Hi guys, after browsing for a long time this is my first post in the forums. I will try to keep this as short and straight to the point as possible, so basically I swapped my 06 g35 coupe (revup) motor with an 06 350z (revup) motor, and it refuses to start up.
So back in October my 2006 G35 coupe 6mt started to burn through a ton of oil so I decided to replace the motor. I did some research and heard the same year, 6mt, 350z motor would work so I decided to go with that and found one with 40k miles. Had my buddies shop put it in and it would not start. I have now the original g35 engine wire harness and ecu in the car. I thought maybe it was due to the immobilizer so I brought my car to the local Infiniti dealership to have my key reprogrammed. Ended up towing it back to the shop and Infiniti about 3 times after some miscommunications, but after getting a new key and having it programmed it still would not start. We then tried an ecu, because it threw a cel, from a g35 laying around, didn't work. I then purchased a (used) ecu, and yet again, didn't work. I then shipped out my original ecu to have it repaired. The check engine light went away, but it would still not start.
I then decided to have it towed to a Nissan/ Infiniti performance shop about 2 hours away, as a last resort. They scanned the car and could not find the problem. There they tried a new IPDM, did some electrical tests, but they still cannot find the problem. They think maybe the shop that did they swap could've fried the ecu/ electrical system due to the battery being connected for the swap and the alternator hanging loose. This shop was my last resort as they are a well accredited shop but they have not contacted me in a long time, cannot find the problem, and are just letting my car sit. May be leaving some information out due to this being such a long process but any help greatly appreciated.