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Z4 E85 3.0 - 2005 - will not start!

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knmstag

Member
My son Ryan has a BMW Z4 E85 3.0 (2005). He loves the car, but we have not been able to get it started for a couple of weeks now! :(
I have checked the battery, alternator and starter motor, and all is OK. I have checked fuses & earth connections, and still no joy.
We have ordered a new ignition switch which should arrive tomorrow, I was wondering if the car key could be at fault... :|
Car is located in Burton on Trent. Any suggestions please?
Thanks - Kevin (Coventry)
 
Hi Kevin,
Someone had a similar issue last week.
That turned out to be the battery. It showed 14.1v but (I'm no electrician) it wasn't pushing out enough amps to turn it over.
Diagnosed by jumping it from another car. Have you tried that?
 
Thanks for replies.
Car is not turning over, but lights on dash and radio working. I tried using jump leads using another fully changed battery but no result!
 
knmstag said:
Thanks for replies.
Car is not turning over, but lights on dash and radio working. I tried using jump leads using another fully changed battery but no result!
Click to expand...
Well there is history of the ignition switches failing, so fingers crossed its that simple.
 
enuff_zed said:
knmstag said:
Thanks for replies.
Car is not turning over, but lights on dash and radio working. I tried using jump leads using another fully changed battery but no result!
Click to expand...
Well there is history of the ignition switches failing, so fingers crossed its that simple.
Click to expand...

That’s where I’d be leaning toward

No history of any aftermarket immobilisers fitted?
 
Sorry you’re having difficulties. How do you know the starter motor is OK? This is quite a common failure and a do-able DIY fix.
 
Thanks for message. I removed the starter motor and tested it on the bench, using a spare car battery. Earthed the casting body, positive supply on terminal post, and bridged across ignition switch terminal. Gear pinion moved rearwards and was rotating at speed, all sounded fine. I therefore assume starter motor is OK.
 
Just in case anyone needs to remove the starter motor on a Z4, you do not need to remove the inlet manifold!
It’s possible to remove it on LHS, by removing air cleaner box and air mass sensor components. Thanks to YouTube video! :)
 
The new ignition switch arrived today, was fitted, but has not solved the problem. I plan to get a new key from a local auto. key specialist, but we are feeling very frustrated, having tried various potential causes, but still baffled!🙃
 
One last stab.
Is it an auto? Wondering if it could be a failure of an inhibit switch if so? Thinking it's not in Park?
 
It’s a manual gearbox. I’m going to get a new key, as that can be a problem if it can no longer be read by the lock barrel. Thanks to all for suggestions.
Kevin
 
knmstag said:
It’s a manual gearbox. I’m going to get a new key, as that can be a problem if it can no longer be read by the lock barrel. Thanks to all for suggestions.
Kevin
Click to expand...
Is it not possible to reprogramme the old key?
Don't you have a second key to try?
Unlikely for both to fail.
 
I am the person with the fully charged battery with not enough amps to turn the starter motor. In this case I am still veering towards battery/starter motor. But the fact you tried a jump from another car does make me wonder a bit as mine then fired first turn of key. If engine is not turning it can only be a couple of things as circuit run directly from battery to starter via ignition. Not sure about failing battery in key, possibly a good try. I think these can be recharged enough by placing key next to a toothbrush charger.
You say you tested starter motor on a bench but it wasnt fitting against engine compression and additional forces. That still leads me to question the starter motor.
 
Thanks for support.
I will try a heavy duty battery from my Jaguar XJS, so worth a try. I will also check the voltage supply once again.
I plan to get one of the keys reprogrammed tomorrow.
It’s a process of elimination, albeit time consuming.
The Z4 is not the easiest car to work on! 😢
 
Don't think it will be a key problem if the engine doesn't turn over.
Edit: ignore this. See below from colb.
 
The battery I tried jump starting the Z4 was for a smaller car (1500cc), therefore I’m going to try the larger battery tomorrow. I will update this forum when I know more.
Let’s hope I can get it fixed soon...thanks again guys!
 
Battery size for jump starting shouldn't really matter if the other car has its engine running as you will have the power of the two batteries and the other car's alternator producing 14v.
 
If you are certain the starter motor is ok I would suspect that the key is not being recognised by the EWS system in order to release the starter. This could be caused by the key itself loosing the transponder inside if its not an original key and its been apart or the ignition barrel ring aeriel that reads the transponder when the key is inserted has failed in some way. The key should be able to be read by a locksmith or by yourself using an AK90+ key coding machine available on ebay. That is also capable of coding a key but in my experience its a hit and miss proceedure, I didn't manage it but others have coded keys ok. Some diagnostic code readers also have the ability to check the keys they read the key when they are in the ignition, if the aeriel is duff then it wont see the key in diagnostics. Diagnostics can also look at the EWS module and see what it is doing e.g. is it accepting the key that is in the ignition.
 
Still put my money on the starter motor if jumping from another car produces no results. Bench testing the starter will not prove it works under engine forces
 
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