15-525 Analyzing oscilloscope image
Operation no. of operation texts and work units or standard texts and flat rates |
Pass image - Parade (engine speeds up to approx. 1000 rpm)
Image selection Parade. Image is extended in horizontal direction.
1152-11720
Pass image - overlap (engine speeds up to approx. 1000 rpm)
Image selection Overlap. Set start and end ignition operation on left and right of calibrated line.
1152-11721
Pass image - Parade (engine speeds above approx. 1000 rpm)
Image selection Parade. Image is extended in horizontal direction.
1152-11718
Pass image - overlap (engine speeds above approx. 1000 rpm)
Image selection Overlap. Set start and end of ignition operation on left and right of calibrated line.
1152-11719
Ignition line commences too high, but at uniform point.
Image selection Overlap.
Visible Idle speed, at one or several cylinders.
1152-11722
Image selection Parade.
Image fault Starting point of ignition line above 1.5 kV.
Visible Idle speed at one or several cylinders.
Cause Excess of ohmic resistance on secondary side as a result of spark plug connector, distributor cap, ignition cable, distributor rotor, or spark plug.
Remedy Replace parts with excessive ohmic resistance (use ohmmeter).
1152-11723
Image selection Parade.
Image fault Starting point of ignition line above 1.5 kV.
Visible Idle speed at all cylinders.
Cause Excessive ohmic resistance on secondary side as a result of distributor rotor, distributor cap or high-voltage cable no. 4 with connector.
Remedy Replace parts with excessive ohmic resistance (use ohmmeter).
1152-11724
Required ignition voltage
Image selection Parade.
Image fault Cylinders 4, 5 and 6 require a higher ignition voltage compared to cylinders 1, 2 and 3 (pay attention to firing order).
Visible Idle speed.
Cause Uneven mixture distribution.
Remedy Test mixture distribution (e.g. fuel quantity comparison measurement 07.3-160).
1153-11717
Image selection Parade.
Image fault Bias line of cylinder 4 too low - ignition line longer,
bias line of cylinder 2 too high - ignition line shorter.
Visible May occur at any engine speed when engine under load or not.
Cause Spark plug of cylinder 4 - electrode gap too small, fuel/air mixture too rich, loss of compression.
Spark plug of cylinder 2 - electrode gap too large, fuel/air mixture too lean, additional spark gap at secondary end.
Remedy Bias line too low: alter spark plug electrode gap to correct setting, test cylinder leaktightness.
Bias line too high: alter spark plug electrode gap to correct setting, check distributor cap, ignition cable and spark plug for interruption (use ohmmeter).
1152-4827/2
Starting point of ignition line jumps
Image selection Parade.
Image fault Starting point of ignition line varies, jumps.
Visible May occur at any engine speed when engine under load or not.
Cause Spark plug coated with carbon, oil, scorched, insulation damage to spark plug connector.
Remedy Clean or replace spark plug, replace spark plug connector.
1152-4825/2
Required ignition voltage, throttle blip load
Image selection Parade.
Image fault Required ignition voltage rises by more than 4 kV.
Visible Repeatedly accelerate engine to approx. 3000 rpm by blipping throttle.
Cause Spark plug electrode gap too large.
Remedy Alter spark plug electrode gap to correct setting, replace spark plug if necessary.
1152-4828/1
Image selection Parade.
Image fault The required ignition voltage increases by more than 4 kV, shortened ignition line, sharp increase in oscillations in opening section above and below zero line.
Visible Start engine after lenghty idle period with oscilloscope connected, accelerate engine repeatedly to approx. 3000 rpm by blipping throttle.
Cause Fuel/air mixture too lean.
Remedy Check injection valve, replace if necessary (07.3-135, 07.3-215).
1152-4828/2
Ignition coil - separate test
pass poor
Image selection Parade.
Image fault Voltage below 20 kV, fewer than 8 voltage peaks.
Cause Winding interrupt, winding short or insulation damage to ground
Remedy Replace ignition coil.
Note Not in excess of 28 kV otherwise ignition coil will suffer premature damage.
1153-4832/6
1152-4832/5