M30B35 Swap FAQ

[Justin535turbo]

this thread is very helpful when doing this swap. I put about 200 miles on my car this weekend, 200 down, 1800 to go to complete break-in! it runs soo much smoother than the old B34 did. also, my "indicated" fuel economy went from about 23 to over 26. 23 used to really mean about 19 - 20, so im assuming 26 really means about 22 - 23. which isn't too bad! i'll take the increase in power, smother run, and better fuel economy any day! i will also post some pictures of some obstacles that i ran into not covered in great detail here.

[Brad D.]

this thread is very helpful when doing this swap. I put about 200 miles on my car this weekend, 200 down, 1800 to go to complete break-in! it runs soo much smoother than the old B34 did. also, my "indicated" fuel economy went from about 23 to over 26. 23 used to really mean about 19 - 20, so im assuming 26 really means about 22 - 23. which isn't too bad! i'll take the increase in power, smother run, and better fuel economy any day! i will also post some pictures of some obstacles that i ran into not covered in great detail here.

Good to hear! Make sure you post up the pics of your issues and how you solved the issue.

[tig]

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

[Justin535turbo]

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

first off, the purge valve line. this line goes up to the intake boot on a B34. you need to run it over to the canister purge valve on the B35 which is on the other side of the engine under the intake manifold, i just used some plastic hose barb style connections and some fuel line. it only has fuel vapors go through it, no pressure at all. this is where i connected it.


#1 is where i connected the line, #2 and #3 is just showing the route across the bulkhead, #4 is the connection at the purge valve.


next is the ignition coil and wiring. #1 and #2 are grounds that come off of the B35 harness, i grounded them to the strut tower. #3 shows how i mounted the ignition coil. all i did was use adel clamps and went around the a/c lines right there, then sent bolts through the mounting holes on the coil. i wasn't sure how this would work, but its surprisingly solid and seems to work well. also keeps it far enough away from the exhaust so that it doesn't get too hot. #4 just shows the harness connection at the coil. I didn't have to modify the harness at all for where these are mounted/routed. you can of course modify the harness to reach down to where the factory coil mounts as well, but i thought i'd try this first. the other two unlabelled arrows just show the canister purge line mentioned above.


shot of the harness going through the bulkhead.


i took the 20 pin and engine/chassis harness connector bracket from an E32 and modified it to fit right here next to the expansion tank. #1 is the bracket. #2 is the 20 pin diagnostic connector. #3 is the engine harness to body harness connector that goes to the E28 C101 connector. #4 is the E28 C101 connector.


#1 is my modification to the expansion tank bracket to make room for the bracket/connectors. I had to move it over about an inch and a half. #2 is the canister purge valve, again mentioned earlier.


this is the intake i had to fab up. I still need to make a heat shield though.

I also was unable to get the B35 coolant temperature sender to work correctly. i swapped the wires as mentioned elsewhere, but it didn't work for me. so i just used the B34 temp sender. it has 2 wires coming off or it, and the B35 harness has 2 wires also. there is no polarity to these, just connect them both to the two wires in the B35 harness. 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.

[Brad D.]

I recall having the same issue with the b35 CTS for the gauge. IIRC, the wires in the connector have to be de-pinned and swapped in the plug.

[BuzzBomb]

Edit: Solved

[BuzzBomb]

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.

[kzolee]

I have replaced the fuel lines, but sometimes there was slight smell of gasoline in the engine bay.

I forgot one little piece



This is very underhand leak, because the fuel is dropping at the top of intake manifold, and evaporates on hot surface very fast.

[Justin535turbo]

I finally got around to finishing my intake for the car. I've got about $100 in materials into this one. It took much more fab work that I thought it would, mostly due to the heat shield. I'd recommend just buying the one for $225 from TCD. Which I swear I have seen on his website before, but now i can't find it...? I'm not normally a huge fan of cold air intakes, but the B35 AFM position made it an easy option. It makes a little more intake noise than normal. But im sure performance is negligible.

