m30b35 swap e30, harness?

[willy-guldager]

So i need a new harness for my m30b35, and ive heard you can use a harness from a 325? Right now i have a harness from a 323i? Does anyone know if i can use that harness?

[E30_fiend]

Nope. It's needs to be a late model 325i harness. They are both Motronic 1.3 which is what you need.


Taylor

[tfritz]

I would personally use an m30b35 harness. Though it is said that the late model 325i harness will work, I had issues using that harness and went to the m30 harness with no problems.

[slammin.e28]

1987 325i harness works great, the ECU connector is correct, and the injector plugs aren't encased in a plastic housing.

Later 325i ones will work, but you'll have to take the injector plug housing apart.

I'd just get an M30B35 harness and be done with it. Everything will be proper and the injector wires will be in the housing as god intended.

[marshallnoise]

1987 325i harness works great, the ECU connector is correct, and the injector plugs aren't encased in a plastic housing.

Later 325i ones will work, but you'll have to take the injector plug housing apart.

I'd just get an M30B35 harness and be done with it. Everything will be proper and the injector wires will be in the housing as god intended.

+1

Not that I have a running b35 right now, but if you have to replace the harness anyway, might as well be the one the engine expects to use.

[E30_fiend]

The only way I would use the b35 harness is if the injector connections are changed to the tab style connectors. The b35 connectors are bullshit.


Taylor

[F34R]

I would personally use an m30b35 harness. Though it is said that the late model 325i harness will work, I had issues using that harness and went to the m30 harness with no problems.

I know a friend that used the b25 harness without any issues. It can be done, but the b35 harness is best if you have it.

[csermonet47]

I don't know why everyone keep saying the B35 harness is the best. The B25 harness is the best. Period. People that say otherwise do not know what they are talking about. There is no advantage to running a B35 harness and the engine doesn't "expect" a B35 harness, it expects a Motronic 1.3 harness. It could care less what car it goes to.

All it takes is little thinking and you make the B35 harness box work with the B25 harness. You literally have to lengthen 1 wire, removing some plastic, and rewrap the harness to make it work and it is 100% cleaner than using a B35 harness. It already fits the E30 engine bay and everything works like factory. No check engine lights or anything. C101 plugs right up and you're good to go.







Do what you want to do, but the M20 harness is without a doubt the cleanest way to do it.

[LJ851]

Do what you want to do, but the M20 harness is without a doubt the cleanest way to do it.

Sez Mr. Clean.

[E30_fiend]

I was waiting for Ryan to get in here.


Taylor

[Jb325is]

Yeah the b35 harness kind of fits terrible in the e30. e34 ecu's are in the engine bay, e30 is in the glove box, so the b35 harness is not long enough. I was trying to think of some reasons to go with the b35 harness while I was writing this but I couldn't.

[navytapaul]

I agree, I had to mount my ecu backwards just to get the harness to connect. Would have much rather gone with an i harness and the b35 plastics for aesthetics. Like it was said earlier, only 1.3 needs to be seen, harness doesn't really matter. I would rather have a harness that fits and doesn't have all the extra connectors my e32 harness has...

[G-Man the Visionary]

Did your B25 harness come with that TPS?
I've had my engine running (turned on/ idle) on the B25 harness (swapped TPS sensor), but didn't have a few plugs hooked up that wouldn't reach... While at the junk yard the other day, decided to grab a B35 harness... What mods would be necessary to run B35? I believe the C101 plug is the same, round...
Thanks

BTW, clean car... Hope to get there...

I don't know why everyone keep saying the B35 harness is the best. The B25 harness is the best. Period. People that say otherwise do not know what they are talking about. There is no advantage to running a B35 harness and the engine doesn't "expect" a B35 harness, it expects a Motronic 1.3 harness. It could care less what car it goes to.

All it takes is little thinking and you make the B35 harness box work with the B25 harness. You literally have to lengthen 1 wire, removing some plastic, and rewrap the harness to make it work and it is 100% cleaner than using a B35 harness. It already fits the E30 engine bay and everything works like factory. No check engine lights or anything. C101 plugs right up and you're good to go.


Do what you want to do, but the M20 harness is without a doubt the cleanest way to do it.

[lukeADE335i]

If you already have a M20 harness, then just unwrap it, plug all the plugs in on the engine and re-wrap it. Lengthen a couple of injector wires & fit the M20 injector loom into the M30 plastic box and you're done.

I did my swap this way & it is a lot neater than my friend's car who is running the M30 engine loom (for the reasons already mentioned).

[F34R]

Completely forgot the m20 harness is longer. I got lucky and did not have to cut any wires to run my b35. Came from factory all ready to fire and run perfect.