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2005 Cayenne S 53k miles Knocking at cold start up


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Hey Guys,

I started my CS yesterday and it began to shake and knock pretty bad! This has never happened before. I change my oils every 5k, I changed spark plugs and coils less than 5k miles ago, so thats not an issue. Everything is up to date. I ran for codes and nothing pops up. The only thing that does pop up is the knock sensor bank 2. That has been on for a while now but it doesn't seem to cause any driving issue. Is it battery? I haven't changed that, and I think its original as well. The CS sits a lot in the garage, that is for sure. The last time I drove it was over a week ago. After starting it yesterday morning, I let it warm up and it eventually fixed itself. I drove it to work and opened her up on the HWY as well to maybe get rid of any carbon in the engine. I use 93 oct as well. Now I hear a faint knocking sound from the engine. I rev it up and as the engine drops RPMs I can hear the faint knocking sound. DOes anyone know what this means, or what it could be? Please help!

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Had the same issue after having it in the shop for about a week for a bumper change. When I picked it up it ran really rough, with slight knocking-vibration and a strong exhaust odor.

I pulled over, disconnected-reconnected the throttle adapter, did the reset sequence, filled up with premium shell and let it idle for a few minutes. It ran normal after that.

I would guess the fuel pumps are the culprits as they've never been changed (the carpet's still intact) and its approaching 98k mi. It's an 04 S.

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Maybe it is the fuel pump. The knocking goes away once I reach operating temperature. It's very strange and I can't seem to figure this out. I made an appointment with my mechanic, he told me that it might be the valves? Not sure, he is going to check it out and hopefully figure it out.

Anyone else come across something like this?

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Ok, here is the update on what my issue was... I hope this helps anyone else that has been having this issue.

 

Took my CS to the mechanic. He had it for the day, did a bunch of tests on the CS. Nothing was wrong with the engine. Did all the tests you can imagine. What he found was bad fuel. Really, really bad fuel. I always put Shell Vpower in the CS. So my only conclusion here is that the shell station I went to last, is not putting the right fuel into there tanks. Scamming the system and we the customers are paying for it. Everyone, be aware of where you fill up. It seems not every shell station is the same.

 

What we did to figure this out is we added some Techron fuel system cleaner and I filled up at my normal shell. We also changed the oils and I used Castrol 5w-40 this time around. I called porshe and they said they have been using this thicker oil for sometime now and it seems to help the engine. I drove the CS all day long, put about 100 miles on it. I opened her up on the HWY as well. The next day, when the engine was cold, I started her up and she was quiet as she has been for the last 5 years. My CS only has 53k miles its a 2005.

 

Like i said this is my experience. My CS is running perfect, quiet the whole time. No more knocking, no more rough idle. No fault codes either.

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