cid042

Hi all,

I am having a problem with the display of the engaged gear on my Motec (2008 997 Cup). While driving, the dash sometimes displays 0. I let you imagine how disturbing it can be when it arrives elsewhere than in the straight... (shift lights...)

AFAIK, the engaged gear is sent by the ECU on the CAN Bus and not calculated by the Motec, based on the gearbox potentiometer value, which seems ok.

Here is an extract on my Motec datas, where you can see the problem on the main straight at Magny Cours (two laps superposed, on with and one without the problem).

Doas anyone have an idea ? (please don't tell me that I need to buy a Modas !)

Thanks in advance for your help !

Cedric

Permafrost

If you look at the 0:45 to 0:50 range, you see the gear bouncing back and forth between two gears, so the problem isn't just a drop to zero. I have no idea how the ECU records or notes the gear, but it sure looks like a short or broken wire or something physically wrong, rather than just a logic problem.

I would recommend reaching out to Motec Joe for his help in diagnosing this.

Jim

cid042

Well seen ! And now that you mention it, I remember seeing the dash display 2-3-2-3 or 3-4-3-4.

Let's check the wires, then. I hope that it is just a matter of a broken wire !

Thanks Jim !

cid042

Having had a second thought about it, and if it works like I imagine, the ECU "knows" in which gear the gearbox is with a potentiometer attached to the box (the one the service manual says you have to check for good setting regulary, in 6).

The measure of this potentiometer is provided to the Motec by the ECU via the CAN Bus and is logged on my datas under "Gear Pos volt".

Its trace seems good to me, so I don't think that it could be a short issue, but I am certainly missing something here, as, if it works like I guessed, if the Gear pos volt is ok, the displayed gear should also be.

I fear that I am going to have to follow the Bosch "black box" way... :-( Anyone have a flash file for a 2008 ? ;-)

cscrogham

The gear potentiometer on the side of the gearbox needs to be adjusted or replaced. Recently changed the gearbox? Prob just need to adjust. The poti isn't failsafe either, they go bad on occasion. There is a US source to avoid the markup from the US part that goes to Germany and then back to PMNA, each time with markup!
If you have that display on your dash page (gearsen) it should read 3.85vin 6th gear. I think the newer models replaced that with 2.64v in 3rd, but either number will get you close enough to solve the issue. It is a pretty simple matter of loosening the poti and turning until the proper # is displayed.
If you do not have the display on the dash, then you will need to get that enabled by a PMNA rep at the track. They will help you if you bring the car to them.
FYI the flat shift isn't working when the gearsen is off, careful of damage to the dogs.

cid042

Thanks ! Let's open the PC

No Porsche support at the track there :-\

cup997laurent

hi,
I checked the volts values in my motec and the values are more clean so it could be a wiring problem or the sensor itself .
i have a problem with the gear pos volts when going from 3 to 4 th gear some times ( 4.37 for ex ) or on others gears (before 3.50 ) any ideas ?????

cup997laurent

Salut,
on a tous des problèmes........

cid042

Thanks Laurent