[Qmulus]

I see no reason to keep the stock DME, nor connect to the powertrain CAN bus for that matter. What information do you think you need to transfer from one system to the other? The messages that the DME would generate just aren't applicable to the electric motor, other than the RPM. My guess is that the display you are talking about already has the motor RPM. The DME calculates RPM via the flywheel 60-2 tooth pattern, so at a minimum you will need to keep the flywheel and sensor and connect it to the DME.

Considering that you no longer have a working drive train, the only way to get the CAN message information (IMO) is to sniff a working/running vehicle to see what exactly is needed. There really is no other way, unless you find someone who has done it and will give you the information. Companies like MOTEC and AIM have that information for their race displays, but they don't make it public. You will no find a Porsche spec that just lists the message structure and required messages. It would be a big effort to reverse engineer it. BTTT. Years ago I helped a company that was trying to do a similar conversion using a new Mercedes SL. They stripped out the drive train, and installed the electric motor, controller, etc., THEN thought about integration. Whoops, too late. That should have been done BEFORE taking it all apart. I helped them start analyzing the CAN data from another similar car so they could program a separate module to keep the chassis happy without the engine and transmission controls. They hadn't budgeted for my services, so I wasn't there long. Just enough to get them going. I don't know if it ever got completed properly.

My guess is that your car wasn't running when you decided to convert to electric, so getting data from your car likely wasn't possible. The good news is that the Boxster is pretty simple. I honestly think that you can do without the CAN integration. Sure, you will have fault codes in the ABS and instrument cluster for no communication with the engine controls, but everything will work other than the tach and misc. oil pressure, temp and charge indicators that aren't applicable to your system. Might as well take the LEDs out for those. I would not leave the DME in just for that stuff. It might not be too difficult to figure out the engine RPM message and use the EV controller to put that on the powertrain CAN bus. My bet is that you won't bother...