Rough idle when cold

[Jerry Barnett]

I bought my Mustang in the summer and when starting cold it seemed a little of a jumpy, rough idle. Now that it has gotten colder and sat for 5 days I started it and it was very rough and almost stalling out. The RPM needle was bouncing and I had to hit the gas pedal at one point because it was possibly going to stall. After warming up it will smooth out. Also when first starting it will idle rough for about 10 seconds and then kicks into the mode where the RPMs go up as expected until it warms up and they come back down to normal. I had plugs done and always run premium gas. Any suggestions or thoughts? Thanks!

Sponsored

 

[luca1290]

What year is the car? New engines have double injection system and when cold they run only with the direct injection, so the problem may lie somewhere in the high pressure fuel system.

Do you have any way to diagnose the car?

 

[RazzaRossa]

He's got a 2015...

 

[17MagMetal]

I would guess a vac leak of some sort

Sponsored