 days a week, with approximately 25 kilometers driven twice a day (so it is always driven until it reaches operating temperature).
I also travel a lot by train. (When I have some free time, I sometimes take a faster train to let off some steam...)
My car has been experiencing performance issues for the last 8,000 km.
(also with the chip removed)

The car has now covered a total of approximately 130,000 kilometers.

Best regards, Gerd.

Just a tip: I think your intake manifold is clogged from the inside with blow-by oil and exhaust gases, which is reducing the cross-section. You can check this manually by disconnecting the exhaust gas recirculation line to the intake manifold and poking around in the hole with your finger. If you find a muddy substance, then as described above. Alternatively, you can use a diagnostic tool and read the measuring block data, specifically block 008. This block contains limit values for engine speed, desired amount, torque limit, and smoke limit. Compare the last two values; they should be 3 < 4 at sea level. Or do you live in the Himalayas?

Hi everyone,

Quote:

I think your intake manifold is clogged from the inside with blow-by oil and exhaust gases, which is reducing the cross-section. You can check this either manually by disconnecting the exhaust gas recirculation line to the intake manifold and poking around in the hole with your finger.

I would rather perform this inspection by removing the intake manifold before the exhaust manifold and then looking into the exhaust manifold, because in this way I can see the actual intake path for the charge air, instead of the (relatively unimportant) intake channel for the exhaust gases.
In addition, you have the EGR valve directly in front of you, and you can visually check its ease of movement.

Hello everyone!

I was away on business for a few days, which is why I'm only able to respond now.
First, perform a 'vacuum test' on the charging socket.

Since I'm not a mechanic, I first had to locate the charging port.
I then did the test (the engine was off!).
With considerable effort, the rod moved slightly upwards during the vacuuming process.
I wouldn't exactly describe it as delicate. After vacuuming, the rod immediately went back down, as if something was pulling it strongly from below.

Is that okay?

The thick hose that runs from the mass airflow sensor (MAF) to the intake manifold was slightly oily in the area near the turbocharger (not oil sludge or anything like that).

I think I'll have to get the car checked at VW.
Please give me some tips on how to proceed to reduce workshop costs.
to narrow it down. I'm afraid the workshop will probably replace everything that looks like it might be faulty. (LMM.............) The ideal solution would be to replace the sensor.

Is it possible to repair a stuck VTG (vehicle traction generator) if it gets jammed?

Best regards, Gerd.

Hi.

Quote:

With considerable effort, the rod moved slightly upwards while vacuuming. I wouldn't exactly call it delicate. After vacuuming, the rod immediately went back down, as if something was pulling it strongly from below. Is that okay like this?

The total travel distance is approximately 1 cm. To reach the "top" position (due to the spring inside the container), you naturally need to apply more suction than for the first few millimeters.
For exams, I always use a large syringe (50 ml or more) because sucking with my mouth is too much effort.

Quote:

The thick hose, which runs from the mass airflow sensor (MAF) to the charge air cooler housing, was slightly oily in the area of the charge air cooler. (not oil sludge or anything like that)

It probably wasn't about that, but rather about the intake manifold, because from there, soot from the EGR system comes into play.

Quote:

I think I'll have to get the car checked by VW. Please give me some tips on how to proceed to reduce workshop costs. to narrow it down. I'm afraid the workshop will probably replace everything that looks like it might be faulty. (LMM.............) The ideal solution would be to replace the sensor. In the case of a jammed VTG, is it possible to repair it?

Translate the following text from German to English. Provide ONLY the translation, no explanations.

/viewtopic.php?t=3011&highlight=vtgmembrandose

check and complete yourself!

"I experienced the exact same thing. While driving at around 150 km/h, the emergency brake suddenly engaged. In my case, it was the turbo hose that had a crack. You can hear it if you stand in front of the open hood while someone briefly presses the accelerator; you'll hear a strange hissing sound. It took me a long time to find it, as the crack was on the underside. And, unfortunately, it's not cheap to replace (76 euros for that stupid hose)."