Intermittent crank but no start

Lozza47 · 02-03-2022, 01:20 AM

Hi all,
I was driving my 2010 320d through a bad rainstorm and ever sense then, occasionally on cold start, after pressing start, the car will pause for 5 seconds then start cranking endlessly, no start with every single fault warning (drive fault, traction control etc) in the idrive.
I then let the car sit for about 30 seconds and the car turns on fine no problem no existing stored codes.
I'm unsure how to diagnose what is wrong because the car still seems to work fine it's just intermittently this happens on cold start (being left sitting over night for instance).

Previously I've had the dme replaced due to water damage and the mechanic drilled holes in the bottom of the ecu compartment to help drain water.
I don't think the ecu is fried because it still occasionally runs no problems at all.

Any thoughts?

Lozza47 · 02-08-2022, 11:18 PM

Just another update, had the DME replaced with a second hand unit and coded in. Everything back to normal.
This is the second DME that has failed in this car. There was no sign of water or dirt in the ecu box which is odd.

Any suggestions on what else could cause DME failure?

Owen81 · 02-12-2022, 08:30 AM

Could be a short somewhere else in the system. If you had that much water in your sealed ECU box, how much did other areas see?

There is a reason flood cars are written off immediately, it may seem like there is a quick fix but you can experience electrical issues for the remaining life of the car.

thalastdon1985 · 02-12-2022, 07:42 PM

If your windshield has been replaced, it is likely the seal at the bottom isn't secured. It appears to allow water to flow into the dme area. Every e90 I've seen with a water damaged dme has had this condition.

Lozza47 · 02-12-2022, 09:18 PM

Thanks I will check the windshield seal. The first time plenty of water got into the ecu box however this time round there was no signs of water or dirt in the box suggesting dme not have actually been water damaged. I also had the bmw specialist clean the water channels and still a larger drainage hole. The lower steering rack did get quite a bit of water on it but not sure how that could've short it. Any way to diagnose a potential short or is there too much complexity to narrow it down?

Lozza47 · 02-13-2022, 01:24 AM

Windscreen seal okay.

02-03-2022, 01:20 AM	#1
Lozza47 Private First Class 38 Rep 129 Posts Drives: 2013 F30 335i / 2011 E92 M3 Join Date: Sep 2019 Location: Melbourne iTrader: (0)	Intermittent crank but no start - wait a while then starts Hi all, I was driving my 2010 320d through a bad rainstorm and ever sense then, occasionally on cold start, after pressing start, the car will pause for 5 seconds then start cranking endlessly, no start with every single fault warning (drive fault, traction control etc) in the idrive. I then let the car sit for about 30 seconds and the car turns on fine no problem no existing stored codes. I'm unsure how to diagnose what is wrong because the car still seems to work fine it's just intermittently this happens on cold start (being left sitting over night for instance). Previously I've had the dme replaced due to water damage and the mechanic drilled holes in the bottom of the ecu compartment to help drain water. I don't think the ecu is fried because it still occasionally runs no problems at all. Any thoughts? __________________ 2011 E92 M3 - Mineral White - Pure Edition I
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02-08-2022, 11:18 PM	#2
Lozza47 Private First Class 38 Rep 129 Posts Drives: 2013 F30 335i / 2011 E92 M3 Join Date: Sep 2019 Location: Melbourne iTrader: (0)	Just another update, had the DME replaced with a second hand unit and coded in. Everything back to normal. This is the second DME that has failed in this car. There was no sign of water or dirt in the ecu box which is odd. Any suggestions on what else could cause DME failure? __________________ 2011 E92 M3 - Mineral White - Pure Edition I
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02-12-2022, 08:30 AM	#3
Owen81 Lieutenant 83 Rep 432 Posts Drives: 335d, 17/22 TDI Join Date: May 2015 Location: Alberta, Canada iTrader: (0)	Could be a short somewhere else in the system. If you had that much water in your sealed ECU box, how much did other areas see? There is a reason flood cars are written off immediately, it may seem like there is a quick fix but you can experience electrical issues for the remaining life of the car.
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02-12-2022, 07:42 PM	#4
thalastdon1985 Enlisted Member 27 Rep 43 Posts Drives: 2007 328i Join Date: Oct 2018 Location: SC iTrader: (0)	If your windshield has been replaced, it is likely the seal at the bottom isn't secured. It appears to allow water to flow into the dme area. Every e90 I've seen with a water damaged dme has had this condition.
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02-12-2022, 09:18 PM	#5
Lozza47 Private First Class 38 Rep 129 Posts Drives: 2013 F30 335i / 2011 E92 M3 Join Date: Sep 2019 Location: Melbourne iTrader: (0)	Thanks I will check the windshield seal. The first time plenty of water got into the ecu box however this time round there was no signs of water or dirt in the box suggesting dme not have actually been water damaged. I also had the bmw specialist clean the water channels and still a larger drainage hole. The lower steering rack did get quite a bit of water on it but not sure how that could've short it. Any way to diagnose a potential short or is there too much complexity to narrow it down? __________________ 2011 E92 M3 - Mineral White - Pure Edition I
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02-13-2022, 01:24 AM	#6
Lozza47 Private First Class 38 Rep 129 Posts Drives: 2013 F30 335i / 2011 E92 M3 Join Date: Sep 2019 Location: Melbourne iTrader: (0)	Windscreen seal okay. __________________ 2011 E92 M3 - Mineral White - Pure Edition I
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