Bare minimum wiring for the M30 engine to run properly

[tinytim]

I am trying to track down a wiring diagram or at least information on the bare minimum wiring that is required to make the m30 run properly. I've found bit of information but but no definitive answer. The vehicles main purpose will be for autocross and road racing. I will not be using the stock cluster, I don't care about the info center working either. I will be building a harness for after market gauges from scratch.

Has anyone seen a wiring diagram and/or a detailed write up on this. Read it can be run properly on only 7 wires.

[RonW]

I am trying to track down a wiring diagram or at least information on the bare minimum wiring that is required to make the m30 run properly. I've found bit of information but but no definitive answer. The vehicles main purpose will be for autocross and road racing. I will not be using the stock cluster, I don't care about the info center working either. I will be building a harness for after market gauges from scratch.

Has anyone seen a wiring diagram and/or a detailed write up on this. Read it can be run properly on only 7 wires.

Get an ETM for the car the engine came out of. Remember, the M30 first went on sale in the late '60s, and was not injected at the time. For an E28 535i, you have to connect up the ECU, because it controls the ignition timing and the injectors.
Bare minimum as I see it, for the 535i:
ECU pin 1: Goes to pin 1 of ignition coil. You need this.
ECU pin 2: Closed throttle input. If you don't care for a rock steady idle (and if you have an E28 535i, you don't) don't bother connecting this.
ECU pin 3: WOT. Your preference whether you connect this. You don't actually need it. I think it never worked on my car, and I've owned it for 20 years. Then again I get 27 mpg, so I've probably never actually been at WOT.
ECU pin 4: Goes to starter voltage, so the ECU knows the car is being started. You can probably ground this wire instead.
ECU pin 5: Shield for reference point input. Also ground. Maybe you don't actually need it.
ECU pins 6, 7, 9, 22: AFM. You need these.
ECU pins 8 & 27: Engine speed sensor. You need these. They're a shielded pair.
ECU pins 10, 16, 17, 19: Ground them all.
ECU pin 11: Fuel rate output. This is for you econometer. Skip it.
ECU pin 12: Goes to diagnostic connector. Skip it.
ECU pin 13: Goes to engine temperature sensor. You might be able to wire this across a fixed resister, but the engine won't run well at all if you just leave it floating.
ECU pins 14 & 15: Fuel injector control. These signals are connected together inside the ECU, but you should probably use both as intended to handle the current. Each one goes to three injectors.
ECU pin 18: 12V at all times. This is so the ECU doesn't have to recalibrate itself every time it starts up. On the 535i, this wire isn't even fused - it goes straight to the battery. I'd skip it for autocross.
ECU pin 20: Fuel pump relay control. The ECU grounds this output to run the fuel pumps. If the engine stalls, the ECU shuts off the relay. This is good, but if you want to take a chance, you can leave this disconnected and ground the relay at all times. It won't turn on the pumps unless the ignition is on anyway, but if the ignition is on but the engine is off, those pumps will be on, even if there's a fire. Your call.
ECU pin 21: Engine speed output. Goes to your tach. You don't actually need it to run the engine.
ECU pin 23: Shield for engine speed sensor. A good idea, but you don't actually need it.
ECU pin 24: O2 sensor input. You can probably skip this.
ECU pins 25 & 26: Reference point input. You need these. They're a shielded pair.
ECU pin 28: Input from auto transmission. Ground it.
ECU pin 29: A/C compressor on input. Ground it if (and only if) you aren't connecting it to the compressor.
ECU pin 30: Don't know.
ECU pin 31: O2 sensor heater control. If you're skipping the O2 sensor, skip this too.
ECU pin 32: Don't know.
ECU pins 33 & 34: Idle speed control. Skip 'em.
ECU pin 35: Power when the ignition is on. You need this.

In addition to all these, you need to run ignition power to the high side of all the injectors, the fuel pump relay coil and the ignition coil.

That's a lot more than 7 wires.

[demetk]

Vote sticky.

[Mike W.]

Bare minimum? Well, it would be a lot less if you're running carbs and a conventional distributor. If you're talking Motronic, you would need the stock Motronic harness, but could do with less on the engine harness side coming out of the fusebox.

[tinytim]

Hell yeah Ron! That's what I am talking about!

Would this guide work with the diagrams in the bently manual?
Its the original engine in the car (87 535i).

I kinda had a feeling that seven wires what a bit of a stretch.

[RonW]

Hell yeah Ron! That's what I am talking about!

Would this guide work with the diagrams in the bently manual?
Its the original engine in the car (87 535i).

I kinda had a feeling that seven wires what a bit of a stretch.

All of the information I posted came from the ETM for the '86 535i. Early '87 cars (pre-9/86) use the same ETM, but later cars aren't significantly different.

[winfred]

with a b35 about 5-6 wires

[pleasefixitup]

is this for simplicity?

hope not "weight reduction"

Why the bare minimum?

[tinytim]

is this for simplicity?

hope not "weight reduction"

Why the bare minimum?

Purely for simplicity. I don't need/want any of the unnecessary electronics if they can be removed with no negative repercussions to the driveability of the engine. I pan to run an accel set up for ignition too. Would that make some of the on car ignition system removable?

