The Audi A5 3.0TDi Quattro with 240hp has to be one of the nicest cars we’ve worked on and we’re not just saying that because of the sheer beauty of the car either. The DPF is situated at the back of the engine against the bulkhead right after the turbocharger. This type of setup is most common (having it right after the turbo) as this is where the temperature is at it’s highest and the DPF works only in HOT conditions, however, they’re still failing none the less.
The Audi A5 we had come in to us was a 2008 model (57 plate) and had the DPF regenerated by the Audi Main Dealer but after a month of being back on the road, the light came back on.
The total time taken for the DPF removal session on this Audi A5 was 5hrs and that includes the programming and diesel injection tuning as well.
We start first by reprogramming the ECU to turn off the DPF settings, this will then allow the vehicle to start & drive without the engine management light or DPF light being illuminated on the dash. It will also prevent the vehicle from falling into LIMP MODE due to the DPF blockage. Once we’ve reprogrammed the ECU, we begin physically removing the DPF box from the exhaust system.
Being situated at the back of the engine, there is quite a bit involved in removing it because there’s a lot of sensors on this car and you really don’t want to knock one of them as you’re lifting it out. It’s best to remove both under guards as well as the subframe because there are bolts which are better accessed from underneath the car and it will make things a lot easier when putting the DPF box back together.
Once removed, we then secured the DPF box in our industrial pillar drill. This is where the brains come in. Our engineers will take precise internal bore dimensions from both ends of the existing exhaust system and then calculate the correct bore size required for optimum results. We’ll then proceed to bore out the unit on our industrial pillar drill to the specification required.
Once that process is complete, we then put the DPF box in our industrial parts washer and to finish up it is hand cleaned and blown dry to ensure all debris is removed prior to refitting the box back to the vehicle.
Once the box is refitted and the car is fitted back up, we then leave the vehicle to run for 5-10 minutes until it reaches the ideal working temperature at which point we then take it for a test drive, making notes of any flat spots in the revs and a smoke test.
The final part of this process is fine tuning the diesel injection system. This allows us to smooth out any flat spots and optimise the diesel injection system to match the airflow rate of the exhaust system to ensure that it doesn’t cause the vehicle to smoke. This is crucial to ensure the vehicle doesn’t smoke so that it can pass the MOT with no problems.
Once the fine tuning is complete, we take the vehicle on a final test drive and confirm the results. The customer requested we fine tuned his vehicle for economy over power as you can imagine it is already a very fast car. However, the end results confirmed a minimum of 35bhp increase with 10-12mpg better fuel economy.
Overall, it was a very exciting car to work on and the customer was pleasantly surprised at the increase in both power & economy and all in all much better performance.