I warmed up the car to the point where the fans were kicking on and off on their own, and checked my timing.

I noticed that while idling with the fans off, the timing was perfectly at the center of the 3 marks. Then I noticed that when the fans kicked on, the idle dropped by about 150 rpm, and the timing advanced about an inch past the group of 3 marks.

Is this normal? My understanding was that the idle is supposed to increase under electrical load? (I've already replaced the ECU, ELD, IACV and alternator while troubleshooting a different problem.)

 

Ignition timing does NOT stay static unless you jump the service-check-connector on your drivers side shock tower (plug under the yellow rubber cover). Yes this is normal. The ELD inside the engine bay fuse box tells the ECU to switch the alternator between one of two different charge settings. When the fan kicks on, it most likely boosts the alternator output which effects the idle and the timing.

 

I had the connector jumped with a thick piece of soldering wire. I must not have had it shoved in there far enough to make a contact.

 

Hmmm. Allegedly jumping that connector is supposed to lock the timing for the purpose of check & adjust. I still wouldn't be surprised if the fan had some effect on timing when it comes on. I would definitely set my base timing when the fan is off. :D