Startup Stumble

[s2ms]

The last 4 times I've cold started my 2017 it fires up normally to a fast idle, then almost immediately stumbles for a moment, then recovers back to fast idle. Hopefully the video shows what I mean, although wasn't so bad that time, a couple times it almost died before recovering. Afterwards it runs perfectly fine, no problems. I did pull the MAF sensor which had a little dirt so cleaned it anyway but that had no effect on the issue. Noticed when I turn the ignition on the battery is at about 11.5V then quickly rises to about 14.2V after starting. If I turn the car off after driving and warmed up it will start normally, no stumble, but the battery again drops to about 11.5V. It seems to me the battery is not holding a charge, could the cold start stumble also be related to a failing battery? The battery was put in the car by the dealer before I bought it new so is close to 5 years old.

Thanks

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[mech94]

my 5 year old battery died 2 months ago I would go ahead and throw a new one on there but my 2017 does the same thing after sitting for a few days I don't pay any mind to it

 

[s2ms]

Thanks. This is a new development, until now the car cold started perfectly no matter if it was sitting for 1 day or a month.

 

[dtheo]

Mine does same thing, car runs fine, I have not looked at voltage or oil pressure though, oil pressure is the life and death of engines.

 

[brokenblinker]

+1 - mine does it and has even after replacing the battery and it cranking much harder. Has done it as long as I've owned it with no meaningful outcomes (8K miles since I bought)

 

[s2ms]

Just to update this....ended up replacing the battery anyway since it was almost 5 years old and already on borrowed time. The new battery seems to have solved the stumble so it appears something wasn't happy at cold start with the lower battery voltage.

Is the stumble an early indicator of a failing battery? Who knows, but seems like it was in my case.

 

[Angrey]

Just to update this....ended up replacing the battery anyway since it was almost 5 years old and already on borrowed time. The new battery seems to have solved the stumble so it appears something wasn't happy at cold start with the lower battery voltage.

Is the stumble an early indicator of a failing battery? Who knows, but seems like it was in my case.

It's the EPA's dumbass fuel economy stuff. So Ford (and others) create all sorts of brain damage with the charging system to that it reduces parasitic draw when the battery doesn't need charging (or at lower rpms and loads) and only tasks the full alternator output when the battery needs charging. I think at start up it's problematic because the charging strategy is trying to remain dormant until the car idles down, but if the battery is weak, it then makes it grumpy.

The charging system should honestly be, full charge unless WOT condition. Simple.

The same issue is revealing itself with daytime running lights. The EPA's stranglehold causes manufacturers to try to squeeze every single ounce, so when people run their DRL's, they don't realize that the rear running lights aren't on. (they only come on when you turn the full headlights on). The result is a growing number of oblivious people running around at night not realizing they're tail lights are out (because their DRL's are on and they aren't aware the full headlights are brighter and turn on the rears). You run up on a LOT of people now who have no running lights on in the rear in the dark. Why? Because to save power/parasitic draw on the battery/charging system, they chose to leave the running lights off during the day. Canada is changing this, I'm sure NHTSA and the US aren't far behind.

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