The comprehensive DOHC engine swap thread.

[tranceguy]

The green wire runs from the DME to the C101 plug. On the E36 side, there is one large green (power to coil packs) wire and 2 small (~16 gauge) wires that splice into it about 3-5 inches before C101. I think one was for an immobilizer, but the other one is an ignition power for the DME. I'll check which pin on the DME plug it is.

Check to see that you're getting power to the large green wire when the ignition is switched on. Also check to see that the all red wires on the main relays are getting power all the time. Also look for a ground on the relays.

[rs4pro3]

Yep Like e9ine said Check the starter wires, Some of the e30's have 3 wires going to the starter, so the c101 will have an extra pin you'll have to add. I had the same problem with the m30 swap, the windows wouldn't work so I had to add a pin and wire it to the Black yellow wire coming off the starter. The unloader relay is the problem as it's grounded threw the starter.

[Addissimo]

The starter wires are good. I checked all of the wires on the relays, they were all good except for one of the grounds. I couldnt get any response from my multimeter. I think it was going to the blue relay and it was a green/brown wire. Tomorrow i'll slice open the shielding on the harness and look for those green wires. I'm beginning to wonder if it wouldnt just be better to get an e36 harness and hook it up. I might take it to the local shop too. They have done a few m50 swaps, and might know whats up right away. I dont think they have actually done any with the stock ecu, seems like all of theirs are turbo monsters... but i guess i'll give them a shot. I'm still open to suggestions for sure though.

thanks,
-Addis

[325Projectz]

Well look at it this way, If you take it to a shop how much are they going to charge you per hour, 60, 70, $80? Shit, it might take them hours to find out whats wrong, so if you are sure it is somewhere in the wiring harness, then you could save money and try to find another one, or keep diggin in yours to find out whats wrong, just have a ohm meter and a test light handy. I got mine for I think $120 shipped w/ fuel rail and injectors.

I had a huge problem with my harness, also. I had power wire that was so faded and dirty, lol, it looked like a ground, but it wasn't. It took about 2 hours on a test light to find out exactly what the problem was. Does any part of your harness have power?

Oh, and I went to the track tonight to drag the car, 15.3 in the 1/4 . I'm not to happy about it, although it was better than my 16.4 m20. I spun the tires through first, half way through second, long cherp in to third and a tiny cherp into fourth. I never knew how much attention the e30 m50 would get, alot :D , still needs a turbo :twisted:.

Speaking of which, when I was down there a kid approached me and asked what I had done to it, and we got to talkin. Come to find out (unverified, don't quote me :roll: ) he has a 84 318 with a twin turbo'd 99 s52 :shock:. I was like daaaamn, that sick! But I don't know for sure, but he seemed to know alot about the cars. Anyway, just thought I'd like you guys know.

[Jason89i]

Yep Like e9ine said Check the starter wires, Some of the e30's have 3 wires going to the starter, so the c101 will have an extra pin you'll have to add. I had the same problem with the m30 swap, the windows wouldn't work so I had to add a pin and wire it to the Black yellow wire coming off the starter. The unloader relay is the problem as it's grounded threw the starter.

i had the same problem. no p/w and blower motor. it was the k5/k7 relay wire.....the body electronic controls. lets see here. at c101 the black/green wire (e36 pin 15) should be spliced to the black/green wire (e30 pin 15.) on some e30's the black/green wire comes off the small terminal of the starter. on my car i ran the black/green (e30 pin 15) to the starter terminal. but ive also done the pin15 to pin15 and both methods work.

rs4pro3 and e9ine are right on. my first conversion i missed that wire and i had the exact same symptoms. no windows, no heater blower.

[Addissimo]

yeah... my friend alfie has a twin turbo s52 in his 88 325i. It was for sale a while back on this forum, but he decided to keep it. He got an m3 with light front end damage and is putting everything in that. I havent ridden in his 325, but i think its a 10second car after he fixed the clutch problem. damn fast.

I'm going to fuck around a bit more today with everything. If i cant get it to work, I'll buy a new harness, i think i'd like to go that route anyway because the e34 harness is too short and barely fits in the car.

thanks for everybody's help
-Addis

[sschin]

My friend just flippped over his '93 E34 525i automatic

I'm going to pull the motor and put in to my car. I'm getting the motor at a good price.
'89 325i manual

I have some questions:

1. What other stuff do i need from that car besides the engine, wiring harness, a/c and what else? Fuse box? or do i use my '89 one? Relays?

