Troubleshooting TB/DME codes

[93wolfsburg]

Needing some help with where to go on troubleshooting a P1502 code. I'll start off with the details on the car and then the troubleshooting I've performed so far.

The Car: 
2001 Boxster base, manual trans. The motor was swapped to a 2003 motor, also 2.7. I acquired the car 90% swapped. The car had been sitting for I'm guessing about 5 yrs when the previous owner's mechanic had given up on the swap/wiring. I used this site and other resources online to find the DME 7.2/7.8 differences and match up the correct wiring to where the car would crank. Was immediately obvious that I had gotten it all wired it up correctly hearing the fuel pump cycle and the throttle body whine as it waiting for key turn. 

Shortly after starting noticed that chocolate milk coolant was spewing out of the overflow bottle, I had another thread on here where I found the oil cooler was bad, while installing this i also noticed that the radiator overflow hose was swapped with the coolant bottle overflow drain hose (glad this was the case or I wouldn't have found the broken oil cooler until it was mixing pretty thoroughly in the crank case).  Now with all the fluids in sealed in their respective places I began the process of bleeding the cooling system per the bentley manual. Halfway through the warm up the car started stumbling, the check engine light came on, and the gas pedal became ineffective and like many of the P1502 threads on here wouldn't rev over 2k rpm.  
 

Troubleshooting:
-Immediately noticed no more whine from the throttle body with key on, suspected maybe my wiring was incorrect, went back and checked every pin, ohmed them out, verified the DME was feeding 5v to the TB. Everything was correct.
-Tried another known good TB

-Searched on here saw thread about B+ shorts and bad fuel pump relay. Tested those circuits. 
-Saw some people had success cycling the key a bunch of times, tried this, no dice.
-Using a Piwis setup from a friend ran codes, got P1502, P1517, P1516, when trying to clear them the software says its unable to clear them and occasionally get a P0638 in there.

-Using Piwis reading value from the pedal which showed what I believe to be a correct sweep from 0-100%
-Using Piwis read values on the throttle body, and manually moved the throttle plate, once again saw a good reading from 0-100%

At this point I'm leaning toward a bad motor driver in the ECU that's not powering the stepper in the throttle body. I really have no way of verifying this and I'd like to confirm the diagnosis before just firing up the parts cannon. 

[93wolfsburg]

also as i'm looking around online to find another DME, how difficult is it to adapt immobilizers, im seeing a lot of information thats saying just swap keys/alarm modules/dme's all together. In the vw/audi world if you have the right skc/pin code you can adapt immobilizers, is this the same with porsche?

[JFP in PA]

Both the keys and the Immobilizer need to be coded to the DME, which requires both a PIWIS system and the factory code ID tags for both, which you will never find with used components and why the recommendation to swap all together.  Porsche purposely made the system difficult to prevent vehicle theft.

[93wolfsburg]

Decided not to just go off what the PIWIS was telling me and get some measurements on my own, I unpinned the DME 7.8 wires connector C8,C24 for potentiometer 2,1 respectively and measured their voltage with key on. According a white paper I found on the Bosch throttlebodies these pots should be 5v-0v and 0v-5v ranges, sweeping through the ranges as the throttlebody moves so they should always be in agreement or within a specified tolerance of each other through the range. This doesn't match the 16v the DME is seeing.  At this point just planning to send it off to ECU drs.

 

Edited July 15 by 93wolfsburg