'07 F-550 6.0l rough cold idle

[The Warden]

Hello!

I'm currently sitting in my company's '07 F-550 bus with 118K on the odometer. I started her cold for the first time in a while (I'm an evening driver, so whatever vehicle I end up in usually is already warmed up from a morning run), and was very surprised at how rough she was running for the first 2 to 3 minutes. I don't recall this bus cold-idling so rough before, and our '04 F-550 certainly doesn't run this rough on cold-start. Once she's warmed up, she runs fine.

Were this an IDI or any other diesel I'm accustomed to, I'd immediately suspect the glow plugs (although the indicator light stayed on steady prior to lighting off)... but I know that the 6.0l has some idiosyncrasies albeit I'm not sure what the symptoms are. Anyone have any recommendations on what I should tell the fleet mechanic to look for?

Thanks in advance I'm thankful I don't have to wrench on this myself

 

[dsltech83]

Injectors or FICM voltage low.

 

['94IDITurbo7.3]

something more simple than that. FICM or injectors would cause issues all the time. his issue is more likely stiction. rough idle when cold but runs just fine when warm. cold oil is thick oil. injectors are fired using oild pressure.

 

[dsltech83]

I've seen plenty of ficms with low voltage start and run fine warm but cold starts were darn near impossible.

 

[army-dude77]

Had same issue with my '06 F350 rough idle when cold(using Rotella 5W-40 full synthetic). Spent the $65 on Rev-X and problem disappeared. Stiction is about a sierra oscar bravo... So it could be either stiction or the dreaded FICM low voltage.

 

[sootman73]

May want to check into what oil they are putting in it. should be a synthetic or semi-synthetic 5W40. Using rev-X is highly recommended by all forums i am on and i will run it in my truck when it goes for oil change(even though it starts fine in single digits not plugged in)

Also you can buy an OBDII bluetooth adapter($100) and if you have a smart phone buy the app called Torque($5) and you can read numerous things like FICM voltage. And this is not vehicle specific so it can be used on any vehicle 1996-later.

 

[93_idi_Turbo]

the STC fitting on the back of the HPOP may be leaking it's a fairly common problem with a 6.0 and will cause a rough idle when the motor is cold check into this

 

[79jasper]

Spent the $65 on Rev-X and problem disappeared. Stiction is about a sierra oscar bravo... So it could be either stiction or the dreaded FICM low voltage.

I second that.
I would try the revX or hot shot's secret.