Cold rough idle

[bucks77ford]

I have a 99 Expedition 5.4L and since the weather has started to get colder, I've noticed that for a a little while until the engine gets warmer I have a rough idle on startup. Over the summer I replaced a vacuum hose on the rear of the motor to take care of that problem, so now I'm thinking a fuel/air mixture problem. Could this be the Idle Air Control Valve? I bought it this year, so I'm unsure if the coils and plugs have been changed. It has 138K miles. BTW, I have no check engine light on or anything.

 

[flareside_thunder]

Yes, it could definitely be a bad or dirty IAC. Alot of folks just clean the snot out of them ( and I am one of them) but they're really not even supposed to be and just need to be replaced. Cleaning it does not always solve the issue either. I'd also, at the very least, pull the plugs and check em out.

 

[bucks77ford]

Thanks for the reply. Also, after sitting again last night I jumped in it after work and it ran just fine. It seems to idle rougher the longer it sits. But, I'll start with IAC and take a look at my plugs. I'm thinking I want to change out the coils and plugs anyway, but I just don't have the time right now to do it.

 

[rford]

cold rough idle

My 2000 expedition is doing the same thing since cold weather started. Did you find the fix? Was it the IAC?

 

[rford]

cold rough idle

Thanks for the reply I will check it. I do not get on site to often, not much time available. all you FTF guys are a great resource.