Dealer told me to put lower octane fuel in my 997...
Ive noticed every time i start the car up after its been sitting for about an hour the car starts up very roughly and idles very roughly until its completely warm. also when i try to give it gas i press on the gas pedal and just about nothing happens. it feels like its being suffocated or something. i really have to floor it get any revs out of it at all and it is extremely difficult to be smooth with it actually impossible. anyways i took it to the dealer and they told me that there is something wrong with my high octane gas from shell. which i thought was completey and utter BS because my BMW 750iL requires premium gas and its been running perfectly on the premium shell gas. im thinking since there is nothing wrong with the gas that logically there is something wrong with my car or its computer or something. maybe its knock controll is not working right causing it stay in a setting suited for lower octane fuel? Anyways, any help would be much appreciated. Has anyone else had this problem? i feel like my dealership is just trying to get out of a costly repair or something. 
I don't think that's normal, we have pretty crappy fuel quality here in south africa, but my 997 doesn't seem to be doing what yours is doing... i think you should consult your dealer again..
He also mentioned that he had been chatting with an engineer from Porsche that was there, and was told that the Carrera S was truly on the ragged-edge with 93 octane gas, that 92 octane would hurt performance (the computer's knock sensor would dial back timing), and that 94 octane would actually enhance performance a bit. I told him that 93 is all we have down here, except for 100 octane Cam 2 that costs friggin $5.00/gallon. Anyhow, the message was, don't put cheap 92-octane premium in the car, it likes at least 93 or more. Of course, if you live in higher altitudes, that all changes. I'm in Florida, where a good tidal wave would have us all swimming. Your dealer telling you to use lower-octane gas is absolutely full of sh**. You've got a problem that they need to do a better job of diagnosing. I put Shell 93 in my Carrera S yesterday. It's running like a champ.
