M30B35 Swap FAQ

[BuzzBomb]

What happened to your main relay and fuel pump relay?

He probably left the harness original from the e34 and tucked them under the carpet by the ECU. Not preferred, but the quick and dirty version.

[geordi]

This list should clear up just about every question of which parts you need, after using realoem and autohausaz for picture references, there should be no more excuses not to know which parts you need.

I wanted to track all the parts I need to either acquire, pull from my B34, or keep from the donor B35 so I took this MOST EXCELLENT post and turned it into a spreadsheet.

Hopefully this will help others. And hopefully this link to the web version of Excel works for you all.

Charlie's Excel version of Matt's Excellent List

Charlie, thanks for creating the excel list. I can't access it through the link. Can you send the spreadsheet to my email addy?
thanks

[tig]

What happened to your main relay and fuel pump relay?

He probably left the harness original from the e34 and tucked them under the carpet by the ECU. Not preferred, but the quick and dirty version.

What would be preferred?

[BuzzBomb]

What happened to your main relay and fuel pump relay?

He probably left the harness original from the e34 and tucked them under the carpet by the ECU. Not preferred, but the quick and dirty version.

What would be preferred?

If you can't source a harness from an '88-89 e24, the best looking install with an e34 harness is to lay it out, open the insulation, and re-route the power leads and relay sockets over to the opposite end with the C101 connection, then re-wrap it.

[Brad D.]

What happened to your main relay and fuel pump relay?

He probably left the harness original from the e34 and tucked them under the carpet by the ECU. Not preferred, but the quick and dirty version.

What would be preferred?

If you can't source a harness from an '88-89 e24, the best looking install with an e34 harness is to lay it out, open the insulation, and re-route the power leads and relay sockets over to the opposite end with the C101 connection, then re-wrap it.

Just make sure it's not an e34 EML harness.

[tig]

If you can't source a harness from an '88-89 e24, the best looking install with an e34 harness is to lay it out, open the insulation, and re-route the power leads and relay sockets over to the opposite end with the C101 connection, then re-wrap it.

My harness is from an E34.

I am likely going to re-route as you describe. I've already got it all unwrapped and I think I'd rather have the relays mounted somewhere secure, like the fuse box, than stuffed somewhere like in the glovebox. Thanks.

[autotech_ken]

We are breaking down our 92 735iL M30/B35 .

Have a few on another board looking for some of this to but just throwing it out there. Freshly pulled:
engine haness
MAF
Manifold
TB & TPS
Fuel rail and injectors
DME
Starter

loading up photobucket maybe later tonight
http://s1312.photobucket.com/user/Kens_ ... 20listings
Set it up with sub albums as we get it taken down will be loaded there and sold items moved off the albums.



Contact
awandrey@nc.rr.com

[danc]

ok, here's my small additions to this thread.

I ended up taking my B34 block and rebuilding it with a B35 crank/rods/pistons and head/intake manifold, etc... basically making a B35 out of a B34 block. im about 350 miles into break-in and so far im really happy with it.

Justin535turbo,

I've been reading up on this Swap FAQ, and your post above really got my attention (BTW, that's from May 2013, page 8 of the FAQ). I'm hoping you won't mind commenting. My 88 B34 is getting VERY tired, and I have the harness and ECU to do this swap. I also just picked up another 88, this time an "is". Looking forward to doing the swap on my older 535i, then maybe doing it in the future to the 535is, but I still need to find a good donor engine.

Anyway, did you get new internal parts to do this, or did you use the crank/rods/pistons from the donor motor? I've heard of people doing this, supposedly with some success, but the idea of putting used engine internals into a different block, especially one with high mileage, scares the crap out of me. It kind of goes against anything I've ever thought about engine rebuilds, but then again I learned on American muscle cars back in the day.
If this IS what you did, how has it worked out? I'd say you've had the motor in that state for almost a year, and that should give some indication. I was figuring on getting a new set of oversized pistons, rings, etc., but that's gonna cost. Not to mention the machine shop work.

Any other thoughts and/or opinions are, of course, welcome and encouraged!

BTW, yes, I've done some searching. It's a tough subject to search for, since I'm not sure what words to use. But here's one...
http://www.mye28.com/viewtopic.php?t=66880

[ZenitramNaes]

Can anyone answer the question about the 3 wire to 4 wire 02 wiring question that was posted in the first post? I'm unsure on how to wire my non OEM 02 sensor to the connector.

Am I right in assuming the following?

Grey-Ground
Black-Signal
White-Heater
White-Heater

[BuzzBomb]

Can anyone answer the question about the 3 wire to 4 wire 02 wiring question that was posted in the first post? I'm unsure on how to wire my non OEM 02 sensor to the connector.

Am I right in assuming the following?

Grey-Ground
Black-Signal
White-Heater
White-Heater

You cannot assume anything when it comes to wire colors in the O2 harness itself. The only way to know what wire goes where is knowing the pinout of the sensor in question, and comparing it to the pinouts of the injection schematics from a B35 car's ETM. Or just buy the correct O2 sensor and make it easy on yourself.

