M20 b25 conversion no spark help please?

[Speedtouch]

That's correct, according to the Zone Wiki pinout.

Also test for an ignition switched +12V at pin 20.

[Brianmoooore]

For some reason only known to the designers of this old management system, they decided to design it with switched ignition live reaching the engine loom by two separate routes, one supplying part of the engine loom, and the other supplying the rest.
One route is via the C101 20 pin plug and socket next to the fusebox, which feeds the coil, and the other route was a complicated one, through several plug and sockets behind the dash, but eventually connecting the the engine loom via a three pin C104 plug (not to be confused with the immobiliser C104 on facelift cars) near the ECU. This appears to be what the loose green wire you've found is for.
Since your car loom does not have any of the C104 wiring behind the dash, thread the loose wire back from where it is, and splice it, at some convenient point, to the green wire running from the C101 to the ignition coil.

Relays: Replace the two relays on your loom with the ones from the 318i. Orange one is the fuel pump, and should have the same layout as the one you are using now, but without the centre 87 pin, and the white DME one should be the same as your existing one, but with 30 and 86 transposed.
This will result in battery live going to pin 30, and the switched ignition live going to 86. The coil of the relay is connected between 86 and 85 (brown=earth), so when the ignition switch is turned on, the relay will click on, and connect the battery power on 30 to both 87s. One 87 provides power to the ECU, and the other feeds the injectors and the coil of the pump relay.

From your last reply, it does seem that your battery would have been slowly draining via the permanently powered DME relay coil.

After all this, I still don't expect the car to run, but I assure you we are getting nearer by sorting out the bodged up wiring. When it's all wired as it should be, hopefully the fault will be easy to find.

[Mitchen]

Once fixed this should be zone gold! Epic Tech Help thread!

[Benten]

Ok so I have done as u have said, iv joined the wire to the ignition live

Placed the orange relay in fuel pump plug and switched the DME as the pins were different so that's all done now

[Brianmoooore]

Turn on the ignition, and confirm that the DME relay clicks when you unplug it and plug it in.
I take it the engine still doesn't start?
Check that there is still no spark when cranking.
Check that the fuel pump still doesn't run when cranking.
Swap over the two bell housing plugs and try again.

[Benten]

Can I say Brian your an e30 wiring genius and thanks to everyone else who has helped,by now you have probably guessed I have a spark and live to the fuel when cranking.

I put a live to the green and purple that fired when cranking
The DME relay clicks as removed and replaced iv changed the two cos plugs around and bingo I have spark

I won't be firing it up tonight as it's a bit late now but will be on it 1st thing in the morning and let you know how it gets on.

Thanks again guys, if I could buy you all a drink I would!!

[Speedtouch]

Sounds promising...

[RM2186]

I've not helped, but I've been an avid reader of this thread.......... can I have a pint of lager

[kam-325i]

OMG......Please fire up !!!!!

This one fried my head.....

[Mitchen]

Did anyone else who read this scream at the OP to fire it up and not wait till the morning

[Benten]

Ok so are you ready for the news!!!

Got up at 6am this morning due to me being eager f***k, made sure it was good to go, put the spark plug back in checked oil etc.

I took a little bit of easy start, but it has just fired up, sounds a little lumpy but has no filter or sensor conenected

Thanks everyone for all your help, I can take the lump back out now and get cleaning and painting.

[Grrrmachine]

Exellent news, and well done!

If the lump's coming out you might want to think about upgrading the ECU to Motronic 1.3. It's a better management system, and it will replace your currently shonky engine loom to give you more peace of mind.

How To guide here:

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

[Benten]

Thanks, I can't believe it running, hmm I'll do this as I want to run at it's best thanks for the advice

I don't know if I should make a new thread for this but when I brought the doner car with the 2.5 in, I had everything but the diff, iv done some swapping and changing of the prop and got it all to bolt up but will the 1.8 one be any good, if not what would be the best to go for?

[Grrrmachine]

The 1.8 diff will make your car go forward, and although the ratio (4.45 or 4.27) combined with the 325i gearbox will give you incredible acceleration, but a low top speed and terrible fuel economy.

Ideally you'd want a large-case 3.91, 3.73 or 3.64 diff from any other 325i. Stick an ad in the Wanted section and you'll get plenty of offers.

[Brianmoooore]

Special thanks should go to kam-325i as well for posting up the pics. Without those, I would't have picked up on the incorrect relays, or realised that the wiring to the relay socket was incompatible.
I did think of suggesting a change to Motronic 1.3 right at the beginning of the thread, as a simple way of solving the problem, but thought that would be a bit defeatist. 1.3 really is a big step on from 1.0 - almost as big IMO as the jump from 1.3 to what's used today. 1.3 is still very basic, but contains most of the elements found today, albeit they have now been developed considerably.

I've been checking up on the green relay, which I presume has part number 61 36 8 373 700. This is the relay that BMW sells as, and is shown in the ETK as, a direct replacement for the white DME relay used in E30 325s from March '85 onwards.
BMW are wrong! This relay is only suitable for use with the later Motronic system, when the wiring was changed to accommodate the DME relay being switched on by the ECU, rather than directly by the ignition switch. This involved changing the DME relay wiring from '12V + to operate', to 'earth to operate', which resulted in pins 30 and 86 on the base both being connected to battery +, so not mattering that 30 and 86 had been swapped on the base.

[Benten]

Yes definatly I f it wasn't for kam-325i I wouldn't of heard of you and wouldn't have tried posting it so thanks, all help has been much appreciated

So what will the benefits be with a motronic 1.3

[Grrrmachine]

From the link I posted:

Benefits

The main thing anyone is going to want to know is why upgrade to M1.3 from the earlier systems. If your car is running fine as it is and you are happy with keeping it original, both in terms of performance and function then there probably isn't that much point in going to the effort. However if you are looking to increase performance or you are having running issues then it might be a good option, some may say necessity on the performance side of things.

Ӣ Improved accuracy of sensors and event timings for better fuelling and timing.

Ӣ Capability for a lambda to be fitted.

Ӣ Ability to remap chips for increased performance.

Ӣ Able to run a MAF instead of an AFM, again for increased performance.

Ӣ Better fault-finding with reduced number components with a sturdier construction.

Ӣ Better replacement parts availability.

That last one is becoming increasingly important as these cars age, as it's a lot harder to find those gearbox sensors you have, compared to the M1.3 crank sensor.

[kam-325i]

Thank god for that !!!!!

I think all the thanks should go to Brian and Grrrrmachine, I just pointed Ben in the right direction....I would have never found that bodge in the fuse box...