Start up issue with 2004 BMW Z4

C

cheapshots

Member
Hi guys,

I am a newbie to this forum, and I really hope somebody can help!

I have a 2004 BMW Z4 2.5, which for the last 12 months has been running like clockwork. However for the last 6 weeks, I have had an intermittent problem that is progressively getting worse. When I turn the ignition key, you hear the normal clicking, the 'eh-eh-eh' and you hear the engine trying to start but it won't.

I took it to a BMW specialist, who ran a diagnostic check, nothing picked up, he suggested we start by replacing the cheapest part - the relay, which we did however the problem still exists.

Whereas before the engine would start 7 times out of 10, it is now 2 out of 10. The specialist I went to suggested it might be the fuel pump however he couldn't be 100% certain.

I am taking the car to the garage tomorrow morning so your advice would be highly appreciated.

Cheapshots
 
cheapshots said:
I took it to a BMW specialist, who ran a diagnostic check, nothing picked up, he suggested we start by replacing the cheapest part - the relay, which we did however the problem still exists.

Whereas before the engine would start 7 times out of 10, it is now 2 out of 10. The specialist I went to suggested it might be the fuel pump however he couldn't be 100% certain.
Click to expand...

What a pants specialist, just start replacing parts after the computer says 'no'

Did they charge for the relay and/or pump, or did they try one from their spares/stock?


Can't really help I'm afraid, but I'd let BMW use their flow-chart diagnostic method to resolve the issue, as looking at them they offer perfectly logical fault fixing paths (which this specialist should be using, imho)
If the car runs and starts perfectly normally, but intermittently doesn't start right, then the problem should be fairly easily diagnosed imho. Did they check the readouts of the sensors to check they were all behaving and reading right for the current engine state? Certainly an intermittent issue that doesn't dwell once the engine is actually going (so likely the starting circuit)... immobiliser feed (cuts fuelling but still tries starting) from ignition barrel?

Dave
 
Hi,

The car is not an auto, and yes he charged me £80 for running the diagnostic test and replacing the relay. I'm not sure if they checked the readouts....

Arghhh! I just dropped the car off to the specialist, he said he would call me later to update me. Thanks for your help guys, lets hope it can be sorted once and for all!
 
£80 to plug it in to look for faults when any major ones would flash up on the dash anyway, AND charging to mis-diagnose it.

Lame. Sorry, but if people can't diagnose things properly they shouldn't charge as if they can. A relay takes 2 mins to swap and see if it solves the problem, if not, replace the old one back again.

Grrrrr...

Hope it gets sorted cheaply now for you. Ie, pay just for the parts that were broken, not all the bits that they think were broken and replaced trying to make it work... :x

Dave
 
Im sure n1k_85 had this problem a few months ago - have a lookie here:
http://www.z4-forum.com/forum/viewtopic.php?t=9655

Edit: Sorry N1k's starter wasn't even turning so its a different scenario!

Id have a whiff of the exhaust while its turning over, thats a good indication as to whether the injectors are firing (flooded engine?). Also try a different key as the immobiliser may be not allowing it to start.

That's where id look first - If no fuel smell, check voltage over the injector rail (and plugs while youre at it). If theres voltage, then you need to check the fuel pump...

Good luck with it :)
 
There is still a "kill" switch on manual tranny cars-need to have clutch depressed. Did he check that sensor??
 
Smokin said:
There is still a "kill" switch on manual tranny cars-need to have clutch depressed. Did he check that sensor??
Click to expand...

Not in this country there isn't, we are trusted not to start the car in gear :lol:
 
Smokin said:
There is still a "kill" switch on manual tranny cars-need to have clutch depressed. Did he check that sensor??
Click to expand...
If you dont hold the clutch, it wont turn over, which he is stating it is doing.
 
Kaide said:
Smokin said:
There is still a "kill" switch on manual tranny cars-need to have clutch depressed. Did he check that sensor??
Click to expand...
If you dont hold the clutch, it wont turn over, which he is stating it is doing.
Click to expand...

hmmmmmm.

Any update? Would bad coils prevent starting or just make it run rough as heck once going? 2004 and the 2.5 engine makes it in the ball park.

I do agree that a "professional" should use a flow chart to diagnose and not "shotgun" it by replacing bits to see if they fix it. Had one place do that on another car, and they never fixed it properly.
 
Hey guys,

I'm not sure about the 'kill-switch' sensor...I've left the car overnight with the garage. Apparently they picked up a discrepancy with the power supply to the fuel pump, but they wanted to check a few more things before they get back to me. Here's hoping.... I will update you when I next hear from them.
 
I was gonna say crank shaft sensor, but it would have to work perfectly all the time the car worked properly, but just have an off-day when it wouldn't try to start the car :)
Ie, no random cutting out has occured while in operation, so once it's started it's fine it seems, full stop.

Still, it wouldn't surprise me, sensors can do really odd stuff when they are on their way out...


I'm still thinking immobiliser circuit. A loose connection between ignition barrel sensor loop return to ECU to unlock it and allow injections to take place. Cranking will be allowed, just injections won't be.

Dave
 
Hi guys,

I just got the car back from the garage. Here is what I understood - they have ruled out a faulty fuel pump, however, the problem lies in electrical signal to the fuel pump.

The signal, originates from the 'ECU' to the fuse box and a relay within the fuse box sends the signal to the fuel pump. Now as the problem is intermittent, the car decided to work nearly every time for the whole 5 days it was with them! Just my luck.

The garage changed the relay inside the fuse box and it seems to be working every time. He did say that he still cannot be 100% certain that the problem is fixed and he cannot carry on testing because the car starts every time now! At least the problem has further been narrowed down I guess.

The garage would not accept payment and they suggested I have a trial run with it for about 10 days and if everything is still working, I can pay them for their services, which was very nice of them.

If anyone wants the contact details for the garage just PM me. They are based in North West London near Brent Cross
 
Sounds good, but didn't they already swap a relay? What was the other relay that was swapped?


Good that it seems to be fixed anyway :D

Keep us posted as it's good to know the resolutions to these problems :thumbsup:

Thanks

Dave
 
I'm not very technical, but I think he first changed the main relay and this time the relay within the fuse box?

I tried to start it up tonight...the shock, the horror.......the same problem AGAIN!!!!! It started the third time trying :(

The garage did say that they were not 100% certain it would be fixed, I'm going to grin and bear it for a few more days, then take it back to them.

I cant explain how frustrating it is, to sit in the car and pray to God it starts first time! Has anyone got any advice?

In the mean time, I'll keep you guys posted
 
My advice is take it somewhere else.

So it started the 3rd time trying, can you be more specific.

Did you hear the fuel tank pump priming on stg2 ignition the first two attempts that it didn't start?

Was it different the 3rd time when it worked?


In theory this problem should be easy to find because the car DOES work, it's just intermittent. Not THAT many things are in there that will intermittently cut fuelling.

Dave
 
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.
 
I am very tempted to take it somewhere else, however I really need this to be fixed ASAP, and I feel the garage know my car pretty well, so if anyone can fix it, I hope its them!

Sorry I can't recall more detail re the ignition. All I hear when I start it, is the engine cranking - that 'eh-eh-eh' sound, but it does not fire up. I do not do anything differently when I try again.... I tried keeping a diary of when it fails to start, believe me, its completely random.

I am not sure what the fuel tank pump prime would sound like, although I have been assured that the fuel pump is working normally, its just the power supply that goes to it that seems to be the problem.

I have called the garage again, I will be taking it in later this afternoon. I've got to the stage where I borderline hate my car :(
 
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