[ZenitramNaes]

Can anyone answer the question about the 3 wire to 4 wire 02 wiring question that was posted in the first post? I'm unsure on how to wire my non OEM 02 sensor to the connector.

Am I right in assuming the following?

Grey-Ground
Black-Signal
White-Heater
White-Heater

You cannot assume anything when it comes to wire colors in the O2 harness itself. The only way to know what wire goes where is knowing the pinout of the sensor in question, and comparing it to the pinouts of the injection schematics from a B35 car's ETM. Or just buy the correct O2 sensor and make it easy on yourself.

I'm pretty sure I got that info from a good source, can't remember now. I ended up just going and buying a replacement.

[muz]

This a great write up, so much knowledge shared its fantastic. Having said that though my head is spinning with information overload, too much for my old brain.

I have just purchased an e28 535i (m30b34) auto and the PO has cut a lot of the engine harness during the removal of the engine in preparation for a jap engine transplant.

I have the engine, transmission, tail shaft etc to put it back together.

So, my question to the group is do I either:

1) Find a replacement harness and leave it with motronic 1.0 and chip it
2) Upgrade to motronic 1.3 and leave it
3) Upgrade to motronic 1.3 and chip it

I'm not after HP but more torque and better driveability. Any opinion is appreciated.

[Heathcliffe]

Can anyone answer the question about the 3 wire to 4 wire 02 wiring question that was posted in the first post? I'm unsure on how to wire my non OEM 02 sensor to the connector.

Am I right in assuming the following?

Grey-Ground
Black-Signal
White-Heater
White-Heater

Here's a couple things that may help. I just put Motronic 1.3 in my E24 swap so i went from a 3 wire system- the original 1.0- to a 4 wire system. The Bosch O2 sensor I used had the wire config that you posted above so it was 4 wire plug and play. The Motronic 1.0 doesn't require the grey ground return wire to the ecu which the 1.3 does. That being said you might be able to either cap the grey wire or just ground it to something as the case of the O2 sensor is grounded in both 3 and 4 wire applications. Page 1360-8 of the 87 ETM shows the
Motronic 1.0 3 wire config and page 1360-6 of the 89 ETM shows the Motronic 1.3 4 wire config. Here's a link for wire color for various O2 sensor manufacturers http://www.google.com/imgres?imgurl=&im ... CAUQsCUoAQ . Or you could buy a 3 wire sensor

[BuzzBomb]

Can anyone answer the question about the 3 wire to 4 wire 02 wiring question that was posted in the first post? I'm unsure on how to wire my non OEM 02 sensor to the connector.

Am I right in assuming the following?

Grey-Ground
Black-Signal
White-Heater
White-Heater

Or you could buy a 4 wire sensor

Fixed, and that he did.

[DJM1986-5]

I'm adding the correct part number for the right side motor mount bracket when using a late model B35 block and the Koala Motor sports adapter bracket.... The bracket needed is pn 11811175592
it's used on 533s and still shows available new for about $22.

[captbly]

So does the oil pan hit even using that Kola Motorsports bracket?

[DJM1986-5]

The oil pan does not even come close. I believe it has more ground clearance than the B34 but I did not take measurements - just appears so. I used both Koala motorsport adapter plates with my old B34 bracket on the left and the 533 bracket on the right side - perfect fit plus plenty of room for the long-tube headers. I need to post a picture of this.

[DJM1986-5]

One more thing I discovered - from the 179 ecu wires #40 and #41 need to be tied together and attached to the AC "on" signal from the AC switch....

After studying the wiring diagram for the AC circuit I discovered that pin #4 of C103 (on the B34 side) carries a green and yellow wire that comes from the AC switch. Along with engine speed and fuel on pins #1 and #3, I attached wires 40 and 41 to pin #4, all using a spare C103 male plug I clipped from an old B34 wiring harness. (Make sure to get at least two or three inches of wire along with the male C103 plug so butt connections are easier.

[tig]

As an addendum to those using the e24 B35 harness, who also are more inclined to use this chart by color and not pin number, there are a few differences between the e34 harness wire colors and e24 harness.
#2 = BU/VI (same as e28)
#7 = large GN (same as e28)
#8 = small GN *This needs to be spliced into #7 above or you get no + to represent "key on" to the ECU, meaning no start.
#10 = BU/WT (same as e28)
And some of the unused wiring is different than the chart, but aren't necessary to note.
Since a lot of people are more visual and rely on colors in a schematic, it's good to know these differences.

I thought I had an E34 harness. I was stumped as to why #2 was BU/VI according to my multimeter and not GN/YL as the chart shows. Now I know I actually bought an E24 harness. Thanks!

[tig]

One more thing I discovered - from the 179 ecu wires #40 and #41 need to be tied together and attached to the AC "on" signal from the AC switch....

