M52b28 engine swap for m50b25 with m50 electronics

[4dri4n]

Hi everyone! It's been a while since the last time.

I finally got to a point where I am really pleased with how my e34 525i m50tu performs.
Last thing I replaced was the clutch for a single mass Valeo, in place of an old dual mass LUK. Aaand it improved aswell. It seems like little steps help to bring back the car to perform as it should. However it is true that some sensors replaced with aftermarket brands were a step back. You have to keep all original if you want it to perform right.

Well, the thing is that even I am pretty happy with how it performs right now, I would like to go a little further and swap in an m52b28. However I dont want to deal with swapping the wiring harness and convert it to OBD2 yet. I will do because I am sure it is the way to go but right now it would be great if I could just swap the engine, turn the key and go.
Do I need to make some mod to the stock EPROM parameters or maybe get some WAR chip or something like that, or can I go with stock mapping?
Is there any possibility to harm the engine with the mapping of the m50tu or is it just a matter of better/worse performance?

[4dri4n]

Is there any thread with good available info about OBDII conversion on an e30 e34 or e36?

Anyone?

[tantumaude]

Why not go S50? No need to worry about OBD2 that way

[zkd]

you can do that. I have swapped my M50B25 with M52B28 kept all the M50 Stuff including the ECU, all the sensors, and the Inlet Manifold. the engine runs very smoothly, same horse power but you can feel the extra torque and less weight. about 50kg less cause it's aluminium rather that cast iron block.

I have had it for the past 3 years and it's running sweet.

so I do recommend.

[4dri4n]

you can do that. I have swapped my M50B25 with M52B28 kept all the M50 Stuff including the ECU, all the sensors, and the Inlet Manifold. the engine runs very smoothly, same horse power but you can feel the extra torque and less weight. about 50kg less cause it's aluminium rather that cast iron block.

I have had it for the past 3 years and it's running sweet.

so I do recommend.

That is definately great to hear. I would do it if I had no chance but to go with OBD1, however, if I could just swap in for OBD2 harness it would be great cause the electronics are much more powerful and optimized. You can get better performance, better torque and better fuel mileage with OBD2.
The problem is that I know it is possible but there is not much info out there about how to wire things to make OBD2 engine harness fit with OBD1 harness.
I dont believe it is so complicated to do, however, I dont know how to start... it is a matter of money. I know the guy who does this sort of things and flashes the ECU and EWS delete and so. But if I can do it myself it would be great...

[4dri4n]

Why not go S50? No need to worry about OBD2 that way

I dont have the S50 avilable here in Spain. We have s50b30, s50b32 and s54. S54 engines are relatively cheap. About 2000€ but is expensive to swap. Then there are m52b28 but its aluminium block and it is BS. I dont like it.
An e39 528i is about 1500$ but an m52b28 is about 1000$. Strange, isnt it? For that price I could buy one and keep the engine and harness and sell the rest of the car as spare parts and get back part of the money invested.
Meanwhile I could convert my m50 into a 3.2 liter or something and keep the car runing.
I got to a point that I truly like how my car performs even beeing just an m50b25tu. Its quick. It has vanos redone, new knock sensors, new single mass clutch (that was a great step forward; never going back to a double mass) and cooling system etc. Car runs great. But an m52b28 at 1500 rpms has the same torque figures as an m50b25tu at peak torque. That is crazy. A friend has an e46 330Ci and he just kills me everywhere... anyway, my car gets all the attention and is way cooler than his

[4dri4n]

Let me share with you guys two pictures one of mine and one of my friend's e34.

2502gy9.jpg

2a5ndyg.jpg

Great cars. The should have come with a b30 instead of a b25 :/

[zkd]

That is definately great to hear. I would do it if I had no chance but to go with OBD1, however, if I could just swap in for OBD2 harness it would be great cause the electronics are much more powerful and optimized. You can get better performance, better torque and better fuel mileage with OBD2.
The problem is that I know it is possible but there is not much info out there about how to wire things to make OBD2 engine harness fit with OBD1 harness.
I dont believe it is so complicated to do, however, I dont know how to start... it is a matter of money. I know the guy who does this sort of things and flashes the ECU and EWS delete and so. But if I can do it myself it would be great...

I planned an OBD II conversion you will need to establish a minimum of 3 buses M-Bus, K-Bus and Can-Bus. To do an OBDII conversion you will need to lots of things including but limited to:

- full Engine harness replacement
- Transmission swap as well as an engine swap
- Transmission harness replacement ( transmission talks to engine via Can Bus in OBD II)
- Cluster and and interior car harness. (Since the cluster on an e39 is different from the E34 and it is the main generator for M-bus and K-Bus you will need to do some wizardry in fitting it)

this is going to take almost a whole doner car gut it and place it in yours.

It would be nice to do but it's too much work and the advantage would be minimal in my opinion but you will be able to fit a newer Tiptronic gear box..

[4dri4n]

I planned an OBD II conversion you will need to establish a minimum of 3 buses M-Bus, K-Bus and Can-Bus. To do an OBDII conversion you will need to lots of things including but limited to:

- full Engine harness replacement
- Transmission swap as well as an engine swap
- Transmission harness replacement ( transmission talks to engine via Can Bus in OBD II)
- Cluster and and interior car harness. (Since the cluster on an e39 is different from the E34 and it is the main generator for M-bus and K-Bus you will need to do some wizardry in fitting it)

this is going to take almost a whole doner car gut it and place it in yours.

It would be nice to do but it's too much work and the advantage would be minimal in my opinion but you will be able to fit a newer Tiptronic gear box..

I know that guys who deal with this stuff, they get rid of all of that. They just use the engine harness, and make it compatible with the OBD1 car harness so you can still use your original cluster and so. Thats the point of an OBD2 swap. They modify the code in the MS41 module so you just have engine management stuff.
I don't want to deal with can bus stuff and so... it must be easier than it seems. I am pretty sure that there are people here on this forum that know how to do it, or where to get some info.
I don't how and when but I am sure I will do it. But maybe someone can put things easier to me.

Meanwhile, maybe I just go the way you did; just swap the engine in and done. I can always get a WAR chip and so...

[4dri4n]

Some members of the spanish bmw forum have solved my doubts.

From my research it seems that there are 2 options.It seams that the engine harness and the car harness are two different and separeted things mated by one connector. X20 maybe? I dont know.

N°1 would be delete EWS, flash the DME (the truth is that I dont know what that means LOL but its OK, it's just 300 bucks) and so and keep the original m50 temp sensor for the temperature gauge in the cluster. Find which wires of the car wiring harness correspond to the wires in the obd2 engine harness and then just plug in both connectors.

N°2 would be exactly the same but you keep the EWS black box or module or whatever and the origi al key switch with the key switched into 2nd position. You hide it somewhere and then just use your normal key switch in the e34 to turn the engine on.

Seems pretty easy. I didnt know it was that easy.