Checking ignition timing.
- On the back of the center spark plug cover is a timing loop. On the R34 its blue.
- Connect timing light to loop. Direction of the loop is important. If the readings seem 40 degrees off, flip the loop over.
- Disconnect IACV-AAC valve harness to cancel idle speed and ignition timing feedback controls
- With engine idling check ignition timing.
- Base timing is 20 deg BTDC
- 0 is the orange mark on the factory damper. 30 is the last mark. The lines are every 5 deg.
- If the timing needs to be adjusted. Loosen the three 10mm bolts on the cam/crank sensor.
- Clockwise - Retards ignition timing
- Counterclockwise - Advances ignition timing
- 20 deg BTDC should be about in the center of the range of the cam/crank sensor with stock cam gears. If its at some extreme, you probably did something wrong.
