Rough cold start

[AJB0009]

2012 Ford Fusion, 2.5L, 140k miles.
Car has been great, I haven't really done anything to it other than preventative maintenance.
It recently started running rough when first started cold after sitting overnight.
Normally it would start at, say, 1,500 RPM's and slowly come down as it would warm up.
Now, it will start at maybe 1,100 and be kind of rough for maybe 5-10 seconds, then it will work it's way up to 1,500 and smooth out. That's it, everything is normal after that. No drop in fuel mileage or anything else. No check engine light (it has never came on).
I always run either Exxon Supreme 93 or Citgo non-ethanol 90 for fuel.
Any thoughts on what may be the root cause of this issue?
TIA

 

[LazyDog]

Might be time for a new temperature sensor, take a scanner under live data see what it reads when cold. Cold temperature has to be very close to ambient temperature.

 

[michaelluscher]

Has it had the throttle body replaced, PCM reflashed, or both?

Check the CHT sensor connector for corrosion?

VC gasket leaking into plug wells? (Pull coils to check)

When's the last time it had plugs, and what kind?

Any history on the canister purge valve?

 

[Lubener]

If you have to add coolant periodically, minor head gasket seepage into a cylinder is a remote possibility.

 

[01rangerxl]

Might be time for a new temperature sensor, take a scanner under live data see what it reads when cold. Cold temperature has to be very close to ambient temperature.

Yep, just firing the parts cannon here, but an air charge temperature sensor (on the air intake duct) cleared a rough starting problem right up on my Explorer.

Or are you talking about a coolant temp sensor? In either case, make sure your temp sensor readings make sense...

 

[AJB0009]

Has it had the throttle body replaced, PCM reflashed, or both?

Check the CHT sensor connector for corrosion?

VC gasket leaking into plug wells? (Pull coils to check)

When's the last time it had plugs, and what kind?

Any history on the canister purge valve?

I replaced the plugs with OEM Motorcraft at about 75k miles. The ones that I took out looked like new yet. I changed them anyhow.
That's a good point to check that CHT sensor connector. I think that it is a known issue on these from time to time.
Something with the canister was fixed under a recall. I don't remember specifics right now off the top of my head what it was.

 

[AJB0009]

Yep, just firing the parts cannon here, but an air charge temperature sensor (on the air intake duct) cleared a rough starting problem right up on my Explorer.

Or are you talking about a coolant temp sensor? In either case, make sure your temp sensor readings make sense...

Did you just hose it down with some mass air flow sensor cleaner?

 

[01rangerxl]

Did you just hose it down with some mass air flow sensor cleaner?

Since it was 24 years old and a new Motorcraft sensor was $45 and readily available, I just replaced it. I think the design had been revised too because the new one had a longer sensor wire or whatever it's called.

 

[AJB0009]

Has it had the throttle body replaced, PCM reflashed, or both?

Check the CHT sensor connector for corrosion?

VC gasket leaking into plug wells? (Pull coils to check)

When's the last time it had plugs, and what kind?

Any history on the canister purge valve?

Oops, I missed answering your first question. I bought the car when it was two years old and had 24k miles on it. Nothing has been done with the throttle body or PCM since I’ve had it.
Actually, the throttle body was the first thing that came to my mind. I didn’t say that, I wanted to wait and see what everyone else said first.
Maybe it’s just dirty? I don’t know if that would just effect the first 5-10 seconds of idle after a cold start though; and then be fine after that.
I was thinking of pulling it off, cleaning it, and then clearing the PCM memory, so that it has to re-learn idle.

 

[zrxkawboy]

^^^good place to start

 

[michaelluscher]

Ford Issues Extended Warranty to Cover Throttle Body Assemblies

Ford has agreed to issue an extended warranty to cover throttle body assemblies. The program extends the coverage of the throttle body to 10 years of service or 150,000 miles from the warranty start date of the vehicle.

www.ncconsumer.org

If your still within 10y/150k from the in service date, unplug the throttle body, wait for a CEL/Wrench light, and go get yourself a new one + PCM reflash done free of charge

I just bought a 2010 Milan used that this had expired, so I had to buy a new TB from Ford

It's not horrifically expensive or difficult to swap, it's just if they're gonna own up to a problem, let them pay for it

Then go from there

 

[AJB0009]

Update (late):
I have a decent relationship with a local dealer; I get a good wholesale discount on parts, etc. I chatted with the service manager, who was quite knowledgeable. He said that he would take a look at it for me. I let it sit there overnight. He had his best A tech look at it for me. No codes or history. He didn't think that it was bad or out of the ordinary for age and mileage. And really, it probably wasn't, I just knew that it was different, and I'm pretty fussy about such things.
I was going to pull the TB and clean it. They sold me a brand new, OEM TB for like fifty or sixty bucks, IIRC. I know that it was less than $60 including tax. (I still don't understand how it was that cheap). I installed the new TB and flashed the PCM. No real change.
I just pondered the situation a bit. I was then reading on here a thread about HEGOS and folks changing them as preventative maintenance and seeing improvements in mileage, drivability, etc. That sounded like something good to try. I bought it OEM. It was more spendy, I want to say I gave about $125 for it, IIRC. Installed it and flashed the PCM again.
That was it. Instantly returned to a nice, smooth start up.
Unfortunately, I didn't notice any significant mileage improvement.