Hello guys! This is my first post here, i finally decided to swap my M43B16 to a more powerful M50B25TU Engine.


I bought the engine out of a 1991 BMW E34 518i (Originally the Engine was swapped from an 1994 E34 525i)


It ran perfectly 6 months now on the E34 that a friend of mine had and about two weeks ago the transmission failed and the car was parked, so i took the chance to buy the engine.


We sucessfully swapped it to my car last weekend and i noticed that the engine didn't perform as good as it did on the E34 which is a bit weird given the E36 is a lighter chassis.


The first issue was a rough first start (It cranked for a while and it slowly raised the RPM and then stalled) after few tries we managed to make it idle, which sounded really good without any hicups or misfiring, when i tried to give a small amount of throttle the car would raise the RPM without a problem, but when i floored it, it sounded like it was bogging, it held around 2500rpm and you could hear the intake getting air but it would hessitate and it would not raise RPM as if it was in some kind of safe mode, if i let go the pedal slightly then it would go up.



I took the car for a spin carefuly at first to make sure everything was bolted and connected properly and the first time i tried to floor it i realised the car didn't have much power.


At that point i want to clarify that my chassis is a 1997 OBD2 if im not mistaken and the M50 engine is a 1994 OBD1, i read somewhere that you have to connect the VSS but im not quite
sure.

The only mod i did on the engine harness was to cut the Pin 7 of the DME Immobilizer


I changed the MAF, CPS, TPS, Spark plugs, DME, ICV.


I removed the O2 sensor but i got the same issues


With the car idling i gave direct 12V power to the Vanos Solenoid but as seen on a YouTube video the RPMs should go down because the Vanos locks the Camshaft, but mine went slightly up.


I also checked today the ground wire of the engine and it was slightly loose, i tightened it but nothing changed.


I really don't know whats wrong, i'm looking for a local shop that has a round connector scanner to see if i have any codes but meanwhile i thought to post here in case anyone could help me..


Thank you.