Crank sensor not working? No spark or fuel help

[Lukehudd]

So I just put an M 20 engine in my 318 I the ECU is in and all wires seem to be connected however there is no fuel or spark when the engine turns over my crank sensor is on the side of the bell housing I think?!? From the research I have done as it is not on the front where everywhere suggests any help with what to do next thanks

[Brianmoooore]

Welcome to the zone. There are many reasons why you could have neither fuel or sparks after an engine swap, and crank sensor issues are amongst them.
Early M20 engines had two crank sensors in the bell housing, with another sensor at the front which is only used for diagnostic purposes.
Have you transplanted the engine and gearbox complete, including flywheel, the engine loom and matching ECU , all from the same donor?

[Brianmoooore]

Hi! I've seen your PM. To reply on the thread, just type into the 'quick reply' box below and click submit. I'll get an email to say that there's been a new post.
First of all, there should be two identical sensors in the bell housing, with two identical plugs that can be connected the wrong way around. These sensors aren't particularly reliable, but you can measure the resistance of both, which should be identical. They rely on a magnet set into the edge of the flywheel to work, and this magnet has been known to fall out. The flywheel also has to be an early type, since later flywheels don't have a magnet.

[Lukehudd]

Hi thanks for that, I'll check them tonite and maybe get some new ones, just wondering how many earths should there be on the engine as somone I have spoken to says tcould be an earth that isn't on but I can only find the earth from the top strut to the better and one from the side of the engine near the engine mount to the inner wing thanks

[Lukehudd]

Welcome to the zone. There are many reasons why you could have neither fuel or sparks after an engine swap, and crank sensor issues are amongst them.
Early M20 engines had two crank sensors in the bell housing, with another sensor at the front which is only used for diagnostic purposes.
Have you transplanted the engine and gearbox complete, including flywheel, the engine loom and matching ECU , all from the same donor?

[Lukehudd]

Hi thanks for that, I'll check them tonite and maybe get some new ones, just wondering how many earths should there be on the engine as somone I have spoken to says tcould be an earth that isn't on but I can only find the earth from the top strut to the better and one from the side of the engine near the engine mount to the inner wing thanks

[Brianmoooore]

First of all, throwing new and expensive parts at a faulty car, with no proof or evidence that the existing parts are faulty, is not a good way of fault finding. It risks creating new faults, and is extremely bad for the wallet.
There is only one main earth cable from the engine to the body, and the cable on the strut from the body to the battery negative. If the engine cranks over properly on the ignition key, then there is nothing wrong with these.
The engine loom requires battery power and earth.
The positive wire is red (under a black outer sleeve), and goes to the battery + terminal.
The negative wire is brown or brown/orange, and connects to the top of the turret with the negative battery cable on the later facelift engines, but on your early engine, connects to the engine on the left hand side, above the starter motor.
The DME relay is a white 5 pin relay, mounted on the LH inner wing, near the air meter. Does this relay click when you switch the ignition on? (Turn the ignition on, and pull the relay from its socket. It should audibly click when you pull it out, and click again when you push it back in.)

[Lukehudd]

Thanks I'll try that tonite and take in your other advice much apeciated, do you know anywhere I can buy a crank sensor as I have snaped mine, thanks

[Lukehudd]

I've checked my dme with the ignition on pulled it in and out a few times and listend for a click, there was no noise I have already took one sensor out would this cause there to be no noise thanks

[Lukehudd]

Also I think my dme is grey it's next to my fuel pump relay it is 5 pin

[Gavt]

If the battery is in the boot there is fuseable link off the positve lead tuckedbehind the carpet and wraped in black insulation. If this has blown it will not allow power to the dme. Easy to check with a volt meter or a physical check to see if the the fuse has blown. Not sure if this fuse exists on the front battery.

[Lukehudd]

My battery is in the front unfortunately, I'm abit stuck now

[Brianmoooore]

Replied to this last night, but once again it looks like I spent several minutes typing out an answer and then forgot to submit it!!!!
Battery won't be in the boot unless you moved it there, 'cause this is a converted 318, not an original 325, and there's no fuseable link in the engine loom supply when the battery is in the front.
Assuming that you've found the DME relay and it doesn't click, this needs investigation, since it should.
Wires to the DME relay should be green, brown, red, red/white and red/blue.
Connect a small 12 volt lamp (tail light bulb, interior light bulb, etc) between the red wire and the brown wire and confirm that it lights.
Turn on the ignition and connect the lamp between the green wire and the brown wire and confirm that it lights.

If you need a new crank sensor, either try the trusted traders on here for a second hand one, or I think autodoc.co.uk (based in Germany, in spite of the uk email address) list new ones. Check carefully that you're not buying the later type.

Do you know the age of your engine and box? It'll help if we know exactly which version of the engine management system you have.

