My Ecoboost overheats too! I exhibit the same behavior as coolzzy on long steep grades with my foot in the gas.
I just took my 2017 Limited Expedition EL on the first big test up the IKE Guantlet. I drove from Frederick CO, through Denver then up over I-70, then down to Silverthorne. I had my 4 kids in the expedition, dog, and the trailer had a moderate amount of camping gear. I didn't weigh it this time but it was likely around 6500lbs in the trailer + our passengers/dog (750lbs).
The only time I experienced overheating was coming from the Denver side which is backwards from what you'd see in the youtube/IKE tests that TFLTruck performs. From the Denver side you end up climbing at 6-7% grades, you have some steep down hill runs, then some flat or gradual runs, and some really steep 6-7% runs. Overall though, coming from Denver side heading west, you experience a lot longer pulls. It's a harder test than what those youtube guys do...at least for engine temps.
I received the overheating/dash warning for the engine temperature when I had my foot about half way in to the throttle, the engine seemed to be handling the load just fine, it just must not have adequate cooling to handle the sustained grade. I will admit though, I was probably doing 65mph or a hair more when the light came on, and I had been going up a very long grade not giving the engine much break at all, once I backed off the throttle a bit, dropped it to about 55mph, it started to cool down. The gauge showed the temp around 3/4 of the way up, not in the red yet, once letting off the gas, it began to drop slowly. It took about 30 seconds to a minute or so come back down to reasonable mid range on the gauge. Once back to normal, I didn't have the issue again and just kept it around 60-65mph. If I hit a really steep long grade, I just watch the engine temp gauge, if it started to creep up, I'd slow down to 55 or 60 and it seemed to hold there.
On a side note, the ecoboost pulled the IKE gauntlet very easily compared to my old 8.1L vortec. It also pulled much better than the 2017 Sequoia I had....gotta love those turbos at high elevation.
I was thinking I could probably add a larger radiator, or maybe a lower temp thermostat, but honestly I probably shouldn't be doing more than 60mph up that pass anyway, so I'll just go a hair slower in a few spots to keep the temp down. I don't ever see much worse temperatures or grades than I do here in Colorado.
The only area that it didn't perform well was with the rear end wiggle. Compared to my old 3/4 ton Yukon it wiggles a lot with wind/semis, but it still wiggles a lot less than my Sequoia did. It was manageable, just not great with the wiggle. I have my WDH and 4 point anti sway setup pretty well, lots of end bar weight for the sway control, and I increased my rear tire pressure to almost max.
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