When adjusting the ignition timing, keep hands, equipment and wires at a sufficient distance from the fan impeller.
This section describes the procedure for checking and adjusting ignition timing on engines equipped with TCI. On engines with the Motronic control system, the ignition timing is determined in the electronic control unit and cannot be adjusted. Using the following procedure, the ignition timing can be checked, but no numerical values can be obtained, so if you have any concerns about incorrect ignition timing, contact your BMW dealer.
This procedure requires some special tools. The engine must be at normal operating temperature and air conditioning (if installed) should be turned off. Make sure the idle speed is correct.
Tools for checking and adjusting ignition timing
1 - Vacuum plugs - In most cases, vacuum hoses should be disconnected and plugged. To do this, if desired, you can use plugs of different sizes and shapes
2 - Strobe lamp with induction sensor - Flashes with a bright directional beam of light when the #1 spark plug is fired. Connect the wires according to the attached instructions
3 - Key for the ignition distributor - On some models, the mounting bolt is difficult to reach with conventional keys or socket heads. A similar key should be used
1. Apply the parking brake and block the wheels to prevent the vehicle from moving. Transmission must be in neutral (manual) or in the Parking position (automatic).
2. Ignition timing marks are located on the engine flywheel (they can be seen through the ignition timing hole in the clutch housing) and/or on the vibration damper on the front end of the engine.
3. If the vacuum regulator of an advancing of ignition is applied, then disconnect a vacuum hose from it.
4. Connect the tachometer and strobe lamp in accordance with the manufacturer's instructions (a lamp with an inductive sensor is preferred). Typically, the strobe power wires are connected to the battery terminals, and the sensor wire is connected to the #1 spark plug high voltage wire. Spark plug #1 closest to front of engine.
If a strobe lamp with an induction sensor is not available, do not pierce the spark plug high voltage wire to connect the strobe lamp control wire. If the insulation of the high-voltage wire is damaged, then the voltage of the secondary circuit at the point of damage will close to the housing and the engine will malfunction.
On some models, a TDC transmitter is installed to check the ignition system. However, to use it, a special BMW tester must be connected to the diagnostic socket, so if a special tester is not available, then a regular strobe lamp should be used. Ignition timing marks can be located on the vibration damper, and if there are none, then there should be a TDC mark. If the stroboscopic lamp has an adjustable delay, then the ignition timing can be determined by first zeroing the measurement, and then rotating the adjusting device until the TDC marks are aligned, after which the ignition timing advance value is read from the stroboscopic lamp. If a standard strobe lamp is used, mark the vibration damper according to the required ignition timing advance and use the formula to calculate the distance from the TDC mark to the ignition timing mark:
Distance =
where p = 3.142
r = damper radius
lead = required advance TDC in degrees
5. With the ignition off, loosen the nut of the ignition distributor bracket so that the distributor turns without slipping.
6. Make sure the strobe light wires are clear of the drive belts and fan, then start the engine.
7. Increase the engine speed to the desired value and then point the flashing strobe light at the ignition marks - be very careful with the moving parts of the engine.
8. The mark on the flywheel or vibration damper should appear stationary. If it is aligned with the required mark on the clutch housing or engine front cover, then the ignition timing is correct.
Ignition mark "FROM" on the flywheel.
Ignition mark "OZ" on the flywheel.
9. If the marks are not aligned, then adjustment is required. Rotate the ignition distributor very slowly until the marks line up, being careful not to touch the high voltage wires.
10. Tighten the distributor bracket nut and check the ignition timing again.
11. Stop the engine and disconnect the strobe light and tachometer. Connect the vacuum hose, if available.