I'm sitting at Heathrow airport (dump for anyone who hasn't been there) waiting to fly to Vienna to meet my German friend who bought me some new wires/HT leads from ebay.de (i'm not going specifically for that, that would make my €17 wires very expensive!). Reason i bought them is that I have one non-standard lead that sticks out of the distributor cap which means that the protentive cap doesn't fit. I'm planning on replacing the wires and plugs this weekend, but i was wondering what that wire/pipe does that hangs off one of the HT leads and seems to connect to something near the oil filler cap? Anyone know?

That is the impulse sender for either the #6 or #12 cylinder (You have one on each side). They plug in under the oil drip cover, along with the Crank Position Sensors (CPS).

Its actually a "doughnut" of sorts (inductive pickup coil) that surrounds the HT lead on # 6 and 12 as already indicated........be care ful with the plugs which are clipped together under the oil filler cap overflow as they can be very brittle with age.............dont force anything and take your time...

thanks. what does it actually do?

has to do with the timing, so the DME's and EML know when the cylinders are actually firing ( along with the CPS sensors)

Well I made a total mess of it. I didn't listen to Pumped's advice and i just tried to pull the plug off. The thing just dissintegrated, i didn't use much force it just fell to pieces. Worse still I realised that it was in fact the crank position sensor plug that i had destroyed not the impulse sender... I am a total idiot. I've soldered the three wires back onto what's left of the plug and wrapped it all in insulation tape. Anyway due to the constant rain in England and the fact that I just made the whole situation worse i've given up for the day. I really need to learn to be more careful with my baby and take more time :(. Anyone got any idea how I can do a better repair than insulation tape? Can you buy the plugs? I couldn't find them on realoem. The car is running OK but i'm worried that it won't last.

If it stops raining i'm going to have a go at the plugs and leads tomorrow.

Nick,
Here is some very good advice for you in the future: These cars are actually nice to work on, things that need excessive force to assembly or remove means that you are doing it wrong and will cause more damage. The CPS sensor sonnector (as well as the impulse connector) pull off quite easily - you just need to push down on the little wire "bridge" that runs across the top of the connector, this "unlocks" it. As for soldering and taping - please only do that as a last resort/ temporary fix until the new part arrives. You can get new CPS sensors from: www.autohausaz.com (http://www.autohausaz.com) . The ones they sell are the "new" style which are easier to install. It is only a matter of time for a failure here, and then you won't even be able to start the car.
It is one of those things that can be considered a "learning" experience - too bad those usually wind up costing us money.

Good luck.

You're right GR8White. I'm fed up with learning though and just want a few things to go smoothly. I think my major issue is a lack of time and a lack of usable garage. I may have to pay someone to do some of the things that need doing urgently. Great advice though and thanks for trying to help me. As for the CPS, the wire from the plug seems to disappear into the engine, is it a reasonably easy thing to change? Bear in mind I am a novice although that's probably coming through loud and clear!

CPS aren't that difficult to install. The wires run down the right side of the engine (as seen from the front) and end at the 2 and 5 o'clock position arond the cranksgaft pully. You will have to loosen the power steering pump in order to get the old one out and the new one back in.

Here is a helpful site for you (http://bmwe32.masscom.net/) if you want do some more DIY things on your car. It uses a 750 but the eights and sevens are very similiar.