[oshelef]

We have a low mileage ~44k 2018 that has a rough idle at cold start, that smooths right out as soon as out into drive or reverse.

At cold start, in park/neutral it is rough and idling at about 1500rpm (maybe a bit less), put it in gear and it idles down to about 1000 and is very smooth. If you out it back into park or neutral, the rpm goes back up and the idle is rough again.

Seems like it happens only the first trip of the day. Never had any engine dash lights.

What might it be? Should I worry?

 

[SVTfocusO3]

May have codes stored, see stickied fuel injector and head gasket threads.

 

[Coastie05]

This was my exact issue and it turned out to be injectors. They hooked the computer up and saw my fuel trims were low, so they replaced them. Keep us posted with the fix.

 

[oshelef]

No obvious coolant loss or white smoke. Oil was maybe cloudy, but I chalked that up to fuel dillution.

Is there a way to check stored codes that don't trigger a light without a scan tool?

 

[SnakeCharmer]

If you do more short trips than highway driving, your engine may be suffering from cylinder wash-down. Check your oil level. If it's more than 1/8" above the full mark, you may consider changing the oil more often. This issue is a downside of the modern internal combustion engine design (ICE) that uses direct injection. Direct injection is a bad design. I hope the industry one day sees this and moves away from it.

One thing you may try is switching gas stations if you generally use the same one over and over. Sometimes it's fuel quality involved.

 

[oshelef]

your engine may be suffering from cylinder wash-down

I imagine that would cause milky oil and the lubrication consequences.

Would that also cause idle issues?

 

[SnakeCharmer]

I imagine that would cause milky oil and the lubrication consequences.

Would that also cause idle issues?

No, not milky oil. Milky oil is from a blown head gasket (oil/coolant mixed).

Wash-down is from having unburned fuel sitting in the combustion chamber. That fuel dilutes the oil to the point (at start-up) that the oil is no longer able to lubricate the cylinder wall and then slowly, the cylinder wall wears. Can be caused by a leaking fuel injector.

 

[oshelef]

Thanks for the explanation. I think you are telling me another consequence of whatever is causing the rough idle.

I'd need to have either a fuel injector or gasket issues to cause the rough idle (or something else).

And, additionally, I should change the oil more often to keep the oil lubricating well given the fuel diluting the oil.

 

[SnakeCharmer]

And, additionally, I should change the oil more often to keep the oil lubricating well given the fuel diluting the oil.

Especially so in a turbo charged engine that uses the engine oil to lubricate the turbo. Turbos get very hot and that further shortens the lifespan of the oil.

Anyway, I, as well as others here are interested to know what you find out for the cause of your issue, so please keep us informed.

 

[oshelef]

Will do. I think the next step is either the dealer, or checking for stored codes.

Is there an inexpensive code reader (or a way without a code reader) that would do that?

 

[SVTfocusO3]

Auto parts stores scan for free, Wal-Mart sells them, as well.

 

[oshelef]

One other thoughts - any connection to the fuel pump recall?

I think I'm past any warranty, so not excited to pay the dealer.

 

[SVTfocusO3]

Recall performed?

Not usually related.

 

[oshelef]

Recall performed?

Not usually related.

I've been recalled, but not replaced. I've got the "parts only for people with symptoms" letter on the fuel pump impeller recall.

 

[SVTfocusO3]

Ok, good to check the battery as well.

Report back with codes.