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 10-09-2017, 11:54 Subject: Audi A4 B7 2.0 TDI: My Problem Car |
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Hello, since mid-June, I've owned an A4 B7 2.0 TDI with the so-called "great" BRD engine. Right off the bat... if I had known about all the problems this engine causes, I probably would have chosen a different one. 
The car has now covered 227,000 km, and I've added 4,000 km to that. Since I've owned the car, I've only used "Ultimate Diesel" fuel to prevent the injectors from becoming clogged too quickly.
The following items have already been replaced/renewed:
- Regenerated DPF from Artmaxturbo.
- Lambadonde by NGK.
- Temperature sensor BEFORE the turbocharger (original).
- Comprehensive inspection including ALL filters (including the diesel filter).
- Compensation wave module revised.
- many, many minor visual details.
Unfortunately, I'm having a problem with the DPF and I'm not entirely sure what's going on, and I'm starting to feel stuck. That's why I'm looking for tips and possibly some help here.
Since I am unfortunately not allowed to write in the actual Diesel forum (I lack the permission and I don't understand what I'm supposed to do there)  , I'm writing here. I hope this is okay; if not, please move it or explain to me what I need to do to be able to write correctly here. The forum has already helped me a lot just by reading it.
Now, I have to admit that I'm a trained automotive mechanic and I've been tinkering with cars my whole life, but the DPF and all its intricacies are completely new territory for me.
On June 19, 2017, I purchased a refurbished diesel particulate filter (DPF) from Artmaxturbo for my A4. The old filter had reached a load of 68 grams after 223,000 kilometers. Although the DPF light didn't come on, I wanted to do something good for the engine and replace the overly full filter.
A week later, the filter was installed. This included a new oxygen sensor, a new differential pressure sensor from BOSCH, and a new exhaust temperature sensor BEFORE the turbocharger (original Audi part).
After installation, we wanted to reset the ash mass to 0 using VCDS, as described in the instructions, but it was already at zero. I saved the value of 0 again just to be safe, and I've driven about 4000 km since then. The car averages 7 liters per 100 km. With extremely economical driving, it's 6.5 liters, but it's also possible to exceed 8 liters without any problems. (IS THIS NORMAL??) I'm used to my A3 8L 130PS with its "Pumpe Düse" engine consuming 5.5 liters in EVERY situation.
Was mir schon immer sehr komisch vorkommt ist das hohe Standgas von ca. 900 u/min. Ich finde es sehr hoch und dachte anfangs es liegt am vollen Partikelfilter. Aber auch nach Einbau des neuen blieb es unverändert. Is that normal?
At first, I didn't notice it as clearly, but eventually I realized that when the engine is running in regeneration mode while driving, it runs very poorly. This is probably a "problem" with pump-injector engines with a DPF (unfortunately, not the only one).
"I became suspicious when the car seemed to be regenerating its DPF "frequently," even with a new one. After the car sat in the driveway with the DPF light illuminated after just 3 days of city driving, I started using VCDS to read some diagnostic data and investigate the issue further. And that's where my questions come in."
Depending on how I drive, I can only travel a maximum of 300 km by car before the regenerative braking system kicks in. Is that normal? I thought it would last longer. My commute to work is 25 km each way. This includes 3 km of country road to the highway, and then 22 km on the highway at a leisurely pace (100-130 km/h). I usually drive within the engine speed range of 1800-2000 rpm.
After driving almost 4000 km, the VCDS software shows that the ash mass is 1.16 grams. However, the ash learning value always remains at 0%.
Two days ago, a faulty mass airflow sensor suddenly appeared in the error memory. It indicated a short circuit to the positive terminal, occurring sporadically. I immediately ordered a new one from Bosch. However, I've been wondering since then whether this faulty mass airflow sensor could also be related to the other abnormal behaviors I've been experiencing.
Differential pressure when ignition is ON is 0.0, and the offset is -2 mbar.
When I fully accelerate in 5th or 6th gear, the boost pressure goes up to approximately 1000 mbar.
My lambda values reach approximately 1.4-1.6 at full load in 5th or 6th gear, but they increase to 5.0-15.0 when the turbo is disengaged or at partial load. I find this very strange.
Yesterday, I drove 10km with the mass airflow sensor (MAF) disconnected, and the car noticeably pulled better in 5th and 6th gear compared to when the MAF was connected. The difference isn't as noticeable in the first 4 gears.
Yesterday, while I was performing a calibration test, the load coefficient was at 6%. Suddenly, the value jumped to 20% and remained there. This morning, after driving 50km, it's at 37%, and I think it will regenerate tomorrow. Since the last regeneration, only 150km have been driven.
Could all of this be due to a faulty mass airflow sensor (MAF sensor), especially since it's the original one from 2006? Or could it be something else? I would really appreciate any tips or suggestions.
Best regards, Christian.
Translated on 01-10-2026, 13:40. |
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