How to test and replace ignition coils on BMW 325?

Ignition Coils

First refer testing instructions,if its test faulty,then go through replacing procedure for ignition coils:---

Testing

E36 Models
Except M44 Engine

Fig. Removing the coil pack cover-M42 engine shown

Fig. Coil pack cylinder assignments-M42 engine shown

1. Refer to the spark plug removal procedures in Section 1 and remove the valve cover trim cover. On M42 engines, remove the coil pack cover.
2. With the ignition OFF , disconnect the harness connector by releasing the locking bar and pulling off the connector.
3. Check the primary resistance between the two outside terminals (terminals 1 and 15) of the coil connector socket.
4. The resistance should be approximately 0.4-0.8 ohms. Replace the coil if out of specification. The secondary side of the coil cannot be checked due to the design of the coil.

M44 Engine

The M44 engine uses a combined ignition coil assembly. The coil assembly is comprised of four separate ignition coils.

1. With the ignition OFF , disconnect the harness from the ignition coil assembly by turning the knurled electrical connector counterclockwise and carefully pulling off the connector.
2. Refer to the illustration of the primary electrical connector and check the primary resistance between the terminals for each individual coil (terminals 1 and 15) as follows:
   
   
   Coil 1: Pin 1-Pin 2

   Coil 2: Pin 6-Pin 2

   Coil 3: Pin 7-Pin 2

   Coil 4: Pin 5-Pin 2
3. The resistance should be approximately 0.4-0.8 ohms. Replace the coil assembly if out of specification. The secondary side of the coil cannot be checked due to the design of the coil.

Fig. Use an ohmmeter to check the resistance between the specified pins

Fig. The terminal pins are numbered, but difficult to see. An enhanced photo really helps. Note the absence of a pin terminal 4

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Removal & Installation

E36 Models
6- Cylinder Engines

Please refer to the spark plug removal procedures in Section 1 for details pertaining to individual ignition coil removal.

M42 Engines

1. With the ignition OFF , remove the ignition coil cover.
2. Label the wiring to ensure proper reassembly.
3. Detach the harness connector by releasing the locking bar and pulling off the connector.
4. Remove the high tension wires from the ignition coil(s).
5. Remove the ignition coil mounting fasteners, then remove the coils.
6. Installation is the reverse of the removal procedure.

M44 Engines

The M44 engine uses a combined ignition coil assembly. The coil assembly is comprised of four separate ignition coils and is replaced as a unit.

1. With the ignition OFF , disconnect the harness from the ignition coil assembly by turning the knurled electrical connector counterclockwise and carefully pulling off the connector.
2. Remove the ignition coil bracket mounting fasteners and remove the combined coil assembly.
3. Remove the combined coil cover.
4. Remove the high tension wires from the ignition coil(s).
5. Installation is the reverse of the removal procedure.

Fig. The wiring harness is removed by turning the electrical connector lock-ring counterclockwise

Fig. Once the combined ignition coil cover is removed, the high tension wires can be disconnected

Fig. Make sure to label the plug wires before removal

Fig. Clean the grounding contact and mounting bracket of the coil pack with a wire brush before installing

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For more car related problem troubleshooting:---

This are the sections, you can go through and click the link to read its troubleshooting.

---------

The car will not start?

http://schematicsdiagram.blogspot.com/2011/06/car-will-not-start.html

-----------------

Car will not crank?

http://schematicsdiagram.blogspot.com/2011/06/car-will-not-crank.html

-----------

Car has no spark?

http://schematicsdiagram.blogspot.com/2011/06/car-has-no-spark.html

-------------

How to troubleshoot car battery?

http://schematicsdiagram.blogspot.com/2011/06/how-to-troubleshoot-car-battery.html

-----------------

How to test starter solenoid?

http://schematicsdiagram.blogspot.com/2011/06/how-to-test-starter-solenoid.html

--------------------

How to test cars starter?

http://schematicsdiagram.blogspot.com/2011/06/how-to-test-cars-starter.html

How to replace starter in car?

http://schematicsdiagram.blogspot.com/2011/06/how-to-replace-starter-in-car.html

-----------

car will turn over but will not start?

http://technoanswers.blogspot.com/2011/05/car-will-turn-over-but-will-not-start.html

-----------------

Car wont start?

http://howtobyme.blogspot.com/2011/10/car-wont-start.html

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How does distributorless ignition system works on BMW 325?

