[SentraSE-R]

Now this discussion has me curious. The timing specs for my 1NZ-FE engine in my xB are 8-12º BTDC at idle. I just started it up, and the Scangauge IGN value stabilizes right in that range. So I now agree IGN does reflect timing BTDC.

So, I recall from the old days that under load, you had to retard your timing, or go to high octane fuel, to avoid detonation and engine damage. It stands to reason that under light load, coasting on the level or slightly downhill, timing could advance significantly, and give us our best mileage.

The 1NZ-FE has variable valve timing allowing a range of 60 degrees relative to crankshaft angle. Is that what allows the ignition timing advance up to 40+º BTDC?