Has anyone out there ever measured the difference in mpg between 0 degrees and 4-6 degrees. Mine was at 6 and I was using a lot of fuel. Thanks for the time.

Ryan

 

That timing wasn't too far advanced, usually it gives better mileage at 4-6*, unless the engine is spark knocking. It might be worth a 1mpg.
Make sure the egr system works, tune up parts are good, & the engine gets up to proper temp (190-200) going down the road. Is the check engine light on?

 

Everything is in totally fresh tune. It was spark knocking ever so slightly at that degree range. Mostly in overdrive under strain going up a hill. It also idled not as smooth and low as I would like. Check engine light is not on. Vacuum is steady and the engine runs strong.

 

The knock sensor will pull timing--reducing power and fuel economy--long before you HEAR spark knock.

Put a scan tool on that thing--I bet you see the knock sensor is active at highway speed.

Your fuel economy may IMPROVE with less timing--if it keeps the knock sensor happy.