General Information

Beginning with the introduction to North America in 1992 of the E36 chassis/platform, the Double Overhead Camshaft 4-cylinder M42 and 6-cylinder M50 engines found in the 3 Series vehicles have been equipped with a distributorless ignition system. The ignition timing and ignition advance are controlled by the Powertrain Control Module (PCM) to match the driving, fuel and atmospheric conditions. The PCM optimizes the ignition timing using input from a collection of sensors. The ignition timing can be checked for diagnostic purposes, although it cannot be adjusted. The distributorless ignition system uses one ignition coil per cylinder, unlike the distributor type system that has one ignition coil for the entire system and uses a distributor to dispense the high-voltage ignition to the spark plugs.

The distributorless ignition system, which uses individual ignition coils, operates on the same principle as those on the distributor-equipped engines. However, instead of the distributor's rotation being used to distribute the spark from the ignition coil, the PCM controls the switching of the current through the primary windings for each of the individual ignition coils. When current to the ignition coil is stopped, a high voltage current flows directly from the ignition coil to the spark plug.

The PCM contains the memory for basic ignition timing for different engine speeds and manifold airflow rates. The PCM also adjusts the ignition timing according to engine coolant temperature. The Cylinder Position (CKP) sensor is used by the PCM to monitor the crankshaft speed. A misfire can be detected by the PCM if the crankshaft speed fluctuates.

The following sensors are used by the PCM for ignition timing control:

Top Dead Center (TDC) sensors. These two sensors, TDC1 and TDC2, determine ignition timing during start up and when the crank angle is abnormal

Cylinder Position (CKP) sensor. This sensor detects engine speed

Manifold Absolute Pressure (MAP) sensor. This sensor detects the intake manifold air volume

Engine Coolant Temperature (ECT) sensor. This sensor monitors the engine coolant temperature

Knock Sensor (KS). This sensor allows the PCM to adjust ignition timing for the octane rating of the gasoline being used

Information pertaining to these sensors is covered in more detail in Section 4 of this manual.

Fig. The distributorless ignition system uses a separate ignition coil for each cylinder. The coil packs are located under a trim cover-M50 engine shown

------------

For more car related problem troubleshooting:---

This are the sections, you can go through and click the link to read its troubleshooting.

---------

The car will not start?

http://schematicsdiagram.blogspot.com/2011/06/car-will-not-start.html

-----------------

Car will not crank?

http://schematicsdiagram.blogspot.com/2011/06/car-will-not-crank.html

-----------

Car has no spark?

http://schematicsdiagram.blogspot.com/2011/06/car-has-no-spark.html

-------------

How to troubleshoot car battery?

http://schematicsdiagram.blogspot.com/2011/06/how-to-troubleshoot-car-battery.html

-----------------

How to test starter solenoid?

http://schematicsdiagram.blogspot.com/2011/06/how-to-test-starter-solenoid.html

--------------------

How to test cars starter?

http://schematicsdiagram.blogspot.com/2011/06/how-to-test-cars-starter.html

How to replace starter in car?

http://schematicsdiagram.blogspot.com/2011/06/how-to-replace-starter-in-car.html

-----------

car will turn over but will not start?

http://technoanswers.blogspot.com/2011/05/car-will-turn-over-but-will-not-start.html

-----------------

Car wont start?

http://howtobyme.blogspot.com/2011/10/car-wont-start.html

----------