Low RPM idle on 2008 4L 6 cylinder

[JWX109]

Low RPM idle on 2008 4L 6 cylinder.

Generally under 1k, making the engine shudder.

thoughts on why?

 

[Todd Z]

Its supposed to idle 750...… there are a thousand questions we can ask.... Last tune up? Plugs AND wires and ALL filters, Good oil change schedule?
Have to check for bad gas, Intake leaks, Vacuum leaks and all sorts of stuff. ANY noises or check engine lights??? Could even be bad timing chains...

 

[JWX109]

its idling around 600.
tune up was a month ago.
plugs and wires and coil changed within the month.
all Filters clean.
Oil change at regular intervals.
Gas is fine.
Had some mis-fire codes recently, since the tune up haven't had them since.

 

[OFFKILTER]

Low RPM idle on 2008 4L 6 cylinder.

Generally under 1k, making the engine shudder.

thoughts on why?

E Z Fix, No cost. It’s the ideal air control valve sticking because of carbon and gunk build up.
My First ST was an o1 4L V6, First started that problem after 175,000 miles. Normally it Idled smooth around 750. Then it started to Idle rough and sometimes not at all.
Not a high skill job
Just remove the top cover
Remove the Two screws,
unplug the connection.
Remove the control valve (carefully)
There is a small gasket, set aside
spray the crap out of it until the valve actuates smoothly back and forth with your screwdriver. Then reinstall
Don’t forget the gasket. Wouldn’t hurt to spray clean all over related parts and cables. Your ST will idle great.
I suggest run occasional fuel injector clearer and check clean or replace air filter too. Sometimes the cause is (Ford said) because using cheap or bad gasoline repeatedly

.

 

[Dan B]

2008 doesn't have the idle control valve so the above post won't help you.

You can take off the intake and check out the butterfly valve to see how bad it is. I ran a can of seafoam through mine when I had it and it did wonders to clean it up.

 

[OFFKILTER]

E Z Fix, No cost. It’s the ideal air control valve sticking because of carbon and gunk build up.
My First ST was an o1 4L V6, First started that problem after 175,000 miles. Normally it Idled smooth around 750. Then it started to Idle rough and sometimes not at all. Just remove the top cover
Remove the Two screws,
unplug the connection.
Remove the control valve (carefully)
There is a small gasket, set aside
spray the crap out of it until the valve actuates smoothly back and forth with your screwdriver. Then reinstall
Don’t forget the gasket. Wouldn’t hurt to spray clean all over related parts and cables. Your ST will idle great.
I suggest run occasional fuel injector clearer and check clean or replace air filter too. Sometimes the cause is (Ford said) because using cheap or bad gasoline repeatedlyView attachment 1737.

2008 doesn't have the idle control valve so the above post won't help you.

You can take off the intake and check out the butterfly valve to see how bad it is. I ran a can of seafoam through mine when I had it and it did wonders to clean it up.

Well scratch that IACV idea. Yeah run sea foam through it

 

[Dan B]

I should revise my post above to make it more clear and say, remove the intake pipe to the throttle body, not the intake manifold itself. You can remove the throttle body easily and clean it up completely that way but I'd still suggest the seafoam to clean up your intake, valves etc. once you reinstall everything. Behind the throttle body, there was a spacer and a gasket that I just reused so you shouldn't need anything but the seafoam and I used throttle body cleaner to clean the butterfly.

Let us know how it goes.