2. The ECU is from an automatic car so do I need to get a different ECU?

3. The MAF sensor has oil all over it from the car flipping over. Can I just spray some Brake cleaner on it or do I need to get another one?

4. What shifter linkage should I be using with my stock M20 tranny?
I just rebuilt mine less than a year ago and have a z3 1.9 shift lever in there.
E36 shift linkage?

5. Someone said the wiring diagram on that link on previous page was wrong or something. so what is the right or correct way of wiring the car up to my car?

6. Do I use the M50 a/c or can i just use my M20 a/c... My a/c is still very good.

7. The speed reference pin.. where do i get one and wahts the part number?
where is that little wire that plugs into it come from?

I'm totally new about putting a newer engine into my E30. So please help and be nice. hahaha

[Brew]

My friend just flippped over his '93 E34 525i automatic

I'm going to pull the motor and put in to my car. I'm getting the motor at a good price.
'89 325i manual

I have some questions:

1. What other stuff do i need from that car besides the engine, wiring harness, a/c and what else? Fuse box? or do i use my '89 one? Relays?

Stock fuse box. The three main relays are part of the engine harness, so the old ones will come out with the m20 and the new will go in with the m50.

2. The ECU is from an automatic car so do I need to get a different ECU?

Good question. I think so, but I'm sure someone else can tell you better.

3. The MAF sensor has oil all over it from the car flipping over. Can I just spray some Brake cleaner on it or do I need to get another one?

It may be still good, but there is an easy test that you can do once you've got the motor up and running.

4. What shifter linkage should I be using with my stock M20 tranny?
I just rebuilt mine less than a year ago and have a z3 1.9 shift lever in there.
E36 shift linkage?

Stock linkage, although you may want to bend either the selector rod or the shifter itself, as the tranny is going to be tilted to the right.

5. Someone said the wiring diagram on that link on previous page was wrong or something. so what is the right or correct way of wiring the car up to my car?

All of the info you need is in this thread. Because you have a late model, you will need to do additional wiring for the unloader relays.

6. Do I use the M50 a/c or can i just use my M20 a/c... My a/c is still very good.

M50 compressor, although I think you may need custom AC lines. Im sure others can tell you more about this, as I chose to remove the AC on my car.

7. The speed reference pin.. where do i get one and wahts the part number?
where is that little wire that plugs into it come from?

I think the wiring is in this thread. It is a straight-splice right at C101.

I'm totally new about putting a newer engine into my E30. So please help and be nice. hahaha

[sschin]

Thanks Brew for the response.

I'll have more questions once its time to put that motor in like a couple of weeks down the line.
Thanks,
sschin

[Bryson]

for the AC .. you need custom lines, you can use the high pressure (IIRC) line from a '91 318is, the other has to be custom
compressor from any m50 variant car. Mind you it's a tight fit in an e30 with the exhaust manifold and coolant hose

edit: e34 automatic has a separate wiring harness, so you will be fine

[Bryson]

Re: Wiring Questions

If you get your car to start, I'll hate you... Then i'll ask you how you did it. I havent had luck with getting mine to start yet. :?

-Addis

come to San Diego, we'll get yours started. sorry, had to :D
We're on #6 this weekend and possibly the harness for #7
All have been successful, knock on wood.

[Addissimo]

hahaha

Yeah, i'm definately a newbie to this shit... I would be more willing to get out there and figure everything out if it werent 30 degrees outside. Fuck idaho.

Anyway, I have decided to go with megasquirt and add a whole other headache to my car :) yay... I probably wouldnt do this, but I want to turbocharge this summer, and I figure in the long run it'll be easier and cheaper, and after a run or two on the dyno, i'll be getting maximum power from my engine.

I could just be crazy though :shock:

-Addis

Edit: come to think of it though: If anybody has a harness that they are absolutly sure it works they'd like to sell, It'd be nice to make sure my engine works before I start tearing shit appart to megasquirt my car. PM me.

[grapedrink]

M50 Guys


Bad news for me. I have completly rebuild the bottom end of my engine (92) and just started on the head and found cracks. It explains why the car would over heat alot. Anyway I have a complete 93 vanos engine also and am wondering if I take out the camshafts and use the 92s will the head work for my 92 block?

Lucas

[Addissimo]

I know you can take a 92 head and retrofit vanos into it to use it on a 93 block... so I dont see why you couldnt go the other way. You would be putting the dual valve springs from the 92 head on the 93 head right?

-Addis

[grapedrink]

Yea I will have the duel valve springs. I figured I could swap between them I just need to keep the internal stuff non vanos.