2023 F-150 5.0 random rough starts when warm

[Noah58]

After driving at normal operating temp and then allowing the truck to sit anywhere from 20 minutes to maybe 2 hours it will randomly have a very odd start. It only happens once , then I could shut the truck off and start it right back up normally. I will attach a (poor quality ) audio/video that will maybe help. It seems as if the the is starting very fast like before it’s actually ready , barely hear the starter turn and it’s already running , it will have a shaky idle for a second or two then levels out when this happens. I did order a new starter but haven’t received it yet, hoping that will fix the issue but my hopes are not high. I had it to 2 different dealers and they both said they couldn’t replicate it. This morning while I was looking around trying to find something obvious jump out at me I did notice a hissing and it seems the pcv hose might be leaking at the valve side. Not sure if this could be causing my problem or not but I am going to order a new valve and hose also. I got an obd link and have been checking fuel pressure with FORScan, if anyone has something they think I should check I am all ears .Any input is appreciated.

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[MadMax2995]

Have you found a solution? Having same exact problem on my 18 5.0

 

[Noah58]

Have you found a solution? Having same exact problem on my 18 5.0

No I have not , I changed the crankshaft position sensor a few weeks ago and it still does it , it hasn’t made the Loud noise since I changed the sensor but it still does the like immediate start as soon as I touch the key when it’s hot randomly , if I had to guess the noise will come back. Going to change the camshaft position sensors maybe tomorrow. I also notice a rattle in the oil pan/bell housing area during a hot shut off, not sure where exactly the noise it yet. I’ve had it to 4 dealers and none of them have been willing to put anything more than maybe 20 miles on the truck. I read a guy having what seemed the same issue on a Toyota forum, said he ran some fuel system cleaner through the tank and it mostly took care of it . Maybe worth a shot

 

[JExpedition07]

Starter is likely starting to get a little weaker or has an iffy ground connection, 12:1 compression is fighting near 220 psi of head on 8 bores. These starters have their work cut out for them. Trying to crank a gen 3-4 5.0 over with a breaker bar from the crank nut is an eye opener, insane back pressure.

 

[Noah58]

It is a brand new starter the truck only has 22k on it

 

[Noah58]

Have you found a solution? Having same exact problem on my 18 5.0

Figure anything out ?

 

[MadMax2995]

Figure anything out ?

No I haven’t been able to figure it out. Now that’s it’s getting colder out it seems to be doing it less for some reason. Hasn’t done it to me for a couple days.

 

[Noah58]

No I haven’t been able to figure it out. Now that’s it’s getting colder out it seems to be doing it less for some reason. Hasn’t done it to me for a couple days.

How weird , same here , it’s kinda hot during the day where I’m at, so idk if it’s the cold or if it’s the fuel system cleaner , I doubt it but never know

 

[Noah58]

No I haven’t been able to figure it out. Now that’s it’s getting colder out it seems to be doing it less for some reason. Hasn’t done it to me for a couple days.

Does your truck do the super fast ignition and noise also ? After changed the cps I haven’t had the noise happen anymore just a quick start , which I suppose could be just due to temp

 

[MadMax2995]

Does your truck do the super fast ignition and noise also ? After changed the cps I haven’t had the noise happen anymore just a quick start , which I suppose could be just due to temp

Yeah sometimes I can’t hear the starter doing its job at all. Just starts up and starts rough. What kind of noise do you hear? Mine sounds almost like a pop or a clunk.

 

[Noah58]

Yeah sometimes I can’t hear the starter doing its job at all. Just starts up and starts rough. What kind of noise do you hear? Mine sounds almost like a pop or a clunk.

Yeah I get the same exact thing , I will keep you updated if I figure anything out or if it stops completely , I drive a company truck to work everyday but drive this one when I get home just to try to get it to act up. Will be taking it on a 2k mile trip in a couple weeks so I would imagine if it’s gonna get hot and do it it will be then

 

[Bluegrass]

Something to know that few know.!
The PCM goes into an Emissions test every time the engine is started.
Its testing the CATS for Oxygen storage efficiency.
The Idle RPM goes upward of 1000.+ from cold starts
The Ignition timing goes retarded, the fuel goes richer to prepare for the test that has to bring the CATS TEMPS up from Ambient or whatever their Temp is at that time, to 1200* then back down to about 800*.
This is to measure their health in a specified short time interval.
As this takes place the idle will begin to drop down after a few minutes.
At the beginning it may cause rough idle until the test setting go back to normal.
Good luck.

 

[Noah58]

Bluegrass , I pulled my spark plugs today to see if any were wet just kinda looking for a flood condition , I came across one plug that was very slightly wet and smelled a little like unburnt fuel, I put a bore camera down into that cylinder , the downhill side of the cylinder had a pool of slightly oil colored fuel. Truck started up fine after I got done , checked with the camera again this evening after truck had been sitting for several hours and that cylinder was dry , any input here ?

 

[Bluegrass]

If it's only one cylinder, take a look a few more times to see if it still exists.
If yes, one of the Injectors for that cylinder may be leaking.
On start-ups the port Injector is always used for mixing with incoming airflow for about 15 seconds +/-, then Injection is transferred to the Direct injector and Idle should smooth out.
Good luck.

 

[Noah58]

This was the plug that came out of that cylinder

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