[Lukehudd]

Hi thanks I'll try what you said tommorow night and yes it's 1987 so the year the engine changed to the other crank sensor I think? The reg the engine came out of is E471 NEX thanks I'll Let you know how the testing of the relay goes tommorow

[Lukehudd]

Hi Brian, I have done as you said the bulb lights up between the red and the green wire however I then turned the ignition on and test between the brown and green wire. The light did not come on where should I go from now, thanks for your advise

[Brianmoooore]

You may be turning the ignition on with the key, but the ignition 'on' feed doesn't appear to be reaching the engine.
Do you have a round 20 pin C101 engine loom plug and socket, just to the right (looking towards the front of the car) of the fusebox, or the older rectangular version?

[Lukehudd]

Yes I have the round c101 plug u plugged my new m20 one into the original 318 bottom one

[Brianmoooore]

Unplug the engine loom and connect the lamp between pin 7 (green wire) of the socket (bottom half of the plug and socket) and a good body earth, such as the bracket the bonnet latches into, with the ignition on. Does the lamp light?

Scrub the above! There's an easier way. Connect the lamp between the + terminal of the ignition coil and a good body earth, such as the main earth point on top of the RH front suspension turret, with the ignition on. Does it light?

"C104" may enter this conversation shortly!

[Lukehudd]

Hi Brian I did both of what you said it lit up on the green wire it also lit up on the positive of my ignition coil however it also lit up on the negative of my ignition coil also ( I havnt changed any of my pins in the the twist plug I beileive to be the c101 but I have heard other people have thanks )!!!

[Brianmoooore]

The power is fed to the + terminal of the coil, but when the coil isn't being triggered the power can flow straight through the coil primary winding, so the lamp will light on the negative terminal as well, although it will be slightly dimmer.

Right, this is where C104 enters the conservation! You are looking for a small three pin plug which is part of the engine loom, and should be behind the instrument cluster/above the engine ECU. It would have connected to a matching plug, coming from the wiring to the instrument cluster in the engine's original home, but this plug will not be fitted on your 318i body looms.
When you find it, I need to know the exact colours of the three wires.

[Lukehudd]

Hi I think this is the c104 you were talking about. There is a black/blue , white and green wire thanks

[Lukehudd]

It isn't plugged in to anything and never has been just to let you know

[Brianmoooore]

There's nothing to plug it into in its current home, but when this loom was in the 325i that the engine came from, I'm fairly sure it was connected to a matching plug. If you still have access to the donor car, it would be useful to obtain that plug and several inches of the wire attached to it.
Use the test lamp to check for power between the green wire in this plug and a good body earth, with the ignition on. I don't expect the lamp to light.
If this is the case, connect a piece of wire to a 12 volt power source, such as the + terminal of the battery, an connect the other end to the green wire/pin in the plug. Now pull out the DME relay again and plug it back in, and see if it clicks now.

[Lukehudd]

Okay thanks very much I'll try that when I get home, I don't have the donor car but I'm sure I can get around that problem I'll be getting some wire today, should I get any for the other two pins blackblue and white or will they be left ?

[Lukehudd]

Also the crank sensor still isn't it as it is coming tommorow will this effect the relay at all

[Lukehudd]

Hi Brian, I did as you said and there was no light so I attatched the green wire. This black cylinder shape attached to the intake started buzzing so something is definatly starting to happen ! The DME is also clicking

[Brianmoooore]

Early E30s had a rectangular 17 pin C101 connector. As the engine management became more sophisticated with time, this connector had insufficient pins for the engine/body interface, so the 3 pin C104 connector was introduced to supplement it.
Eventually, the rectangular C101 was superseded by the 20 pin round version with sufficient pins, but unexplicitly, BMW still kept the C104 as well for a short while, before eventually eliminating it and transferring its functions to the extra pins in the round C101.
Your engine loom is one of the ones with the round C101, but still has the C104.
Permanently connect the green wire in your C104, by a splice, to the plain green wire that you will find coming from the other side of the plug and socket from the ignition switch, which should be found clipped to the steering column, about half way down.
After this is done, and the damaged crank sensor is replaced, hopefully the engine should start and run.
The other two wires in the C104 should be the engine speed (revs) signal and the fuel rate (injector pulse width) signal, which are required by the instrument cluster. The colours you gave me don't match my wiring diagrams, but that's not unusual or anything to worry about at this stage.

[Lukehudd]

Thanks very much, would you recommend connecting it to the c101 (bottom half I presume? Or strait to the green wire on my steering column

[Stephenmoooore]

No reason why you shouldn't connect to the wire by the column.

[Lukehudd]

Hi guys is it a green wire in this loom up the column thanks

[Lukehudd]

I don't want to start messing with the loom if it it's not the green wire in there I carnt imagine that would end well so could you let me know if it is that one thankyou

[Brianmoooore]

Any plain green wire would do, because they should all be ignition switched live, but the one I'm on about is part of a loom of only about six wires. The main wires will be plain red, plain green, plain purple and black or black/yellow, and it should go behind the steering column shroud, coming from the ignition switch.
I'm far more familiar with the post facelift E30 looms than the pre facelift ones, but AFAIK both are similar in this area.