turbofun

Hello everyone,
I am new, but happy to be here. My question is, for the other 996 TT owners out there did your car have what sounds like an intake resonance noise on light throttle at around 3K rpm? The noise I hear is very loud inside the car. When it happens if I give slightly more gas or let slightly off the gas pedal it goes away. Is this the stock air box, or possibly the stock exhaust. Also the car is very new so when it's driven it's pretty easy, but the most I have seen on the boost indicator is .6, even on cold nights. is this normal boost level or am I missing out on some. If the boost is normal, do you think a couple of gallons of 103 VP unleaded fuel added to the pump 91 octane might help see a little more boost.
Thanks for you replies.
MIKE

turbofun

Thanks for the reply cjv. I live in san diego so I have pretty good air so to speak. As of the last 2-3 months the highest octane sold at the pump here in town is 91 octane. It's a real bummer. I'll put a few gallons of the real good stuff in there(103 octane) and see what happens. How about the noise did you hear that with your car?
thanks.
mike

gtdrei

Mike,

There is a bit of an intake resonance noise in mine at 2500 - 3000 under light throttle, as well as a definite stumble. I have also experienced it in 2 other 996TT's I've driven.

Robin

Jack

Mike:

I believe the sound you hear is perfectly normal. Every car I've driven makes that same sound. Also, recommended octane for best performance is 93, with 90 being the minimum acceptable octane. You should see and feel a difference adding some unleaded race gas. Try some Unocal 100--I believe there are some stations in San Diego that sell it.

New '02 996TT Owner--selling my beloved 993TT

Steve N.

As others have suggested, I'm certain your boost is limited by the octane of your fuel. Best suggestion - move to another place in the lower 48. As to the resonance, I have not noticed anything of this nature with my car. Have other issues - notchy upshift to second gear, for example.

turbofun

As appealing as moving out of california sounds, at this point thats not an option. But keeping ten gallons or so of 103 octane around is. I can get it from a dune buggy shop in town. So before I fill up I will just dump two or three gallons of it in first and fill up the rest with the 91 to get an average of around 94-95 octane. That should be good enough. As far as the noise is concerend I won't worry about it. The car is still almost frightening fast. And untill it seems like a problem I'll just keep driving and appreciating my car. Thanks for all the replies.
Mike

BG

I had the same question regarding the boost on my car, as I understand it from Porsche's north east regional manager the maximum boost on the 996TT is .76 bar. The best way to determine the maximum boost on your particular car is to shift into 6th gear at a low rpm like 2500 and floor it. You should see .7 bar of boost. Boost pressure changes rapidly depending on a number of conditions however it is always higher at lower rpm and drops off as the rpm rises. According to Porsche you will see the highest boost around 2500-3000 rpm and being in 6th. gear will give you time to look at it before it changes. This was the recomendation of Porsche. Every magazine article lists a different max. boost number but the Porsche web site lists it as .8 bar, so I guess they are rounding up from .76. Enjoy

FixedWing

The noise you are hearing is the diverter valve. The diverter valve is leaking which makes the harmonic sound you hear. This is a common problem on the Turbo and on the Audi which shares the same design. Most people don't recognise what it is and just live with it. But eventually the leak will result in a loss of power.

S.

Pete.

Hmmm...I've seen .9 (WOT in fourth).

I question the accuracy of the boost gauges.