’93 525i not starting,immobilised?

My '93 525i was idle for a few months. Battery had gone flat.The car was
jump started and ran for maybe 30 seconds and stopped on its own.
Thought it was out of petrol but unfortunately not!It would then start for
half a second and just cut out again.A diagnostic check was done to see if
it was immobilised but nothing came up at all. While the car was plugged
in an earth wire was spotted just barely hanging on . this was repaired
and the car started but maybe on 4 or 5 cylinders. Think the jump leads
had broken this while it was connected to the engine. Disconnected this
wire and the car still ran but still not 100%.Now the car is only on 3
cylinders max! The other day i tried easy start to see how it would run but
didnt even fire like there was no spark.I have almost given up on this but
would like to know has anyone came upon this before or any help would
be greatly appreciated!Thanks in advance.

Cheers for the quick response Nigel.It seems to be a spark
problem.Cylinders 2 and 5 are the only ones firing.I swapped around
plugs
and coils but the spark still remains only on two and five regardless of
which
coil is where.The plugs are gettin wet also so would look like the injectors
are workin.I took a coil out while the car is running and put a plug in
earthed it off the body and there was a tiny spark from the electrode to
the
body but only just.This coil was originally from cylinder 2 so was workin
fine.The wire which was broke by jump leads is an earth goin into the
loom
where the wires are for coils and injectors.Dunno if anyone came across
this
before or could shine a little light on the subject!

Just to add to the post I think i might have found the problem.On opening
a plastic cover in front of drivers steering wheel under the bonnet a
strong burning smell was present.Under this cover appears to be 3 ecu's
or electrical boxes.The one which was burnt is a has bosch on the outside
.I was in a breakers yard but the car there only had one box with the last
number different of the bosch ecu.Would anyone have one of these or
know where i could pick 1 up,the number on the box is 0 261 200
402.The local breakers only had 1 of this model and I wouldn imagine
there plentiful! Any help would be great.

Edited by HEADGASKET

Just to update this my ix is now running again! An ecu from ebay plugged
straight in and car started Unfortunately it still didn run on all
6.I pulled each coil off each plug and found the one not working.When
looking at this one side of it was melted pretty bad in one small spot,i'm
thinkin this is what burned out the ecu! I checked the other 5 and another
one had a slight bulge in it the same place the other one had melted. I've
replaced these and car is running fine now.Hope this might help someone
down the line and much appreciated replies. Thanks lads.

Sounds like you might have fried the ECU and coil pack on jump starting it.

This can happen but is rare.  I have heard that switching on side lights on both vehicles can eliminate the voltage spikes caused by jump starting. i.e. the side lights blow first taking the spike out of the voltage when you crank the dead vehicle.  Side lights are much cheaper and easier to fix than an ECU!