[johnnye23]

Read it can be run properly on only 7 wires.

Please try this and post if it works .

[winfred]

running a ignition box would only add wiring, motronic is all inclusive. paring down the factory harness wouldn't save much as they don't really have much excess, you could pull the wires out for the temp/OP gauge (but you would need to run more for aftermarket gauge, i used the wires already in the b35 harness for the autometer units in my 81) and oil level but thats only a few OZ of copper. id leave the engine harness alone for security, its loomed and protected properly and won't fuck up unless something else intrudes upon it that was improperly positioned, a home made harness that saves a 1/4# of weight at best won't be nearly as reliable

[bimmerman78]

BMW ETM diagrams here:

http://wedophones.com/Manuals/BMW/

choose your year model and voila!

///Memo

[pleasefixitup]

maybe a bunch of wires spliced into 7 wires....

I read they found mayan gold on mars.

I'd love to see the bmw running on 7 wires....but am hesitant to say it would work.

[AWSX1686]

For an E28 535i, you have to connect up the ECU, because it controls the ignition timing and the injectors.
Bare minimum as I see it, for the 535i:
ECU pin 1: Goes to pin 1 of ignition coil. You need this. Confirmed.
ECU pin 2: Closed throttle input. If you don't care for a rock steady idle (and if you have an E28 535i, you don't) don't bother connecting this. I kept the TPS hooked up, but I think you could delete it.
ECU pin 3: WOT. Your preference whether you connect this. You don't actually need it. I think it never worked on my car, and I've owned it for 20 years. Then again I get 27 mpg, so I've probably never actually been at WOT.
ECU pin 4: Goes to starter voltage, so the ECU knows the car is being started. You can probably ground this wire instead.
ECU pin 5: Shield for reference point input. Also ground. Maybe you don't actually need it. Ground IIRC
ECU pins 6, 7, 9, 22: AFM. You need these. Confirmed.
ECU pins 8 & 27: Engine speed sensor. You need these. They're a shielded pair. Confirmed.
ECU pins 10, 16, 17, 19: Ground them all. Confirmed.
ECU pin 11: Fuel rate output. This is for you econometer. Skip it. Skip
ECU pin 12: Goes to diagnostic connector. Skip it. Skip
ECU pin 13: Goes to engine temperature sensor. You might be able to wire this across a fixed resister, but the engine won't run well at all if you just leave it floating. I left the sensor hooked up.
ECU pins 14 & 15: Fuel injector control. These signals are connected together inside the ECU, but you should probably use both as intended to handle the current. Each one goes to three injectors. Confirmed.
ECU pin 18: 12V at all times. This is so the ECU doesn't have to recalibrate itself every time it starts up. On the 535i, this wire isn't even fused - it goes straight to the battery. I'd skip it for autocross. I have this on the same power feed as Pin 35, so it gets shut off anytime the car is shut off.
ECU pin 20: Fuel pump relay control. The ECU grounds this output to run the fuel pumps. If the engine stalls, the ECU shuts off the relay. This is good, but if you want to take a chance, you can leave this disconnected and ground the relay at all times. It won't turn on the pumps unless the ignition is on anyway, but if the ignition is on but the engine is off, those pumps will be on, even if there's a fire. Your call. I have a separate switch for the fuel pumps, so I didn't use this.
ECU pin 21: Engine speed output. Goes to your tach. You don't actually need it to run the engine. I skipped this.
ECU pin 23: Shield for engine speed sensor. A good idea, but you don't actually need it. Confirmed.
ECU pin 24: O2 sensor input. You can probably skip this. I skipped this.
ECU pins 25 & 26: Reference point input. You need these. They're a shielded pair. Confirmed.
ECU pin 28: Input from auto transmission. Ground it. Confirmed.
ECU pin 29: A/C compressor on input. Ground it if (and only if) you aren't connecting it to the compressor. Confirmed.
ECU pin 30: Don't know.
ECU pin 31: O2 sensor heater control. If you're skipping the O2 sensor, skip this too. I skipped this.
ECU pin 32: Don't know.
ECU pins 33 & 34: Idle speed control. Skip 'em. I kept the ISC for now.
ECU pin 35: Power when the ignition is on. You need this. Confirmed.

In addition to all these, you need to run ignition power to the high side of all the injectors, the fuel pump relay coil and the ignition coil. Confirmed.

That's a lot more than 7 wires.Confirmed.

Hey all, I know this is a bit of an old thread, but it has been very useful as I put together my Drift e28.
I've been keeping a build thread going here if any of you are interested: https://grassrootsmotorsports.com/forum ... 209/page1/

I made some notes on the pin out above as far as what I've done. (at least what I remember) First event is coming up soon, but a little bit of driving around so far has proven this to work well. I plan to run it stock on Friday, and then install my DINAN chip for Saturday so I can (hopefully) feel the difference.

[tn535i]

Did anything above mention wedophones where you can get the ETM ?

Otherwise I think Ron gave a full list, even more than you 'need'.

[BDKawey]

Jeez you went on a trip for red betty. that thing was for sale practically in my back yard, i remember seeing the ad. where do you plan on drifting? is clublooseii in pittsburgh too far for you? about 3 hours away, might be something closer.