so i’ve been searching the forum for a answer and i’m yet to find one so forgive me if it was already answered i’m just looking for a little clarification.
so i have a early 03 AT sedan (2003.0) and the mileage is up there so i’m looking to swap the motor before it gives out on me.
As we all know the early sedan is plagued with the early style ECU (one connector) so my question here is would my only option to swap another VQ35DE in is to find another one that came from another AT 2003.0 sedan with the same ECU? it seems like the case, giving i wouldn’t really wanna have to mess around with swapping the ecu/harness(forums made it clear it’s not really worth it)

 

You can use any of the transverse mounted non-revup VQ35DE engines. 2003-2007 5AT or 2003-2004 6MT equipped G35, 350Z, M35, or FX35 would be suitable donors.

The engine itself is the same with the exception of the early models using a mechanical fan and an electric fan, newer ones used dual electric fans and the mechanical fan location was turned into an idler pulley. You will keep your existing mechanical fan pulley and bolt it in place of the idler if you get one of the newer VQ35DE engines.

The 6MT newer ones have what's called the "rev-up" VQ35DE engine, that will not work. It's easy to identify though by looking for the "waffle print" on the front of the cam actuators, here is a picture.



The cover on the right is the rev-up, you want the engine that looks like the one on the left which has a smooth cam cover with that single raised line.

6MT or 5AT doesn't matter, you will need to pull the crank pilot bushing on a 6MT (the 6MT transmission input shaft would fit inside this) and put your existing crank plug in it's place. If you get one from another 5AT it's going to already have that crank plug in place. I think technically they call it a 5AT pilot bushing, but it's not actually one, it's just a metal plug that you hammer into the center of the crankshaft.

Just make sure to keep all your existing stuff from your car and only use the engine long block from the donor. Keep your existing injectors, coil packs, all sensors, throttle body, cam and crank sensors, EVERYTHING. You don't know what condition the ones on the donor car are in.