My Key Less works only 9 times out of 10.
Because once in a while, this happens;

The starting motor (or what you call it) starts off perfectly, but after just 1 second, it gives in just before the engine is about to start!
So then, I'll push the button again, and HOPEFULLY this time it continues so long, that the engine has time to start up...
But worst case scenario sofar is, I had to do this 4 times in a row before the engine actually started!

I should also mention, that it doesn't make any difference if I hold the button during the starting procedure or not.

Btw, this is my 5th Key Less car, and I have never experienced this before!
So I guess it's not common.

But am grateful for any thoughts!
Thanks.

 

When the engine begins to crank then "aborts" this is usually caused by lack of lubrication of the ring gear which allows a voltage spike to trick the crank position sensor to think the engine has already started so the starter is disengaged. Sounds weird and long winded but it's a problem that is rarely seen anymore, it was common when the M112/113 were new.

Get your dealer to apply some grease to the ring gear and see how that goes for you. Part number of the required grease A000 989 76 51 (1kg tub), your dealer should have some in workshop supplies.

 

Sounds very possible, because there's like a jamming noise. Like a disc or something isn't rotating very easily...
And there is also a squeeking sound (like the sound of lack of lubrication)!!!

Where is this ring located..? And what does it do..?

 

The ring gear is the gear that the starter motor engages with. It's like the gear on the end of a flywheel, but for an auto it's called a flex plate.

I now realise you're talking about a V12, you probably should get the dealer to look at it especialy if there is a noise, the ring gear lube problem rarely has a noise assosiated with it.

I'm half thinking that since yours is modified you may have cracked the flex plate. I've seen this heaps on 5 cyl diesel sprinters but it's not common to other engines. With the additional power it is under much higher loads since this is what links the engine to the transmission..........just what's in the back of my head now you've said it's noisy as well.

Let me know how it goes.