Burning Smell? Pre ignition

I have a 2004 TD4 and i am getting a burning smell (like clutch). It isn't the clutch as i have tested and found out that on pre ignition the smell is present - so it is electrical. The engine is cold so it i am thinking it could be reversed polarity? however i haven't touched any of the sensors.

Thanks

Without the benefit of smell o vision......

It smells like the clutch? But isnt!

For clarity

Do you notice this smell only when glow plugs are lit and before you actually start the engine or once the cold engine has started?

Whenever i go onto preignition the smell comes up - it is strongest near the fuel rail sensor (above the flywheel). Ive disconnected that to see if the smell went but it was still there.

It varies in strength and occurs while driving to - sometimes coming into the cabin and smelt up to 15m away, othertimes have to get right close to the top of the engine to smell it.

Ive pulled out my synergy unit to check if it was that but the smell is still present.

Point to note - engine has recently had trouble starting requiring 10 - 15 turns of the starter motor to get going. Still idles fine (hunts a little on the rev counter for a couple of seconds but i believe that is normal). Going to check my hoses to make sure they are on tight as it could be an air leak - could also be related!

Also have Three Amigos popping up!

Any ideas would be appreciated!

Thanks.

I hope the synergy hasnt messed up my ECU...everything was fine before!