Help required rewiring/reassembling M42 engine

[Matd]

Hi all,

A quick introduction to my situation:
A few years ago I purchased a BMW02 that needed a lot of restoration.
The engine was completely shot (rusted from inside out).
Because an M42 engine swap into an BMW02 is not unusual and because of friend of mine had an M42 lying around, I choseto put this engine into my 02.

The bodywork on the car is now almost finished.  Next step is getting the engine running again.
As you can see from the pictures (see bottom of post) all the wiring connectors, intake runners,... is unmounted from the engine.
Furthermore I think someone did some work in the wiring loom in the past.
I'd like to get the engine running while it is not in the car as I expect it won't be easy to get it running plus with the engine in the car it would only make things harder to work on it.

I think the first step is list what I have and what I don't have (parts list).
Could anyone point me in the right direction on this? What reference manuals do I need. Maybe some online documentation?
+if some of you think it will be VERY HARD to get it running again I'd also like to hear it (just to know if I have to find another solution).
As a side note: I have an electromechanical engineering background so I am not a complete novice .

Thanks!

[DesktopDave]

Looks like you're pretty complete there. I'd take this chance to convert to Rob's COP setup, if you can find one. It uses a custom mounting plate to mount four cheap M60 COPs, eliminating the costly plug wires and old M42 coil packs. I'm worried about the height of the DISA-style manifold. If you don't have enough space, swap to the earlier one-piece unit. You'd need the complete intake since (I believe) the fuel rail and ICV mountings are different. The rest just bolts right on, including the TB and injectors.

Everything else should work AFAIK, but I've never done a swap like this myself. JakeB is the expert, he's put a few M42s in 70s BMWs (a few '02 and a 2000CS IIRC, read over his stuff here). I'm sure he'd be willing to field a few questions for you - I've met him firsthand and he's a good guy.

[Matd]

Hi Dave,

thanks for the reply.
The COP conversion looks like a good idea.
Howerver I'd like to get the engine running first and afterwards start upgrading it.

Today I had some time to take the wiring harness out and try to find out what's what.
This is what I came up with (I hope you guys could help me fill in the gaps?):

Numbers:
1)  O2 Sensor
2)  4 coil connectors
3)  C101 connector
4)  Diagnostics connector
5)  ?? I guess battery ground (-)?
6)  Battery positive (+)
7)  Fuel pump, O2 heater and DME relays
8 )  ?
9)  ?
10) ?
11) ?
12) MAF connector
13) ?
14) Cranshaft or camshaft position sensor
15) Cranshaft or camshaft position sensor
16) Remote thermometer sensor
17) Coolant sensor
18) Oil pressure switch
19) ?
20) Fuel injector signals
21) DISA connector
22) ?
23) ?
24) ?
25) ?

I'm guessing number 22-25 are alternator/starter connectors.
Is the plastic connector containing the blue and thick red wire connected to alternator or starter?

I also tried to connect all the hoses.
Most of them are clear.
The ones below however I'm not sure of. Does the connection below look right to you?
Red circle: Disa unit
Purple circle: hose coming from intake bottom
Blue circle: Some kind of one way valve?

Also I don't know where the orange encircled should connect to... Any ideas?

[DesktopDave]

I can help you with a few of those questions, although I'm a little foggy on most of it.

I have an E30, but the harness is pretty similar between the cars. I'll check tomorrow. Keep in mind that BMW made all their grounds from brown wire, which becomes very difficult to tell from the red wires after a few decades. Dumb choice, but that's the way it is.

I believe the following to be true (but test it all with an ETM and a DMM):
#5 is a battery ground
#6 is clipped to the positive cable coming from the rear-mount battery. It's an insulated plastic block on the firewall unless you have a cabrio...those have a front mounted battery.
#8 is the firewall ground
#9 is the starter primary post
#10 could be the fuel vapor purge valve
#11 might be the oil pressure switch
#13 could be the AFM
#19 might be the knock sensors
Alternator stuff:
#22 alternator field wire
#23 alternator primary positive connection
#24 alternator wiring protector
#25 starter post or battery positive?

The blue circled-item is a one-way valve - it's the fuel tank purge valve. It has a wiring harness connector and connects to a vac line going to the manifold, and coming from the carbon canister. I didn't see one, probably isn't with your parts. No big deal.

[Matd]

Allright, thanks for the help.

I reassembled everything and tried to find out what everything connects to.
Most of them are clear however I'm not sure about the ones below:

Idle control valve and DISA connector: see images below. Can someone check on their car please?


Breather valve/ fuel purge valve: can someone check the picture below shows the right connection? It is on the same piece of cable that also contains the MAF connector and the 3 poled throttle position sensor connector.


Below it the disa assembly. I found a schematic of this and tried to connect it that way.
It still leaves me with the question of what the white valve connects to. I think it connects to the hose running from the intake (pruple in previous post) althoug I think dave thought this hose connected to the fuel tank breather valve/purge valve (I tried to connect these but the hose diamter does not seem to match).
Could someone check this on their car please?


This leaves me with 1 connector unconnected (2 poles and the longest cable). Could this be the reverse lights switch? Would make sense as it has to connect to the transmission so it needs a longer cable.

+ I have no idea what this hose connects to


Thanks for the time and your answers

[Matd]

I'm getting ready to try to start the engine by the end of this week.
Apart from the questions in the post above, could someone tell me if the diagram below is somewhat correct (especially the wire running from pin 22-->not sure if this is an input or an output). Also what Amp rating do I need on the ignition and start switches?
Thanks!

[Matd]

After looking at a lot of pictures on the internet I assume this hose connects to the brake servo booster (vacuum hose)?

[DesktopDave]

That definitely looks like a brake servo hose. It should also have a 90deg fitting that quarter-turns into the servo body, but that's missing.

[Matd]

Thanks for the confirmation dave
Any idea on the elctronics? I'd hate to fry my DME...

[Matd]

I got it started yesterday  !!
If someone wants to know how I connected it all:

X20 connector (E36!)
-Connect pin 13 to your fuel pump + terminal through a 15Amp fuse.
-Connect pin 21 to battery 12V+. You should hear he white main relay switch on. This powers up the DME.
-Connect pin 18 to 12V+ to engage the starter motor. The DME will notice you are cranking the engine and will also switch the fuel pump on. Disconnect from 12V once the engine runs of course.
I have not made any of the other connections but I'll do those later. Main thing for me was to be sure the engine was running before I invested in some new parts for it.

I did have a quite problematic fuel leak at the end of the injector rail where the fuel pressure regulator is mounted. Fuel seems to find it's way past the O ring seals once the fuel pump pressurezid the system.
Anyone else ever had this problem? Should I replace the whole fuel pressure regulator or just the O rings??

Thanks,
Mat

[DesktopDave]

Did you ever solve the pressure leak? I've been tempted to replace the o-rings with some viton rubber parts instead of the stock buna-n rubber, but the pressure regulators aren't that expensive. Be sure the rail isn't damaged by corrosion.

[Matd]

Hi Dave,

No I haven't replaced it yet. Project is on hold for the next 6 months.
I could not see any damage on the pressure regulator itself or the pressure rail so I think I'll try to replace the O rings first.