Z4M Hotstart problem

J

Justino

Member
I have a problem with hot starting with my 08 reg Z4M. Occasionally when the car is hot it will not start. The starter motor spins as normal, but doesn’t fire. I suspect no fuel is being delivered as the car shows no sign of starting.

Two other strange things also happen. The oil temp gauge max’s out, despite the oil temp being circa 95 before switching off. The second is the sport button led flickers irregularly when the ignition is switched on, instead of turning on then straight off again. If I leave the car 10 mins, it will start as normal. Anyone else had this.

The car in the past has had a new DDE relay, but I was wondering if it was perhaps an oil temp sensor going open circuit when hot, which stops the ECU from starting the car. I also know of someone with a 911, which when hot after a track session exhibits similar symptoms.
 
Sounds like an electrical fault to me, but check the basics like that the fan runs and you have adequate coolant...
I've not had this problem and mine has got really hot on the track :?
 
The car isn't that hot, before turning ignition off the oil temp is below 100 degrees. Go to turn back on, and that's when the problem starts. Just trying to narrow down what sensor could be the cause.
 
Further developments - The car went for it MOT today and tracking. When I got there the ignition was on as they finished off tracking the wheels. I went to move it and it wouldn't start. Now the engine was cold, but same symptoms, so rules out the oil sensor I was suspecting. Maybe something else electrical which gets warm in use, and when hot cuts out?
 
Have you tried a different key, the immobiliser is in the key so worth trying if the starter isn't even turning.
 
Run a code check I think your throttle body position sensor may show a plausibility code....

These cause starting issues when they go bad..... Or long cranking.
 
Starter spins fine, just refuses to fire, no amount of cranking will make it start. I have just read codes, all clear. The key idea sounds plausible on the immoboliser (if it only cuts fuel as starter spins ok), but would that explain the oil temp maxing out and the sport button led flickering when the ignition is on when it is playing up?
 
Seems bizarre you'd get flickery lights but no codes registered, assuming it was an electrical fault..

Defo worth trying another key for a bit, I'd think about maybe swapping the battery if possible too just to rule it out, few posts recently of various random faults at ignition if it's on the way out.
 
I had a similar issue just after I bought my Z4M. The car went back to BMW and they replaced the fuel rail. I was told that faulty seals on the fuel rail were the problem. The problem was worse when it was warm though. Hope you get sorted.
 
Its not key related, I recreated the problem by turning ignition on for 20 mins, turned off, then shut car down, allowing it to go to sleep (couldn't recreate problem by quickly turning ignition off, the on again, had to shut it down), turned on, no start, swapped keys, exact same.

What was interesting, I could hear the sat nav DVD player whirring away all the time rather than stopping after a few moments as it usually does. I then plugged in the laptop to see if there were any fault codes, and the reader wouldn't connect to the car whilst the problem was there.

Its almost as if the car isn't 'booting' up properly.
 
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