So have seen some suggest that the ecoboost engine should idle for a while after driving before shut down. The manual suggests letting all engines idles for 3-5 minutes with more time the larger the engine. However with the auto shut off feature it seems the engine is turning itself off constantly in traffic so it seems these two things are in conflict with each other. Someone on this group probably has a rational answer. I hate auto shut off btw, but that is another topic

 

Years ago turbos needed idle time to cool down after being run hard so you wouldn't cook the oil in the bearings. Today's turbos have coolant flowing through them to remove the heat.

 

If you are in tow/haul mode the auto shutoff is disabled, same with Sport mode.
I read somewhere that ecoboost engines will passively move coolant through the turbos after turning off the engine and that this is sufficient to prevent heat soak. That said I always idle my 2.7 for at least a couple minutes after I tow my ~7000lbs loaded travel trailer, no point taking any chances!

Edit - found the following Ford quote at http://ophelia.sdsu.edu:8080/ford/06...ost-29657.html

“The EcoBoost engine uses passive thermal siphoning for water cooling,” Plagens explains. “During normal engine operation, the engine’s water pump cycles coolant through the center bearing. After engine shutdown renders the water pump inactive, the coolant flow reverses. Coolant heats up and flows away from the turbocharger water jacket, pulling fresh, cool coolant in behind. This highly effective coolant process is completely silent to the driver, continuing to protect the turbocharger.”

 

Thanks to ejk905 for posting that nice read about the turbos!

 

If you really work the snot out of any engine, then a few minutes cool off is a good idea. Otherwise no, and the above mentioned about modern turbos is spot on.

 

While coking is no longer an issue, if you were running your turbos (or engine) hard, it's always a good idea to let it idle long enough for the temperatures of the various metals to equalize before shut down. It takes very little time to do this, 30 seconds max. Hot shutdowns can be particularly hard on exhaust plumbing.

 

Have 166k on a 2011 3.5. I cool it for a minute or so before shutdown if not run lightly loaded in the last few minutes.

All I can add is the engine hasn’t broken an exhaust stud nor cracked a manifold,*yet*.

 

I cant imagine there are a ton of situations Where you could push the truck hard and then immediately pull over and shut it off before stuff cools. Even when my truck gets up i to the 240’s, the temps come right bacl down after 20 seconds or so of lifting off the throttle. And the only time you would be railing on the truck so hard that it gets that hot is at freeway speeds so you are not slowing down and shutting it off that fast.