Diesel Smoke

Power loss and smoke on my tuned diesel car?

At first, my car was OK after the tuning but now it has less power and more smoke. What can be the cause? Has the software changed?
No the software didn't change, but this can be caused by several problems :
  1. Is your air filter really clean? Some dealers wait more than 50.000 km to change it.
  2. Check or let your combustion recirculation system checked! This electronic controlled valve connects the exhaust with the intake in certain conditions for better emissions, but it can stay open the whole time. In that case, take the electronic connector off from the electrical valve and take the vacuum hose off the mechanical valve and put a plug in the vacuum hose. Or you can put a plate between the exhaust pipe that connect the exhaust gas with the intake manifold. If this valve stays open, you have a lot of black smoke and also power loss. This is a frequent cause.
  3. Another frequent cause is a faulty air mass meter. The problem is that it didn't give a fault on normal diagnostic systems, because this systems can only control the wires. If the sensor signal changes, it can change and give a wrong signal to the ECU. Most of the time when this is the fault, the power is OK until 2.500 to 2.700 RPM, but after that, there is a dip in the power curve and the car doesn't have its tuned power anymore. A dyno test can give you the answer.

Beware, these different causes are not specific to tuned cars, but can also occur in complete original cars. The only problem is that some dealers state that the power loss is caused by the tuning and don't want to help you.


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