My 5.4l has been having the rough idle in cold temps for about 3 years. Last fall I replaced the MAF and it helped a bit. Then I reseated all the connections to the sensors. That also made it better. A rescan of the codes and my misfire codes were no longer present. I ended up with both banks lean codes. Replaced my spark plugs today and now the truck runs like new.

 

hello my fellow ford owning friends. my truck below freezing temperatures rough idles really bad to almost stalling when stopped at a light. i wasnt sure whether to crap or wind my watch changing out different parts until i came across another forum where quite a few of the guys on there changed out there intake manifold gasket(s) and there problem was forever solved. give this link a good read and see what these fellow ford owners went thru to finally fix their problem. i truly think this will help us all with the cold weather rough idle bs. im gonna do this as well as soon as i buy some extra parts to change as well as the gaskets since so much work goes into it, might as well change some other parts related to the air intake and vacuum lines or elbows or at least a good check on them since the manifold will be removed. gcstroop is the guy that did the work involved and goes into detail about what he did. on page 3 of the comment thread he figures the problem out with his dead set determination. heres the link and i hope this helps:

http://www.fordf150.net/forums/viewtopic.php?t=65607

 

You should go by code only and/or a trouble indication by looking at live data with a Scanner.
Codes 171/174 will cause rough idle and stalling if severe enough.
An IAC stuck closed will cause low idle and stalling.
A leaking or held open EGR will cause rough overall running.
A thermostat stuck open will run the motor too rich and affect idle and hot restart.
Plugs and coils will not. A code will set if they ever get that bad.
Mass Air meter will not cause rough idle either.
Just working on the motor fools you, like washing a truck makes it seem to run and feel better to drive.
Go with the system operation instead of what some one else did and learn about it.
Good luck.

 

I'm in Denver and having the same issue! To which shop did you take it that finally fixed the problem?

 

Quality express auto repair. Their address is 3801 Morrison Rd, Denver, CO. 80219

 

I have recently developed the rough idle issue. When I first bought the truck used with 40k on the odo it had this same issue. cleaned the TB and MAF and it cleared right up. Truck ran perfect for the last couple years. I had developed a misfire on a few cylinders and did not take care of the issue in time which ended up killing my passenger catalytic converter. I have replaced all the coil packs (replaced sparkplugs previously) and replaced both Cats.

Going to try to track down the cause of the rough idle this weekend. If I got it to run good before I think I can get it running good again. There is a lot of good info in this thread. Thanks to all that have contributed so far. Makes things much easier to get to the bottom of when you know where to start.

 

Did you ever get a solution to this? I have a 2000 Ford F150...5.4 V8...same exact thing. I swear it only acts up when it is colder outside. But when idling or coming to stop it acts like it is going to stall. No check engine light though.

 

Have you tried anything to fix it yet? Have you changed your IAC? Looked for any vacuum leaks? Changed the throttle body? Might be your intake gasket bad. Is happened before..

 

If you try to replace anything else other than the intake manifold gaskets, you'd be wasting money on unnecessary parts and labor. If it only does it when it's cold, it's your intake gasket. They are made of rubber which shrinks in lower temperatures letting unmetered air by the MAF into your engine. Good luck and Happy Holidays!

 

A stuck IAC will give you the EXACT the symptoms as a leaky intake gasket. And is actually more common problem

 

If your Ford 5.4 comes with multiple misfire and O2 sensor codes then you intake gaskets could be why it idles rough below 50 degrees.

I had the intake gaskets replaced last year and it fixed the engine idling problem when outside temperature went below 50.

 

When the temperature gets colder parts contract. After the engine warms up does the rough idle go away? A loose clamp or hose may loosen further when cold.

 

“When the temperature gets colder parts contract. After the engine warms up does the rough idle go away? A loose clamp or hose may loosen further when cold. Click the image to open in full size.”


When the truck outside temperature would say 50f or colder the F150 would run great on the highway but at idle would be rough even die sometimes. I had the intake gaskets replaced and now one year later my F150 will run and idle and may have a little more power. My thought is at 50F the engine goes into a rich air fuel mix and with the air leak it gets way to rich? Only a guess, but if the motor is hot and idle is rough and unaffected from a cold motor to a hot motor only below 50F, then I would think something is changing at 50F with the programing and my guess is the fuel to air mixture.