Post by s54smg2 on Mar 2, 2014 0:11:58 GMT -5
Direct Fire Bosch Ignition Coil
How the BMW direct fire ignition system works:
All BMW 6 and 8 cylinder engines after 1992 use a single coil which is mounted directly over each spark plug. This design eliminates the needs for ignition wires, distributor caps, rotors and the mechanisms to drive these components. Timing and spark sequence is all computer concabbage patch kided. Reliability is increased due to elimination of these components. Having one coil for each cylinder eliminates a no run situation due to coil failure, since all 6 or 8 coils would need to fail at the same time. This also requires each coil to fire only once per two revolutions, rather than a single coil firing all eight cylinders.
On the older BMW models using the single coil ignition system a failed coil typically left you stopped on the road. On a BMW direct fire multi-coil system a failed coil will still allow you to drive the vehicle on the remaining functioning cylinders.
BMW M3 e46 Coil failure Symptoms:
Engine will have sporadic or permanent cylinder miss fire on one or multiple cylinders. This will be accompanied by a C.E.L. check engine light. At idle engine will feel rough, idle poorly and have a lack of power.
Your BMW may also experience abrupt jerking during acceleration. In many cases the miss fire will occur only after the engines warms up. Early stages will be periodic miss fire sometimes after extended driving sessions.
How to check which coil is bad:
Performing this field test can only be accomplished when the coil is not functioning, or miss firing. With plastic trim cover removed from the cylinder head. Before stating the engine locate all the coils and release the hold down clips for each coils signal wire plug. Make sure you leave the signal wire plug connected to the coil. Now with the Engine idling, Start with coil number one, in the case of the V8 models select a forward coil on one bank of the V8. Visually and also by place your hand gently on the intake manifold feel and remember the shack or uneven running.
With a gloved hand or insulated pliers, engine idling gently unplug the signal wire plug. If the engine begins running worst then that coil is functioning correctly. Continue testing all coils in this fashion until you find the coil that make no difference when it is unplugged. If you disconnect the coil and there is no change, then that coil is not functioning. Now that you have located the suspected defective coil turn off the engine, remove the bad coil and switch it with a known functioning coil from another location.
Restart the engine see if the miss fire has moved to the new location. If you are replacing only one coil you may do so at this time. However if the vehicle has extremely high mileage you may consider doing them as a set.
BMP Design
How the BMW direct fire ignition system works:
All BMW 6 and 8 cylinder engines after 1992 use a single coil which is mounted directly over each spark plug. This design eliminates the needs for ignition wires, distributor caps, rotors and the mechanisms to drive these components. Timing and spark sequence is all computer concabbage patch kided. Reliability is increased due to elimination of these components. Having one coil for each cylinder eliminates a no run situation due to coil failure, since all 6 or 8 coils would need to fail at the same time. This also requires each coil to fire only once per two revolutions, rather than a single coil firing all eight cylinders.
On the older BMW models using the single coil ignition system a failed coil typically left you stopped on the road. On a BMW direct fire multi-coil system a failed coil will still allow you to drive the vehicle on the remaining functioning cylinders.
BMW M3 e46 Coil failure Symptoms:
Engine will have sporadic or permanent cylinder miss fire on one or multiple cylinders. This will be accompanied by a C.E.L. check engine light. At idle engine will feel rough, idle poorly and have a lack of power.
Your BMW may also experience abrupt jerking during acceleration. In many cases the miss fire will occur only after the engines warms up. Early stages will be periodic miss fire sometimes after extended driving sessions.
How to check which coil is bad:
Performing this field test can only be accomplished when the coil is not functioning, or miss firing. With plastic trim cover removed from the cylinder head. Before stating the engine locate all the coils and release the hold down clips for each coils signal wire plug. Make sure you leave the signal wire plug connected to the coil. Now with the Engine idling, Start with coil number one, in the case of the V8 models select a forward coil on one bank of the V8. Visually and also by place your hand gently on the intake manifold feel and remember the shack or uneven running.
With a gloved hand or insulated pliers, engine idling gently unplug the signal wire plug. If the engine begins running worst then that coil is functioning correctly. Continue testing all coils in this fashion until you find the coil that make no difference when it is unplugged. If you disconnect the coil and there is no change, then that coil is not functioning. Now that you have located the suspected defective coil turn off the engine, remove the bad coil and switch it with a known functioning coil from another location.
Restart the engine see if the miss fire has moved to the new location. If you are replacing only one coil you may do so at this time. However if the vehicle has extremely high mileage you may consider doing them as a set.
BMP Design