Test Point 5 - Ignition System
TEST POINT 5Ignition System
1. Adjust secondary image on oscilloscope. Connect tester leads to supplier's instructions.
Note: If a fault is displayed for all cylinders, it will be in the primary or secondary circuit between the ignition coil and distributor rotor.
If a fault is displayed for only one cylinder, it will be after the distributor rotor.
2. Check distributor cap for damage, dirt and signs of burning.
Resistance: 1 k-ohm
Retaining hooks must engage firmly when installing.
3. Check distributor rotor.
Shielded resistance: 1 k-ohm
Inspect visually for damage and tight fit.
4. Check spark plug connectors for damage and traces of burning.
Shielded resistance: 3 kohms
5. Check ignition coil.
Primary resistance between ter. 1 and 15: 0.4 to 0.7 ohm
Secondary resistance between ter. 1 and 4: 5.0 to 8.7 kohms
Check that plugs are not missing.
If plug is missing or casting compound has run out, replace ignition coil and control unit.
Note: Pull of spark plug connector to avoid ignition testing via spark gap. This could destroy the ignition coil and control unit.
6. Ignition timing is not adjusted. Check ignition timing with engine warm and running at idle speed.
Ignition timing at 800 ± 40 rpm: 3 ± 3° after TDC
87 models onward, with control units 911.618.111.18, 19 and 20
Ignition timing at 880 ± 40 rpm: 3.5 ± 3° before TDC