2 battery CTT, should I disconnect both batteries?

[royxaxa]

I plan to replace the fuel filter for my 200k km CTT.

so my question is: should I disconnect both batteries or just the main one under the seat before I perform the service?

I noticed there is a ground wire out of the battery box under the driver seat. I assume disconnection of that one is equivalent to removing the cover of the box and disconnect from there.

thanks guys!

[Loren]

The rear battery is just for starting the engine - but to be safe I would disconnect them both.

[royxaxa]

thanks Loren. it is better to be safe than sorry, I guess.

another question, do you think fuel filter should be performed as a regular maint or only when there is a problem?

Cheers,

Roy

[Loren]

Supposedly the fuel filter (inside the fuel tank) never needs changing unless there is damage or external contamination.

Fuel tank re-calibration will be required.

[royxaxa]

thanks Loren

[ekstroemtj]

Supposedly the fuel filter (inside the fuel tank) never needs changing unless there is damage or external contamination.Fuel tank re-calibration will be required.

Loren would you please describe what means FUEL TANK RE CALIBRATION?Thank you

[JFP in PA]

Supposedly the fuel filter (inside the fuel tank) never needs changing unless there is damage or external contamination.Fuel tank re-calibration will be required.

Loren would you please describe what means FUEL TANK RE CALIBRATION?Thank you

You will need a PIWIS tester to calibrate it.1. Disconnect the battery and cover terminal or battery.2. Remove cap over the fuel level sensor system.3. Remove fuel level sensor. (attached to the fuel pump inside the tank).4. Using a fuel extractor, completely drain the fuel tank through the fuel level sensor opening.5. Make sure that the two recesses on the left and right−hand sides of the tank are emptied completely.6. Reinstall the fuel level sensor and, with "ignition off", fill the tank with 28 liters of fuel.7. Perform tank calibration with the Porsche System PIWIS Tester:· Select vehicle type (997TT)· Select control modules· Select instrument cluster· Select menu item "Tank calibration"· Confirm calibration8. The fuel level sensor system has now been calibrated.Be very careful when doing anything with the fuel system as there is danger of fire or explosion.

[ekstroemtj]

Great and thanks a lot.

One question left please. What is going to happen if you dont do this procedure after full pump replacement? I had a replacement of all parts at the shop some weeks ago.

Thank you

[JFP in PA]

Fuel

Great and thanks a lot.One question left please. What is going to happen if you dont do this procedure after full pump replacement? I had a replacement of all parts at the shop some weeks ago.Thank you

The fuel gauge will not read accurately, can also impact fuel usage calculations in the OBC system for that reason.

[ekstroemtj]

Thank you. If i get you right it doesnt have any impact to fuel pressure and driving behaviour of the car.

Many thankx again for your detailled information.

[JFP in PA]

No, it should not alter fuel pressure or driving behavior, just the fuel level accuracy and what the trip computer thinks is going on.