BMW E46 m52b25tub to m54 swap

**beamersnbeer** · 09-06-2021, 12:28 PM

So, i recently did a swap from m52b25tub to m54b22 because i had to tear it apart and i also decided to do full restoration to the engine, new rod bearings, piston rings, all gaskets and seals, cranckshaft bearings etc.
there was not too much information about swapping a m52tub to m54 so i decided to post this

-First of all you need every m52 engine harness except the harness that comes to coils.
-It's pretty much plug and play, couple of connectors have to be modified (the ones that connect to the car).
-I'm at the moment running the m52b25tub dme (because i don't have the equipment to modify ews).
-Don't even bother trying to use the m54 manifold, you have to replace the throttle body to m52 throttle body because the m54 throttle body is electrically driven and the m52 is driven by a cable and no the m52 throttle body wont fit into a m54 manifold without adapter and as both m52tub and m54 has a disa valve it's not a issue.
-My car was an automatic before i got it, i did a manual swap earlier so i decided to leave the automatic gearbox control module on the car (only one connector needed) and again i don't have the equipment to code off the automatic files, I'll get it later on
-The m54 fuel rail is a dead end so it only has a feed line as m52 fuel rail has 2 lines feed and return
-The engine is running good although i have the m52tub dme

Oh and the engine isn't going to stay on the car more than just month or two

The car being worked on is a 323i 1998 and the engine is from my parts car 320i 2003