There is a coil per cylinder. Petrol engines
- 4 & 6 cylinder 2001 – 2006
- 3 Series E46 1999 – 2006 (incl. M3 E46)
- 3 Series E90
- X3 2004 – 2006
- X5 E53
- Z4 2005 – 2008
- 525, 530 E39 2002 – 2005
- 745, 750 E65 V8 & V12
Symptoms of failure:
- Car “shakes” on idle (rough idle) – customer complaint
- Engine will have a intermittent or permanent misfire on one or multiple cylinders
- Engine light on
- Lack of power
- Jerking on acceleration – when engine warmed up
How it works:
On the older cars using the single coil ignition system a failed coil would have you break down. On the recent models direct fire multi-coil system a failed coil will still allow you to drive the vehicle on the remaining functioning cylinders.
Each cylinder has its own coil mounted above each spark plug. What it does is convert the batteries 12 volts to the thousands of volts needed to spark the spark plugs. Coils have eliminated the need for ignition wires, distributor caps & rotors etc. Everything is now electronically controlled and therefore more reliable.
- One or two coils fail at a time – seldom all at once
- Can be changed in under an hour while you wait (anytime before 12) no need to book.