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Test #1: IGNITION TIMING
Ignition timing is essentially telling you when the spark plug is being fired in relation to the position of the piston and crankshaft. The value you are used to seeing is a value in degrees. This is angular degrees, not thermal degrees. In the VG30, the base timing (or the timing reference at idle) is 15 degrees. This means the ECU is making the engine fire at 15 degrees BTDC, or Before Top Dead Center (now you may see why I stated "...relation to the position of the piston and crankshaft.") BTDC means that as the piston is in its upward motion on the compression stroke, the plug is being fired when the crankshaft is 15 degrees before the piston reaches top dead center of the cylinder. The object here in setting base timing is to make the ECU and the timing mark on the pulley agree with each other.
Typical timing lights use an inductive pickup to detect when the plug is being fired and when it detects this, it causes a strobe light to fire off. This basic principle allows us to see exactly when the plug is being fired off in relation to the crankshaft position. On the front of the engine is a timing indicator which shows a range of degrees on what looks like a ruler. The values go from 0 to 30, from left to right. On the pulley is a mark that indicates the position of cylinder #1. When the mark is lined up to "0" on the indicator, this means the piston is all the way at the top of the cylinder. Timing lights also require power in order to fire that strobe light off so be sure to connect the power leads as such.
The inductive pickup:
 NOTE:! Using this point as the pickup I have found to be the quickest, most accurate method of hooking up the timing light. There is also a black loop on the PTU harness that is supposed to be used for this, however, I have on a nuimber of occasions seen vary peculiar results - sometimes getting two points of indication on the pulley and sometimes it being so far off you can't even see it. I DO NOT RECOMMEND using the inductive pickup loop on the PTU harness. Try this method first and if it doesn't work at first, wiggle the pickup around a little on the wire. You should get a pulse. If it still doesn't want to behave, you should pull the coil pack out and use a plugwire extension and put the inductive pickup on the high voltage line going to the plug. I simply have seen the inductive loop do way too many weird things to really trust it with something like ignition timing. Once you have everything properly hooked up, point the light at the pulley and observe. This is what you should see.
 NISSAN FACTORY BASE TIMING IS 15 DEGREES BTDC. They also say +/- 2 degrees, but its not hard to get it dead on. To adjust the timing, the CAM ANGLE SENSOR, or CAS for short, it used to adjust the base timing. 
There are three 10mm bolts that hold the CAS in place. Loosen these with the engine off.
Since the engine rotates clockwise (looking at it from this perspective), turning the CAS clockwise will retard the timing whereas turning it counterclockwise advances the timing. Move the CAS in the appropriate direction to adjust the base timing. Of course, the engine must be running to test it and once you have the CAS loose a little, you can start the engine and then begin moving the CAS a little to get the timing mark aligned to 15 degrees.
This process ensures that the timing values in the ignition timing map of the ECU are in fact, correct. As an example, if the timing in the ECU is running 20 degrees at full load, but the CAS is set to 17 degrees of base timing, the ACTUAL timing the system will be running is 22 degrees. All the CAS is for is simply to make the value in the ECU agree with the actual timing being run. The timing light allows you to verify what the ACTUAL timing is because it flashes the light off when the plug REALLY fires and the markings on the pulley allow you to see what the position of the crankshaft REALLY is.
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08:57:18 08/15/04
Re: timing adjustment - 
