I have recently replaced the fuel filter and added a fuel additive of my Cayenne, both are bought from Porsche company, but the very next day I drove my car and it starts to stumble and stalls. Would this be a clogged injectors and how can I resolve the issue?

  • 1
    I think is is more likely that you're pulling in air through a loose connection at the fuel filter. Does it idle well? Can you describe how to produce the problem? Does it actually stall (as in your have to restart the engine)? What fuel additive did you use? What is it's purpose (why did you decide to use it)? Many fuel filters have connections with O-rings, those can be a bit tricky to work with. Do you know if yours has them? Did you change them?
    – dlu
    Jul 25, 2016 at 21:38
  • I was driving normally when it started to hesitate and I felt the car is losing the power, the power was fluctuating. it actually stalls when I completely stop after felling the power lose, so i had to start the engine. I use Porsche Fuel additive recommended by Porsche itself. I used the additive after changing the fuel filter as the acceleration was not too good. the O-rings have been changed along with the filter.
    – Osama
    Jul 25, 2016 at 21:43
  • I'd start by checking the connections at the fuel filter. Can you add a link to the actual filter or a photo of it? If you're drawing in air it could cause symptoms like these.
    – dlu
    Jul 25, 2016 at 21:45
  • I have checked all connections of the fuel filter and found them OK. pelicanparts.com/catalog/SuperCat/955C/POR_955C_FULful_pg1.htm
    – Osama
    Jul 25, 2016 at 21:49
  • 1
    Any chance you installed the fuel filter upside down? If your issue started right after your fuel filter change and fuel additive, it's one of these two. Fuel additives are usually harmless.
    – tlhIngan
    Jul 25, 2016 at 21:52

1 Answer 1


There are a few potential issues as far as I can see. I'm drawing from my own experience with fuel systems and from a few of the comments.

First, is/was your tank full when you put in the fuel additive? Fuel additives should always be mixed into a full tank of gas. The best way to add it is have a half tank, add the additive, then top the tank up. You need to have it diluted by the gas. If you indeed have less than half a tank, try filling it all the way up to make sure the additive is diluted and mixed in with the fuel.

Next, double check all of the connections you fiddled with. Check that your connections are fuel-tight, and that none of the hoses accidentally got holes in them. Even a small bit of air or fuel leakage can cause major problems. I know you said you checked them, but check again.

Finally, make sure your fuel filter is the right way around. They only work in one direction, so make sure that it is oriented correctly.

Hope this helps!

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