I am working on a 05 F150 with a 5.4, and I just did timing chains, cam phasers, an oil pump and spark plugs. After putting the truck back together and making sure to burp the cooling system and do an idle relearn, it wen into reduced engine power after about 8 miles of driving. According to my scanner it was running about 210-220, but cooled down to 205ish at idle after coming to a stop. I replaced the thermostat and now it idles at temps between 192 and 199 degrees. The issue now is that when I watch the live data is show the engine calculating a load of 25% at idle and a spark advance of 10-15 degrees. The problem comes when you give it throttle, either in neutral or taking off from a stop. The load just to between 80 and 90% and the spark advance climes to between 38-45°, all at engine speeds below 2000 rpms. It does not show any codes, andidles perfectly smooth. It has good oil pressure and everthing mechanical seems to be fine. I am just stumped as to what is causing the ecu to increase the spark advance to such a degree. Any help would be much appreciated.

 

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I'm not exactly sure what your concern is here. Are you concerned about Engine Load of 25% at idle with spark advance ~ 10-15º? That would be roughly normal for a perfectly smooth idling 5.4L 3valve.

Sounds like you got the temp under control. 80 to 90% load is no real surprise accelerating some (except perhaps in neutral), not accelerating normally from a stop. And 30 to 45 degrees advance would seem normal at 2000 rpms - unless load gets on up around 95-100 where I would expect the PCM to bring it down --- just under detection of any Knock. All sounds pretty good to me.

The PCM handles all advance based on 'hell only knows' what all parameters / metered downward by knock retard. But advance is generally good (giving more power) as long as knock doesn't develop.