Start up issue with 2004 BMW Z4

3.0 Si Anderson said:
Mr Whippy it is too easy to say take it somewhere else and they should use flow charts etc...it is just not as simple as that. With cars nowadays ever more reliant on internal diagnostics if the problem is not obvious and the computer does not identify the issue then a lot of it is trial by error. The mechanic will make the best and most educated call on what they think may be the issue and see if that works. Generally an indy will try the most obvious options (these are very often the cheapest solution and 9 out of 10 times will cure it) rather than replacing whole parts which the stealers do. Do not kid yourself that you get better or more educated service at a stealer as those guys are just parts replacment technicians. I know of horror stories of stealers looking over £1k to fix a car that needed a £14 part and 20 mins of labour. There are loads of examples out there when a car works fine in the garage and half an hour later it is on the blink again. It will take time and patience and it is worth remembering that what he had done at the indy would have cost twice that at the stealer and they would most likely have done exactly the same. It can and will be trial and error.
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BUT, a specialist should be trialling these easy/cheap part fixes with their own known good spares. Charging lots of time and even cheap parts to not fix it is, imho, lame.

Trial and error, imho, is sensible, if it's done scientifically and logically. It clearly wasn't because it's still broken, despite days to test it.

Yep, a dealer might be no better, but they will resolve the issue using the engineers flow charts for problem resolution. They made the car, they made a sensible diagnostic flow chart to resolve it.


Personally, I'd get a hold of the flow-chart and start going through it. I've diagnosed cars before, and resolved issues, and shotgunning parts in even if they are cheap, is not the solution.
What happens now is that you might think the new parts could be faulty too, or perhaps another part is forcing them to fault/fail... they are just charging you to pay for their mistakes and inability!


Sorry, bit of a pet hate this. If I knew I couldn't fix it, I wouldn't take the work on. The garage has proven they are useless.

Dave
 
Hi guys,

Bit of an update maybe. Since my last post, I haven't taken the car back to the garage because the guy was away for a few days. However, since then I have come to realise something, I've found a pattern.

If I put the key inside the ignition, and turn to it the position just before the engine starts (I think that's position 2?), then wait. The lights on the dash briefly come on, the petrol indicator moves - all the usual stuff, then you hear this low hum for about 4 seconds - I think that's normal too.

Anyway, after all that has happened, if I then proceed to turn the key to start the engine, it starts first time, every time !!!!

If I try starting the car without leaving the key in that position long enough to do all that mentioned above, it will do its normal thing and not start.

Interesting eh?

Cheapshots
 
My brother had immobilizer issues with his motorbike when he had his BMW key and the key for his Blackbird on the same key ring, close together. Seems there was some interference between the two. Do you have other keys on the key ring that might have a similar effect? Maybe RF security badges could cause the same problem?
 
jhbuining said:
My brother had immobilizer issues with his motorbike when he had his BMW key and the key for his Blackbird on the same key ring, close together. Seems there was some interference between the two. Do you have other keys on the key ring that might have a similar effect? Maybe RF security badges could cause the same problem?
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No other keys on my keyring and I have tried using the other key I have - same problem.
 
I've been trying the spare key, even thought I've tried it before....same problem.

That method of starting the car I previously mentioned still works, every time. I will take the car to the garage on Monday.
 
cheapshots said:
Hi guys,

Bit of an update maybe. Since my last post, I haven't taken the car back to the garage because the guy was away for a few days. However, since then I have come to realise something, I've found a pattern.

If I put the key inside the ignition, and turn to it the position just before the engine starts (I think that's position 2?), then wait. The lights on the dash briefly come on, the petrol indicator moves - all the usual stuff, then you hear this low hum for about 4 seconds - I think that's normal too.

Anyway, after all that has happened, if I then proceed to turn the key to start the engine, it starts first time, every time !!!!

If I try starting the car without leaving the key in that position long enough to do all that mentioned above, it will do its normal thing and not start.

Interesting eh?

Cheapshots
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That hum is the tank pump priming the fuel lines etc... maybe it's just a bit worn and taking longer to get pressure up?!

Not an expert in this area much, but you have found a fairly strong piece of info there, the garage really shouldn't have much problem finding the fault now I wouldn't hope.

Dave
 
Hmm only other thing I could suggest other than crank angle sensor and fuel pump would be a faulty fuel pressure regulator. 4 seconds seems a little long to prime so perhaps either the pump is failing or the FPR is letting too much fuel past and back to the tank and preventing operating pressure from being reached.

Is it any different with the fuel cap removed? Does the Z4 operate a pressurised fuel tank - i've not noticed a woosh when opening the cap.
 
Thanks for the advice guys. I'm fed up with this beautiful bloody car :headbang:

I HOPE the garage will now be able to figure it out when I take it to them on Monday. I haven't tried starting it with the fuel cap removed, I'll give that a go a few times today though. I haven't noticed a woosh when opening the fuel cap though...

Most people have suggested a failing fuel pump, but the garage said the pump itself was fine, and that it was the electrical signal that tells the fuel pump to start that is faulty.

If there is a faulty electrical signal then why does it start every time when I use the starting method described above (turn the key to just after position 2, wait for dash lights to come on and the fuel pump hum, then start) ???!!!
 
Definitely sounds like your Fuel Pump is working fine but not quite priming the lines quick enough... Can you hear it priming in the morning?

It could also be a partially blocked fuel filter? Have you run any Fuel system flush through it recently?? They often knacker fuel filters! :roll:
 
EdButler said:
Definitely sounds like your Fuel Pump is working fine but not quite priming the lines quick enough... Can you hear it priming in the morning?

It could also be a partially blocked fuel filter? Have you run any Fuel system flush through it recently?? They often knacker fuel filters! :roll:
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Yes, I can hear it prime every time I try leave the key in position 2 - whether its in the morning or at night.

The first garage I took the car to which must have been over 2 months ago now, couldn't figure out what was wrong with it. I told them I do maybe 300miles a month and their advice was 'give it a good thrashing' then poured in a fuel system flush...

Hmmm....I'm taking the car back to the specialist today, I will run these idea's past him.
 
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