Traded our 2014 XLT Eco Boost screw in on a 2015 Lariat screw with the 5.0 V-8. Here it is 50-55 f. at this time on a cold start the Eco would idle down to normal idle from fast idle in park in 2 minutes or so. The new ( has 160 miles now ) 5.0 does not come down from fast idle to normal idle in park at all till I just give up after 5-10 minutes and just drive off. I just give up as know it is a waste of gas to wait over the 2 minutes. . In a mile down the road at 4 way stop I can put in neutral and will be at normal slow idle. Is this normal for the 5.0 ? We are very happy with this new one but maybe trip to dealer .
Any thoughts or did I miss this problem in many searches on the forum.

 

Doesn't sound right but why are you letting it idle for 5-10 minutes?

Start it up, wait a few seconds and then drive it away.

 

It is very new. That engine may have never even seen colder ambient temps coupled with colder coolant temps yet so it is running on base maps which will favor higher rpms to prevent stalling. The PCM probably still has to "learn" some of the fuel tables for certain temps ect... If it still does this after a few weeks I would be a little more concerned.

How fast an Idle are we talking after 5 minutes?

 

I was just curious if it would ever go down from fast idle. So I waited and it did not till down the road. Fast idle is about 1250 with Torque app. I will wait a week and see how it goes.

 

If you have the AC or HEAT on, that along with the engine trying to warm up may keep it a high idle for an extended period of time. Probably all in the software, when it's hot and humid in the summer the electric fan comes on with a roar, all in the program.

Normal

 

az mornings are like 35f right now and my 2015 5.0 is doing a similar thing, never really thought much into it, once its warmer in the day, has no issues

 

I was wondering the same thing. I've had my 2015 5.0 for about a week and half and have notice some high idling. It does tend to happen when it's cold/cooler outside. I hope that is normal as some have said. It will be difficult to tell as we are heading into winter and it's only getting colder. I'll have wait about 6 months to see if it stops.

 

Does it seem to jerk on take offs or is it just me.

 

That doesn't sound correct. Mine will drop down to 1000 rpm's after 1 to 2 minutes depending on outside temperature. We are just starting to be in 40F in the morning, so I'm not sure about lower then 50F.

 

It was 20 degrees yesterday morning and mine idled fast for quite a while also (after remote starting it). Sounds like it's normal. I think it's an emission thing because the fast idle heats up the converter quicker which equals cleaner exhaust.