[viprojekt]

Hey all, I know I'm probably asking a stupid question here, but I have read through this thread a few hundred times, and I just wanted to double check before investing in the swap, are B32 and B34 motor mounts, harnesses and overall swap to B35 fairly equal? I have a '83 533i, and this thread seems to be all for B34. I'm new to wrenching on cars and I look forward to getting into working on my car! Thanks for any help.

Sean

[My528e.awesome]

I was told the b32 does very well with just the Motronic 1.3 swap. Someone correct me if I'm wrong.

[gmb49all]

I would recommend you start with the 1.3 swap first. If you dox it, and you find you still want more, than upgrade to the B35 - at least you'd have all the engine management stuff already in place.

A lot less work at first, and it sets you up nice for a b35 upgrade if you feel you want to try it....

[BuzzBomb]

Hey all, I know I'm probably asking a stupid question here, but I have read through this thread a few hundred times, and I just wanted to double check before investing in the swap, are B32 and B34 motor mounts, harnesses and overall swap to B35 fairly equal? I have a '83 533i, and this thread seems to be all for B34. I'm new to wrenching on cars and I look forward to getting into working on my car! Thanks for any help.

Sean

it looks like all you'll have to do it fabricate the adapters for the mounts like others have shown on this thread. Besides that, no worries.

[9mil]

Read through the thread and still can't wrap my head around my dash temp sensor not working. I have tried a couple of gauge sets none seem to work correctly at all- I have another one coming to make sure it isn't my old junk / si board issues.
Using MS so I can see the temp on my TS dash so at least I'm not totally screwed - but this brings up my point.
I have an e32 179 harness and I only have one temp sender connection and it connects fine- I haven't cut anything to adapt it to the m106/b34 gauge sender unit. I get CT (appearntly) from this connection so I am hesitant to butcher it and redirect the signal to my dash.

Anyone messed with this? I am having some tach issues too- so I'm not all convinced it isn't the gauges.... But I don't see how they can be connected to both (without yet another wire bypassing my goathumper apadpter board and butcher the plug to go to the b34 sender)
Did that make sense?

1987 e24 5spd - m106 turbo with FMIC with later model e32 motronic 179 harness with BIMMER guy c101 plug and goathumper adapter board to MS1

Thanks!

[BuzzBomb]

bummer guy c101 plug

I just gotta assume that this is a typo and you're not being disrespectful.

[9mil]

Absoulutly a typo. Posting from phone.
He has been great - no disrespect at all... Ill edit.

[9mil]

Got the alligator clips and leads out and did some playing around.
Temp gauge will work with b34 temp sends grounded on one spade and the other to the #4 pin in the c101.... Leave the one in the b35 harness alone, feeding the MS...

Just incase some other poor bastard is searching

[anton-sa]

hi there
would you guys say its feasable and/or do-able to
buy a e34 535 in manual form with lsd. and swap the entire lot over into my 86 520i ?

e28's are so so scarce, especially in my country (south africa) where we only got them from late 85 to 89. we had the e12/8 here till late 85. which is basically a e12 chassis with e28 bits.

anyhow, to get my "foot in the proverbial e28 door" i had to settle for a neat/clean/straight 520i 86

[kzolee]

You can swap the engine and transmission, but you will need a driveshaft, custom engine mounts.

The diff internals are interchangeable with the 520i.

The output shafts on the 20i are weak for M30 power. You will need the bigger output shafts, the rear drive flange from an E24 or E28 525/28/35i.

[tig]

i took the 20 pin and engine/chassis harness connector bracket from an E32 and modified it to fit right here next to the expansion tank. #1 is the bracket. #2 is the 20 pin diagnostic connector. #3 is the engine harness to body harness connector that goes to the E28 C101 connector. #4 is the E28 C101 connector.


#1 is my modification to the expansion tank bracket to make room for the bracket/connectors. I had to move it over about an inch and a half. #2 is the canister purge valve, again mentioned earlier.

What happened to your main relay and fuel pump relay?

[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.