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Originally Posted by rbennett
Not saying I am an experienced Porsche driver  but Iwill agree, if I know my RPM, I know my true MPH! |
Hi,
You bring up a good point about
True MPH, because all Boxsters (perhaps 996/997s as well) are always 3-5 MPH Higher than actual speed (I don't know if this value is linear or varies with Speed). Porsche calls this a
Safety Margin.
I'm not sure if it's there intentionally to aid in avoiding speeding tickets or whether it's a product of the Sampling Rate to the DME. In any event, it's there.
Owners of '97-'00 Models can see the True Speed of their cars (and a lot of other interesting information) by accessing the Data Stream, or CAN Interface, on their Climatronic (Climate Control) Display. This True Vehicle Speed is expressed in kph (multiply X 0.621372 to = MPH).
To access this Data Stream, you put the Climatronic into it's Diagnostic Mode. to do this, Press and Hold the Reciculating and Air Up Buttons for 5 sec. The +/- Buttons scroll up/down through the list of 'c' codes. The Center Vent Button switches the Left Display between the 'c' Code and it's actual Value. The 'c' Code for True Vehicle Speed is - 20c. This True Vehicle Speed is updated 1/sec. To exit the Diagnostic mode and return to Climatronic Mode, press the Auto Button...
Happy Motoring!... Jim'99