M30B35 Swap FAQ

[tig]

FWIW, this link has been super useful to me in ensuring I'm doing things right...

http://www.e30zone.net/e30zonewiki/inde ... tronic_1.3

[demetk]

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.

So I did not use those connectors on the e28. In fact, for my M1.3 install, I completely cut them off and taped the wires into the harness for a cleaner look.

Here's some pics of where they connect to my 89 e34.





On the e28, these are the only two c103 connections I did directly to the ecu harness as described in this faq.



Main relays and fused main power feed wire I mounted here.

[tig]

Demetk = hero.

[tig]

Buttoning up the harness and a few things have me stumped.

First is the green wire that comes off #86 on the main relay. It's not going anywhere now.

I think it's supposed to go to the C103:


Here's what it looks like inside the car:


The C103 pins
1 - Black - Goes to Tach. Comes from Pin 6 on ECU (B35).
2 - Green - Goes to OBC Relay Box (pin 4). Comes from ???.
3 - White - Goes to economy meter. Comes from pin 32 on ECU (B35).
4 - Green/Yellow - Goes to AC Switch (sort of). Not connected on B34. Comes from Pin 40/41 on ECU on B35.

On my B34 pulled out of Vlad it does.

However, in all the instructions above regarding C103 people say "Just hook up pins 1 & 3".

This doesn't seem right. Can someone confirm that this is supposed to be hooked up for a B35.

[tig]

While you guys are helping with the C103 above, let's talk O2 Sensors and O2 Sensor Relays.

The outputs from my O2 Sensor Heater Relay, seen here just off the eraser of the pencil aren't connected anywhere yet.


The Green/Brown wire coming of of #85 of the O2 Sensor Heater Relay is not connected to anything.

According to the E28 ETM, these relay connections are:
30 - Green/Blue - Goes to O2 Sensor Heater (white)
85 - Green/Brown - Goes to ECU Pin 31 (O2 Sensor Heater Control)

On the E34/B35:
ECU Pin 10 is O2 Sensor Ground
ECU Pin 23 is O2 Sensor Heater Control
ECU Pin 28 is O2 Sensor Input

The O2 Sensor Connector (on the engine) has the following leads:
1 - Yellow - Sensor Ground - To ECU Pin 10
2 - White - Sensor Input - To ECU Pin 28
3 - Ground
4 - Green/Violet - Heat - (From 87 on Relay)

This is all fine and dandy, however, my ECU connector has NO CONNECTION at Pin 23. I have two B35 harnesses. There is no connector on Pin 23 of either of them!??



Where do I wire the input (#85) of the O2 Heater Control Relay from?!?

[demetk]

Are you sure that is pin 23?

[tig]

Are you sure that is pin 23?

Pretty sure.


http://www.e30zone.net/e30zonewiki/inde ... tronic_1.3

[demetk]

Are you sure that is pin 23?

Pretty sure.


http://www.e30zone.net/e30zonewiki/inde ... tronic_1.3

Is that pin numbering for the wiring face or the mating face?

[tig]

Are you sure that is pin 23?

Pretty sure.


http://www.e30zone.net/e30zonewiki/inde ... tronic_1.3

Is that pin numbering for the wiring face or the mating face?

Mating face. Although it wouldn't make any difference. Pin 1 is farthest away from wire bundle and on the longer row. Can't screw that up.

[demetk]

So that looks be a mistake in the ETM. Mine doesn't have a pin at 23 either but my o2 sensor relay works. How many brown/green wires at the harness ecu connector? I wonder if they spliced 3 & 23 together and didn't update the schematic. I'll bet there's only one trigger for both the o2 relay and the fuel pump relay and it happens at pin 3.

[tig]

So that looks be a mistake in the ETM. Mine doesn't have a pin at 23 either but my o2 sensor relay works. How many brown/green wires at the harness ecu connector? I wonder if they spliced 3 & 23 together and didn't update the schematic. I'll bet there's only one trigger for both the o2 relay and the fuel pump relay and it happens at pin 3.

I just downloaded the 1991, 1992, and 1993 E34 ETMs just to see if an updated ETM (over 1990) would be different.

All of these ETMs include a nice ECU pin-out that show Pin 23 as "Not Used".

In addition in 1991-93 the O2 Sensor Heater is fed by #87 on the Fuel Pump Relay. Interestingly, the Fuel Pump Relay input is hot always/not fused. This means that on E34s the O2 Sensor Heater is not fused either! Odd, but BMW knows best.

So, there you go. Not only is the 1990 ETM wrong, but the ECU documentation on E30 Zone is wrong. And Demet is right.

It turns out I had mistakenly connected the output (87 Green/Violet) of the fuel pump relay to the line that feeds the o2 sensor heater in the o2 sensor connector. This would have worked fine, and I could have removed the Heater Relay, but not having it fused was bugging me. I also didn't like the fact that I had done this by accident.

