Intermittent no start

75aces

75aces

:
2012 speed3
Has anyone noticed their M5 for a no start or under power start? Not talking about just cold start. It happens randomly for me.
 
Thanks for the reply. I changed the battery last year. The intermittent no start condition doesn't occur when cold. It occurs very randomly. I was thinking it's the spark plugs or ignition system. Since it's not happening all the time, I just decided to try to switch the plugs and valve cover gasket.
 
When it does act up, there is power but it's weak. Other times, I have to crank it a second time for it to start.
 
The starting system should provide a nice strong crank as long as you turn the key. Even if spark plugs are disconnected. So sounds like you have an issue with the starting system (starter, battery, corroded/loose wiring, or an alternator that won't charge the battery)
Again I say test the battery and alternator at a parts store. If the battery is that new then you could be covered under warranty


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You can have a wearing out starter, defective (weak) battery.
Just because you replaced it last year does not mean it can't fail this year, so have it tested.
 
Also;

Undo the battery terminals and thoroughly clean the insides and the battery posts with a wire brush or dedicated battery post/terminal cleaner. Make sure they're good and tight when reinstalling.
 
Thanks for the comments. Just a side note, before replacing the battery, it was showing the same symptoms. I will do as recommended and hopefully it's not the alternator. You would think that the car would go over 150k before failing.
 
It could possibly be that your fuel system is failing to hold adequate pressure when you first turn the key.
 
hibern8r said:
It could possibly be that your fuel system is failing to hold adequate pressure when you first turn the key.
Click to expand...



its his starting system that is weak (or was weak since its been months and he's probably fixed it by now). A starter is an electric motor that does NOT rely on fuel, air, or spark to spin. If you were completely out of gas a good starter will still crank strong.
 
So far, the issue hasn't come back in a few months. Thanks for all the inputs. Keeping a close eye on it.
 
I had 2 separate instances like this on ours: One was corrosion inside the starter cable. Water had seeped past the end lugs, and got inside the copper. After much diagnosis, my mechanic jumpered around that cable, and it worked fine. Once we removed the starter cable and cut the insulation, you could see the corrosion. From the outside view, the cable looked fine.

2nd instance was the transmission linkage...The car would not fully engage Park, so it wouldn't start. It would hold the car fine, but not engage enough to hit the safety switch...eventually I found out I could start in in Neutral.

But I'm in Canada, corrosion is a pain on any car.
 
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