After studying the wiring diagram for the AC circuit I discovered that pin #4 of C103 (on the B34 side) carries a green and yellow wire that comes from the AC switch. Along with engine speed and fuel on pins #1 and #3, I attached wires 40 and 41 to pin #4, all using a spare C103 male plug I clipped from an old B34 wiring harness. (Make sure to get at least two or three inches of wire along with the male C103 plug so butt connections are easier.

Thanks. Good info; glad I saw it. Some more info to further clarify with pics:

Here's C103 under dash.


Here's C103 on a B34 harness.


Page 6411-0 of the ETM shows pin 4 of C103 as GN/YL "Not used".

I had a spare E28 harness and pulled the male C103 off of it. I then pulled the male of this, whatever it is, and broke the male part apart to extract the pin out from inside it.


I used that pin to add a pin to #4 on the C103:

[tig]

I've read and re-read this thread regarding the coolant temp sensor/coolant temp sender. I got totally confused and had to step back to make sure I really understood. Hopefully this will help others.

The B35 has two coolant temp thingies that are plugged into the thermostat housing.

Coolant Temp Sensor
This puppy feeds the ECU with info on the engine temp. It connects with two wires via a BLUE connector (at least on my E24 B35 harness). The wires that run to it are BR/RT and BR/OR. The BR/RT goes to pin 45 of the DME. BR/OR is ground.


Coolant Temp Sender
This goes to the instrument cluster and drives the temperature gauge. It connects with two wires via a BLACK connector. The wires that run to it are BR/VI and BR/GE (GE is yellow). On an E34 both wires go to the the cluster. It appears BR/GE is power and BR/VI is the sender.


The B34 has three thingies plugged into the thermostat housing: A Coolant Temp Sensor, Sender, and the Thermotime Swtich. The Thermotime Switch is not needed on the B35.

The B34 Sender has one wire (the B35 has two per above).


The E28 cluster has a BR/VI wire leading to it that feeds the temperature gauge. If you are using a B34 Sender, then the BR/VI wire from the harness (was going to pin 4 on the 20X connector) will go to the BR/WH wire at pin 4 of the C101.

This is super straight forward, so I'm not sure why others had temp gauges that didn't work. Maybe it's because they were using B35 Senders?

[tig]

I have a question about pin 14 of the 20X. BK/WH (SW/WS) wire that goes to the ECU "Speed Signal Input". I believe this is Pin 29 on the ECU. The E34 ETM shows the cluster as having a "Vehicle Speed Output" that goes to Pin 29 of the ECU.

In the wiring chart above, there's no E28 connection for this. Am I correct in my understanding that on an E34/E24 etc... this is an input INTO the ECU from the speedometer and that ECU does something with this...and that this is not really needed (hence no angst over not connecting it on an E28)?

Mostly just curious.

[tig]

I'm really struggling to figure out how to wire in my harness. My problem is that I am un-willing to just blindly splice things together when either the colors or pin #s in the previous posts are ambiguous. I need to understand what goes where.

My 20X connector/harness does not seem to map up to all of the mappings above and I've taken to my multimeter to try to figure out what's going on.

My B35 harness, has these connectors near the ECU plug. I figured out what they are all for.



From Left to Right:

White 4 pin - X79 - This is for the ABS pump; not necessary on E28s, but you'll want to use two of the leads...
R (12V)
BK/GN (From Starter; I think this goes hot when "Starting")
BK/GR (ECU - Pin 40 - AC Low Pressure Cutoff)
BK/BL (ECU - Pin 41 - A/C On input - ETM says "Aux Fan")

You'll want to tie both the BK/GR and BK/BL to the #4 pin on the C103.

Black 4 pin - X1552 - This is for the "ebox cooling fan" - You can ignore it for E28 installations.
NC,
BR/GN (To BR/GN Oil Press Switch)
GN/WH (Connected to pin 6 on 20X connector)
BR (Ground)

You can just ignore this connector

Black 8 pin - Not needed, but has some useful stuff on it
Yellow - to TPS
Red - ECU Pin 36 - 12V Main Relay Output
Red/Blue - Switched 12V from Main Relay 87a
Brown/White - ECU Pin 51 - Auto kickdown switch input
Black - to TPS
Brown - to TPS
Brown/Green - ECU Pin 3 - Fuel Pump Relay Control


Black 2 pin - ??? Probably not needed - I think this connects to the AC switch on an E34/E32???

[demetk]

CEK, I don't think you need any of those harness connectors for your install. Let me take a look at what I've done under the dash and post a pic, but I'm pretty sure I just took two wires from c103 and spliced them to the appropriate pins on the ecu connector as was described in the faq.

What year/model e34 harness do you have?

[tig]

What year/model e34 harness do you have?

I'm not sure. Seller told me it was from an E34.

Appreciate you taking a look! I'm sure I could just ignore all that stuff and splice in the C103 wires for 40 & 41, but I HATE not understanding the details.