Hey All,
I am here purely on a technical standpoint. I done many engine swaps before so I am aware of what goes into it but this was my first time swap on a nissan so having some issues

Anyway, I did the swap for a friend of mine (wanted to save the money to do it at a shop so I helped him out.) His engine blew and tranny was going bad (why? im not sure, hes not that smart with vehicle maintence) so he bought one of those full JDM engine's from a local importer. I knew some of the sensors wouldn't swap over so I removed MOST of the sensors from the old engine (only the necessary) as well as removed the japan sensors for the US ones.

The swap was straight forward, original wire harness lined up everywhere and the swap was a complete success. (ALMOST) car started right up and idled fine (minus a couple dry rotted hoses and stuck thermostat) and the car is running. However I am having a lot of random misfire. if it means anything, I used the original engines injectors and fuel rail to avoid disconnecting the fuel system, original wire harness. The only thing wiring wise i used on the new engine was the injector sub harness which was identical and was easier than removing the full lower intake manifold. It was the same plug and play

Codes that I am pulling are
P0300- random misifre (no followup cylinder code)
U1001- which i have no idea. I searched and said could be aftermarket amp related but doesnt make sense

Does anyone have any experience with these JDM engines or have had similar issues with their car. Other than the misfire, the engine runs great, transmission and clutch are surprisingly good. Although my friend is not really paying me i still would like to do a quality job to help him out

 

crazy thought but did you try swapping over the coil packs from his stock motor to the new one. Also did you put new plugs in? I'm just going off the top of my head, never looked at a JDM vq.

Do they have the same injectors?

 

I used the stock injectors from the old engine because i know sometimes they are different. They plugged in perfectly to the injector sub harness so. I am gonna try the injectors from the new engine and see if that changes anything.

Also i kept the coil packs from the new (JDM) engine. I am going to try swapping all that over too.

I did swap the plugs because when I pulled the plugs I did notice that that cylinder 6 was oil fouled and corroded so it looked like the engine had to be running rich before

 

make sure you got coil packs 4 and 6 plugged in right. They are often swapped.

 

U codes are communication codes IIRC

 

HAHA that did it! thanks. i had to go to the service manual to confirm. Not sure why it was wired like that. The car is in limp mode right now and wont rev past 3000k but i have a few codes i need to clear. Just wanted to get past the misfire.

I saw that it says failed to communicate with ECM but what does that mean? The OBD2 port is failing to communicate with the ECM or the engine is failing to communicate with the ECM

 

I had the same code after swapping the crank and rods from a used Ultima VQ, and rebuilding the motor in my 350z (spun rod bearing)... A lot of people are afraid to do so, but i dumped some lucas injector cleaner into the tank and filled it up. I cleared the code and it never came back again. Engine purrs like a kitty now. The 350z doesn't really have much of a fuel filter, so eventually the injectors can get clogged, and I have a sneaking suspicion that Nissan doesn't list any approved injector cleaner, so they can continue selling their very expensive injectors. Give that a whirl. Best of luck!