Hey everybody I got a 2008 G37S 6mt coupe, recently I got my car tuned from uprev at 320,000kms. Lasted for 2 weeks until i pushed it over 8000 rpms and had a bad sounding knock after that(I didnt know it could rev that high, my fault)

anyways I decided to swap the engine, called a place that parted out cars and they said they had a 2010 available with 158,000kms and came out of a 2010 6mt coupe.

I agreed and took it to a local mechanic to do the swap( just engine swap, I used my same ecu), everything fit, good compression, but they are having the following issue:

car starts but revs abnormally(rpms stutter aggressively and it also fluctuates between 1k to 3k rpms), clutch feels different, getting a code for the crankshaft sensor circuit A.(I went to infiniti and bought another crankshaft oem sensor and still getting the same code).

car is stuck at the shop, put in new MAF sensors and he used a regular scanner to do the relearns he did not do them manually. Also the check engine light comes on after having the car running for over 30 mins or so.

car has z1 cold air intakes, throttle body spacer, muffler delete and high flow cat with secondary delete.

please let me know if I am posting this in the right section.

the shop that sold me the engine says it fits and it's an issue with the mechanic not doing the swap right, the mechanic blames the part shop for sending me the wrong engine

lol.