Now pin 3 of the ECU now will close both the Fuel Pump and O2 Heater Relay.



The net of this is the E28 O2 Heater Relay is completely superfluous when moving to a B35! Pin 6 of C101 does not actually need to be connected to anything (other than the diagnostics connector, if you really care). Or you can do it the way I did.

[danc]

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.



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???

You may have just answered the question (the one that no one is really asking) regarding how to incorporate an auto trans into the conversion.
I'm going to have to take a look at both ETMs (E28 & E34) and see if I can make sense of those TPS connections.

[tig]

A note on dipsticks:

I was using a red one in my M30B35. The handle broke today which made me check the 2 others I have; that's when I noticed they were different and I dug in to find out what was right. I didn't realize they were different lengths.

According to RealOEM the E28/M30B34 dipstick tube and the 89/E32/M30B35 tube are both 300mm.

The M30B34 dipstick is part #11431266740 and according to RealOEM should be 552mm.

The M30B35 dipstick is is part #11431718861. RealOEM does not specify a length, but does show it with a metal loop handle.

I measured the dipsticks I have and...

The two red dipsticks below have an overall length of 545mm. The metal part is 450mm. (They look different because of the camera angle; they are the same length).

The yellow dispstick has an overall length of 550mm. The metal part is 400mm.



The B35 oil pan is shallower than the B34 pan. Both blocks have the same length tube (300mm). I verified this by measuring the tubes on my B35 block and 2 B34 blocks. They are the same length; about 260mm meaning about 40mm is inserted into the block.

If you use a B35 oil pan you should be using part #11431718861.

[tig]

Why would I want a “B35” in my car?

Additionally, fuel economy should improve as well.

I averaged 36.7 mpg from Portland to Seattle yesterday. According to my OBC. My econometer seemed generous too; always wanting to be further to the left than I would expect.

IOW, something ain't right.

I've searched and found no one else complaining of their econometer/OBC read wrong after a swap. Maybe I just did a REALLY good job on this engine build? Haha.

Could be:

- I missed something in the swap instructions?
- I'm using 24lbs injectors and that's confusing it?
- Something else?

I sure would like my OBC/ecometer to be at least somewhat accurate. Whelp.

[Kyle in NO]

It's the 24lb injectors.

[tig]

It's the 24lb injectors.

Ok. Thanks. Now what?

[Kyle in NO]

I dunno. Jump back to 1987 and recalibrate the programming for the OBC I guess.

I just live with mine, as the Econometer and OBC mileage calcs serve no useful purpose for me.

[Jeremy]

It's the 24lb injectors.

Ok. Thanks. Now what?

24 lb injectors use a shorter pulse width to deliver cruise fueling than stock. The dash econometer and OBC functions are both based off injector pulse width, so they think you're using less fuel. Search the archives, I remember somebody mentioning an adjustable pot on (I think) the OBC that could be used to adjust the calculation for larger injectors. Bit of a guess and check process so it's a PITA, but if it's important to you that it works correctly you could try it. The econometer on the dash is a lost cause though I think.

[e27moloko]

Hey guys Im over in Adelaide SA Australia and was wondering if there is any one on my e28.com that could help me with this conversion?
I recently bought an e28 535is m-tech with what i believe to be the M30B35 engine all ready bolted in my problem is the wiring has been spliced and is looking on the bad side, poorly done.
The person I purchased the car from for very little said that it was running before i bought it but very ruff. The starter motor is not wired in so Im unable to start it.
just wondering if any of the people on this forum would be able to help or know of someone that could in SA..
Thanks in Advance Justin

[e27moloko]

hey guys id also like to know if you can make a 1989 535i e34 automatic harness work with a manual 1986 e28 535i m30b35 engine????

[mitch5]

hey guys id also like to know if you can make a 1989 535i e34 automatic harness work with a manual 1986 e28 535i m30b35 engine????

Yes you although you do have to change a few sensors, first one of the top of my head is the tps sensor. A lot of people prefer the e34 Barnes because its has the plastic cover for the injector wiring

[e27moloko]

Yes you although you do have to change a few sensors, first one of the top of my head is the tps sensor. A lot of people prefer the e34 Barnes because its has the plastic cover for the injector wiring

Thank you mate much appreciated i will now be able to buy the harness from a e34 535

[John project car]

Anyone know if a wiring harness out of a e32 will work ? I happen to have one for parts with a good engine - drives , no interior . Want to do a turbo on mine and I am thinking I might as well swap engines too,

[kzolee]

Yes, the E32 harness works. My car has also an E32 harness.

[tig]

If you are putting an M30B35 in an E28, you might want an intake manifold bracket that will fit. See this thread:

http://www.mye28.com/viewtopic.php?f=4&t=126900