E 60 528 xi 2008 Cranks but won't start - Strange
 

Car worked fine yesterday, woke up would not start. Peculiar things are happening. Key fob in- check, shifter in park- check, foot on the break= check. Press the start button car cranks has a slinging sound. Almost like its trying to start but its out of timing. Now get this....I take my finger off the start button and it continues to crank on its own. I press the button again is will stop.

It s been cold in Cincinnati (15 deg) in a garage ( maybe 30 degrees). No fault codes or CEL. Battery appears to be weak, cranks the car but only has 12.3 V. Has a half tank of gas.

Thoughts and ideas are appreciated..

Your car should continue to try to start as long as your foot is on the brake. You should only have to push the button not hold it until it starts. That sounds like a crankshaft sensor with not background information. When was the last time your battery was changed. The cold will bring out a bad battery quicker than the heat.

Hey, thanks for the info and response. I've only owned the car for 9 mos. The battery does seem weak. But what confuses me is its ability to crank the engine. Is it possible to turn the engine over but not have enough power for the other electrical systems.

I have it on a trickle charge over night, if the voltage doesn't come up I will replace it today.

Where is the crank sensor located and is there a way to test it?

Update...I used a jump box to no avail, had it cranking pretty good. All of a sudden all kind of warning lights came up, like Awd / dsc not functioning, etc.

I disconnected, waited 12 secs, then reconnected the negative battery terminal. Car started right up. Check the battery voltages with 12.57 V standing and a running measurement fluctuating between 15.2 - 13.8 V

Read on another thread in this forum about turning the steering wheel fully left then right to clear the service warnings. I think I'll get a load test on the battery for more info.

You need to read out all the codes to see if it points to something. You may need to reset them all and see what comes back. When I do this, I print out all the existing codes, reset them all and then see what reappears.

Thanks for the help. Well, its not the battery, it passed the load test at 90% capacity....The car seems to be fine now. No warnings or codes.

I expected to receive a OBD 2 dongle in the mail soon, I'll check for codes like you suggest

Just moments ago, my wife comes home from work and tells me a story. She said she tried to use the car that fatal morning. Her hands were full of things, it was cold, she was late and confused about the start sequence. Tried to start the car without her foot on the brake then just as she applied the break she removed the fob from the socket, experienced a partial attempt to crank the engine. She then repeated the whole sequence over and experienced the "crank but no start".

So know I'm thinking the car thought it was in a possible security situation and negated the start portion of the sequence. Once I rebooted it by removing the neg battery terminal it reset itself.

I would do what twh said and make sure its not just a sensor going bad.

no codes present.....thanks for the help

Sounds like you got lucky!

Yes I did get lucky....I guess the moral of this story is simple.

Before dreaming up exorbitant reasons for your problems , you should first try to just reboot the computer.:rolleyes: