My 04 Cayenne Turbo has had a random misfire code since I purchased it, the misfire is on Bank 2, cylinders 5,6,7,8. The car shakes at idle, and I have yet to identify what could cause this misfire on only one side of the engine.

I have had the coils and spark plugs replaced, and it didn't change anything. The fuel pump was replaced due to a small leak, no change with the misfire.

The previous owner had 2 fuel injectors replaced, knock sensors replaced, and intake manifold gasket replaced, as well as getting new valve cover gaskets, and having the valve covers and cylinder heads cleaned. According to previous service records, the misfire was solved after this servicing and installing new Beru brand sparkplugs...


I'm at a loss as to what may have caused this misfire to return, and only on these cylinders. Would greatly appreciate some input on this as to what it may be, thanks!

 

I would be looking at the valve/heads on that bank, too.

In all seriousness, you're going to need to do some troubleshooting, which is going to require quite a bit of measuring, logging, etc. It's probably worth it to just take it to a Porsche dealer and pay the $150 troubleshooting fee.

 

On a vehicle of that age it may be worth checking the Air/Oil separator diaphragm. You mentioned you had the valve cover seals replaced, but i assume not a new valve cover with AOS. I've run into similar symptoms even with new coils and plugs.

https://rennlist.com/forums/porsche-...ement-diy.html

 

Do you have a way to look at your Bank 1 and Bank 2 Fuel Trim #s as that may tell you something. Could be a vacuum leak on only that bank or a number of other things.

 

I would try the MAF. Give it a try