Z3 Immobilised
 

Important edit before you read this thread-
It had nothing to do with the immobiliser.


My car lives outside and is subject to a lot of condensation. I went out to use it yesterday and it will start but not run. Clearly a problem with the immobiliser circuitry. (Subsequently- AA diagnostics said it is an immobiliser problem but we suspect the cam sensor) Depressing the clutch pedal (some cars have switches) and replacing the key fob battery (the detector ring on the ignition switch shouldn't need it) have no effect.
I'm now running a fan heater and dehumidifier in the car in the hope that whatever is damp and shorted will dry out and unshort.
I've read a lot of forums on "deleting" the immobiliser- anyone on here have any advice please?

i would have thought the immoboliser would have stopped it from starting at all.

Check the wiring to the 'ring' around the ignition key. Mine is loose and if the ring falls off and dangles on the wires the car won't start when I put the key in. If you can get the demist etc working that matches the symptoms I get from a dodgy ring.

A 'dodgy ring' is more likely to caused by a curry than condensation!

I can't be much help other than to say my Z3 had a Thatcham system fitted that was a total pain as it was always going off for no reason. Even if you walked passed the car it would start bleeping and making noises. There is a very good mobile auto electrician I use, he came round and removed the whole thing in 25 minutes. Now I'm back with the standard BMW system and its fine. That was the best £45 I have spent on the car !

The EWS II system on the Z3 (and other BMWs) is a "Drive-Away Protection" system. Switching on the ignition (which could be done easily by hot-wiring the switch or screw-drivering the key barrel) initiates the full start sequence with alarm off, fuel pump up to pressure, ignition made live, etc.
When the key/barrel is turned to start, the detector ring needs to read the key when the starter turns. Various codes are swapped at that time. If that is not successful, the fuel pump and ignition are switched off and the engine dies.
The car's electronics are programmed to read the right key. My correctly cut key turns the barrel and ignition switch and starts the engine but the code is absent so no more sparks or juice.
The two connecting wires on the detector ring (per WCA) disappear into a sleeve in the steering column shroud. My best bet is probably to follow them to exercise any connectors and break out the WD40.

IIRC there is a very small connector right on the back of the ring antenna.
You could start there but get some contact cleaner rather than WD40.
Have a look at the pictures in here.....

https://www.ecstuning.com/b-genuine-...a/61356965426/

When my ring drops off the steering column it dangles on two wires. I put the key in the ignition and everything seems fine but the car won't even try to start. The ignition lights etc seem fine but nothing when I turn the key. This seems similar to the symptoms you are describing which is why I suspect the same cause.

Somewhere the link between the key, the ring and the cars 'brain' there is a break.

You have replaced the key fob battery so we assume that is okay.

Is your ring firmly attached? Mine seems to be a relatively loose push fit which is why it sometimes falls off and how I discovered the issue. Try giving it a wiggle and if that works it suggests a loose wire or connection.

Other than that, I guess your are buggered :-)

Actually, thinking about this problem so more, I don't think you have an EWS problem. The EWS II module interrupts the supply to the starter motor so assuming you actually get the engine started, then I don't think it can be the EWS.
Sounds more like a lack of fuel or water mixed with the fuel. Try chucking a can of fresh fuel in the tank? Or maybe a blocked fuel filter?

Failing that you need to get the codes read as it could be any sensor like the crankshaft sensor being intermittent.

Check the wires where they would have entered the boot. They are very prone to fraying and snapping. Mine had a few broken wires which affected the central locking, not sure if it will have anything to do with your problem but worth checking.
I still don't think the car would start at all if it was anything to do with the immobiliser.

Correct!!! I proved it by trying a "dead" key which I'd had cut but not programmed. It would not start the engine unless it was used within a short time of starting with the programmed key. That confused me briefly.
So- the problem is not in the immobiliser.

The only code that persists is P0443 which relates to the fuel vapour system- I understand that it may only affect fuel consumption, not affect the running.

If it were cam or crank sensor, I'd expect to see P0340 or similar after each start. There's nothing obvious that stops the engine running. The shut-off sounds like an ignition cut. Fuel system feels OK because the engine starts instantly and strongly.

I got that info from other BMW forums relating to other models (and personal experience of it on a Ford Escort Cabrio) but it does not apply to my Z3. If the immobiliser is working, anything turning the barrel/ignition switch apart from the correctly programmed key does not start the engine.

Thanks for the suggestion. I have solved previous problems on other cars by "exercising" every plug/socket in sight.

See my other post which rules out the immobiliser.

The immobiliser ring on my car does not have a plug there- the wires are captive into the unit:
http://i68.tinypic.com/or55s1.jpg

See where the two green wire connect to the ring? That ring now falls off the steering column occasionally (thanks Dan) and although the two wire appear perfectly connected, the car wont start. Push it back onto the column and we are away.

I think you should spray the wires with contact cleaner and anything else. Try wiggling etc. A small break can cause this stuff, my hood stopped working occasional for a similar cracked wire.

I've done both and the "live" key/"dead" key difference proves that the immobiliser ring is picking up and forwarding the code.

Must have a look for that hood wire/microswitch to see if that's why the electric raise/lower failed.

Battery is OK.
Fuses are OK.
Relays are OK- pulled, no rattles and replaced.
Fuel pump is OK- healthy squirt from the fuel rail.
Found a small split in the breather pipe junction just downstream of the MAF- taped that up like this:

http://i63.tinypic.com/14mquqx.jpg

Other air pipes look OK.
Still starts strongly and then dies.
If it were a cam or crank sensor it wouldn't start.
No codes shown except the fuel evap P0443.
May have to resort to AA HomeStart.

I have just re-read your original post. You said it starts and then immediately dies.

Everything I have contributed to this thread so far is complete bollocks then. I first read that it wouldn't start at all.

I will try to recover the situation...

Let's start with first principals.

The engine needs fuel, air and a spark to ignite them.

You have checked that fuel squirts out so hopefully that is one point covered but we might reexamine this.

Air is simpler and if there are no major leaks then you are probably fine. I would still give the MAF sensor a good squirt of quick drying contact cleaner. It is just before the jubilee clip in your picture and cleaning mine took nearly 1/2 a second off the 20-80mph acceleration test.

This leaves electrics as the probably culprit. Unfortunately no-one understands electrics as you can't fix it with a hammer and gaffer tape.

So in summary, it is probably electrics but I have a niggling thought that fuel might play a part in it too.

It starts initially which means there is fuel, air and electrics.

It then dies which suggests one of the three has gone.

Air is pretty reliable so I am discounting that.
Electrics are unexplained but in my experience they either work or they don't and once they don't work then stay not working so I am holding back on that.
Fuel is necessary and is clearly there when the engine fires but possibly doesn't continue to flow so the engine dies.

Dr WCA delivers his diagnosis

Are you in the AA ?