Naughty! Crank position sensor fail

[PetrolHeadPete]

Driving along close to home last week. Out of nowhere engine did a massive cough and splutter but recovered immediately. Heart in mouth!...drove on (was about 2 mins from home). Then, it coughed and died...engine fizzled out and I had to coast into a side road. Would not re-start.

Recovered to home and this morning I re-tested and still not firing up. I swapped to an old crank position sensor on a hunch...bingo.
Old one measures OK but the end has been slowly filed down by the starter ring teeth and presumably now doesnt make a big enough signal.

Ho hum!

[nawarne]

....Good hunch/detective work!

In fairness, the EvoOli MBE software on the Speed 6 pages would have told you that the crank position sensor had failed, rather than an educated guess .

Did the sensor that came out show witness marks that it had been touching?

Nick

[Madwud]

Out of interest, do people find crank, fuel, oxygen air/coolant temp etc. sensors failing regularly on S6s?

[PetrolHeadPete]

nawarne said:

Did the sensor that came out show witness marks that it had been touching?

Nick

It did yes, the end had been worn off a bit (perhaps 1mm max but obviously enough to stop it working)

What I didnt share on the first post was that where I conked out was, lets say, awkward! So I moved the car very carefully forward up a mild incline for about 1m on the starter with lots of clutch slipping to avoid over-loading it...but without warning it totally died! No clicking or anything so i'm guessing the solenoid jammed. So no cranking either after this little fiasco. Bad situation worse (but at least I was out of the middle of the side road!)
Anyway, new M5 starter for 80quid, took under an hour to swap, and now starts with renewed zing. So lession learnt!