Rough Idle

[ajspellm]

Hi,
My 2000 Ford Expedition with the 5.4l motor has been idling really rough when its cold in the mornings. Well it has become colder here in Nebraska and I have started to notice that it is now starting to idle really rough all the time. I cant notice any hesitation because I have only had it for a couple months. I was thinking about ordering a new idle air control valve to fix it but not sure if thats totally the problem. It does not have a check engine light on either but it just idles really rough when I am at a stop light. The rpms drop three or four hundred then go up and it just idles like it has a bigger cam. It has never died but I am afraid it is going to. Any ideas on what to check first? I was going to order that new iac valve off ebay since the expedition has 123,000 miles on it and might need a new one.
Thanks

 

[ELVATO]

Have you tried cleaning it? What does the RPM drop to? Mine starts to shake when the RPMs approach 600. Normally stays between 650-700.

 

[tonydiv]

The IAC itself won't make the truck run rough, it will only affect the idle speed. The IAC shouldn't cause a rough running condition during driving however. Coil packs are the most obvious place to start looking when the truck runs rough all the time.

 

[ajspellm]

I havent tried cleaning it. It drops to like 500 rpms or so I think. Maybe a little less but it idles really rough. It shakes pretty bad and I usually rev it up while sitting at a light. What should I look for on the coilpacs?

 

[JUST4FUN]

whats the mileage on the truck ? it might be time for a tune up

 

[ajspellm]

It just turned over to 123000 miles. I bought it from my grandparents a couple months ago and he kept up on the maintenance work religiously. I will have to ask him if he has had any problems with it idling weird and what stuff he has done to it. Its weird because it only happens when its like less than 40 degrees out.

 

[Lane24]

Sounds like a vacuum leak to me. Make sure to check the elbow on the vacuum hose going into the intake at the very back of the engine near the firewall under the IAC. Betcha got a hole in it. You can stick your finger right in there, and feel a suck.

Check this link for a better view. http://www.azda.com/ford/

 

[ajspellm]

Wow thanks for the help. That is probably it. I will have to check it when we are out of our blizzard here in Omaha lol.

 

[ajspellm]

I went to advance auto parts today and had the code checked out today and he said the code is that bank 1 is running and said I probably have a fuel injector that is plugged up. Is that code a sign the vacuum hose could be bad also?

 

[Lane24]

Was it codes P0171 and P0174 . Cuz that's the code everyone I've ever talked with had before they replaced their hose, or elbow.
The easiest way to check for a Vacuum leak is just to climb up onto your fan shroud, reach under all those hoses to the almost the back of your valve cover on the passenger side, and follow it along all the way to the firewall where it goes into the intake. ( With the engine running, so be careful) and you'll know if you have a vacuum leak. Not only can you hear it, you can feel it. It is quite a strong pull on your finger. It might even be collapsed, or cracked.
Just have a feel before you go replacing too many O2 sensors, or IAC's or MAF's or whatever the mechanic tells you you need. It's such a common problem there is a 7 year thread running on another Ford Truck site I am a member on.

I'm not saying this is for sure your problem, but just check it first before you go spending $$$. And make sure you have a new part before you take the old one off, cuz it will crumble in your fingers when you take it off!!!

 

[Lane24]

This is a picture of just the elbow...
And the whole hose is part #F85Z-6C324-AA.

 

[ajspellm]

Ok thanks for all the help. I asked the guy at the auto store and he said it probably wasnt that hose but I was thinking it probably was. Its weird it started acting up when it got cold though. It was fine before it got really cold.

 

[JUST4FUN]

Great info im going to sticky this

 

[Lane24]

Ok thanks for all the help. I asked the guy at the auto store and he said it probably wasnt that hose but I was thinking it probably was. Its weird it started acting up when it got cold though. It was fine before it got really cold.

Yeah, mine really started acting up when it got cold too. It actually got to the point that my CEL came on. I noticed it a few weeks ago that it was idling rough, but once the weather dropped below -20C it got so rough it would actually stall. Just check it... The "auto store" guy ain't gonna climb up under your hood and look for a leak. If I'm wrong, I'm wrong. But if I'm right you'll be very happy because it's then a $36 fix instead of a $500+ bill from your local stealership.

BTW the mechanic at the dealership isn't going to look for vacuum leaks. They are going to say you are running lean, or need an IAC because that's what their computer says. Until you look for yourself, you will just be replacing sensor after sensor, and still be idling rough.

But like I said, I could be wrong too. Just do me a favor and check before you go back to a shop.

 

[ajspellm]

Ya i dont think he really had an idea of what it was. I am sure thats what it is. It has to be according to what you described with your problem. I will have to check it out tomorrow after work. I emailed a dealer about the part and I hope I can get it tomorrow. Thanks for all the help

 

[ajspellm]

I went and got the part and installed it today. Seems that it is running better but will have to test in it in colder weather one morning. Thanks for the input.

 

[ajspellm]

Well got that new piece installed and it is doing the same thing again. It seemed better but now the check engine light came on again. Not sure what I should look at now? Any ideas?

 

[seeker]

Well got that new piece installed and it is doing the same thing again. It seemed better but now the check engine light came on again. Not sure what I should look at now? Any ideas?

Get the fault code. Sometimes when you correct one thingand then the underlying cause shows up. If the same code as before comes up you can see if there might be more than one possible cause. These can be a a pain but you have to take them one step at a time. I had a problem that took six months to finally throw a code. It sure felt good to correct it.

 

[Lane24]

Were you able to get the codes yet? Did you actually have the vacuum leak , or did you just replace the hose hoping it would help? Give us an update we'd like to hear your progress.

 

[ajspellm]

Well I have a update. I replaced the hose and elbow and it seemed to be better but then the next day the check engine light came on again. I took it into the dealer because I went on a 1500 mile round trip vacation and didnt want to break down during the drive. They replaced a different vacuum hose supposedly and said it was the one I had just replaced and said they put a bigger hose on. Driving home from the trip we were having a problem with the throttle sticking on the interstate and it getting stuck going 75 miles an hour. It seemed that when we let it sit for a little while it would quit doing it but it got pretty bad. Took it to the shop when we got back and they said it is a common problem in the expeditions for the throttle body to get dirty and stick when it is really cold. So they cleaned the throttle body for free and the next day I noticed it was idling really rough again. This was a few days ago and now today the check engine light popped on again so I called the shop I took it to and they said they are going to look at it again. I am going to take it into them Saturday and hopefully they can come up with a solution to it. Yesterday it was idling so low I couldnt believe it didnt shut down. It was down to around 400 rpm at red lights. I will give you guys a update once I get it back from the shop.