AEL 140 PS: Performance Issues and Solutions | Posts 64+

Hello everyone.
I came across this page on Google while searching for "AEL TDI problems," and I quickly skimmed through everything here because my car has lost pressure!
Okay, let me summarize briefly:
In August 2000, I purchased an A6 C4 Avant Quattro TDI with a 103kW (140PS) AEL engine and a 6-speed transmission, manufactured in June 1996, with approximately 95,000 km on the odometer. The car has generally run well: It was primarily used for long distances, covering nearly 60,000 km per year. I always warmed it up carefully, and when the oil temperature exceeded 80 degrees Celsius, I would drive it with full power. I used fully synthetic oil and changed the filter approximately every 18,000 km.
To my knowledge, everything is original, so there's no chip tuning. In the summer of 2004, I estimate around 265,000 km, I suddenly lost power on the A7 highway between Fulda and Kassel (those who know the route understand how to appreciate torque). I pulled over to the right and discovered that the old air filter, which was completely clogged, had torn, and pieces of it had gotten into the mass airflow sensor, clogging it. I removed everything, threw the air filter in the trunk, and continued driving. Since that point, I believe I've had less power. Also, I believe that since that time, the onboard computer has been displaying a fuel consumption that is about 30% higher, and it's also calculating the remaining range based on that higher consumption. In reality, I believe the fuel consumption has increased by about 5 to a maximum of 10%. Before, it used to smoke a lot, but now it only does so minimally.
In October 2004, I drove from Switzerland to Tuscany with a motorcycle trailer. After about 1,200 km of driving with the cruise control set to 90 km/h (due to that damn trailer), the engine failed near Modena ("Ferrari") at 289,147 km (a number I will never forget). The crankshaft was broken. So, I had a new engine installed at the Audi center in Modena, and of course, the clutch was replaced as well (a total of 7,960 euros, which I will also never forget). At my request, the turbocharger and mass airflow sensor were not replaced.
The new engine, after being properly broken in, has the exact same power deficit as the old one. I've now installed a different turbocharger => no change. I've also obtained and replaced the mass airflow sensor => no change.
Recently, at approximately 317,000 km, I took the car to a BOSCH service center (a contact of mine). We did a test drive with a connected computer: everything was OK (boost pressure, etc.), but the air mass per stroke was slightly below the target value, and the air temperature was not registering a value. However, when reading the error memory, there was no indication of the missing value. After about half of the test drive, we temporarily reinstalled the old air mass sensor, but there was no change, and the temperature value still wasn't registering. BOSCH initially didn't know what to do.
I don't want to work on the car myself due to time constraints, and I'm hoping to get some advice here on what I can do.
When I take my car to AUDI, I'm sure they'll rip me off and I'll still have the same problem.
I am very desperate at this point.
I'm shifting gears like a maniac, and on the A7, even Golf TDIs with 90 horsepower are overtaking me going uphill, but they're doing it smoothly. Then I'm about to bite the steering wheel, and tears are streaming down my face. Before, I wouldn't even shift into 5th gear in situations like this, and I used to get annoyed at people who parked in the left lane.

I'm at my wit's end. Does anyone have any advice? I'm so glad I found this page – it's like a support group for me!!!

Best regards,
Bernd.

Hi and welcome.

To begin with: Without actual measurement data (see technical article --> systematic troubleshooting with VAG-COM), we can only guess, more or less accurately, in this case.

Since you mentioned that the entire engine has now been replaced, but the problems are exactly the same, I assume the issue is not with the engine itself, but rather around it.

Since you mentioned that the air filter was torn and could have hit the mass airflow sensor, I would first investigate the entire intake path. I would check the air filter intake hose (to make sure nothing is inside that might have damaged the air filter) and then remove all the boost pipes (there are only a few screws) to inspect them for any bottlenecks. I would pay particular attention to the turbocharger inlet (though this is unlikely) and the intercooler. If the pieces of the air filter actually made it through the turbocharger and into the intercooler, they would likely be lodged there, causing a loss of power.

Generally, restrictions in the air intake system should become noticeable, especially at high engine speeds and loads (i.e., high air flow).

Furthermore, the LMM (likely referring to a specific component) might still be faulty. Some of us have already replaced it, but with little success, as the replacement wasn't working properly either. While it shouldn't be the case, it seems to be happening more often than we'd like.

Regarding the air temperature issue: Does your acquaintance have any idea what he was actually measuring? The background to this question is that a completely defective sensor should be stored in the error memory. If you knew which measurement block is missing the temperature data, we could provide more specific information.

Regards,
Guste.

Okay, even though the mass airflow sensor seems to be working correctly, the lower air mass and boost pressure could also be caused by a blocked catalytic converter! My friend had similar problems. Try removing the catalytic converter pipe and, if possible, shine a flashlight inside to check for blockages. Otherwise, remove the catalytic converter and test. If the performance returns, don't forget to install a new catalytic converter (tax evasion!).
Hopefully this helps you. FINGERS CROSSED. Oh, and in this case, there was NO error saved for my friend.