Hey dburgjohn!
I am having the exact same problem and was wondering of you got that fixed and how'd you do it?
Thanks in advance

 

5 years and still fighting it

 

I got mine fixed!!!
Intake manifold gaskets!!
It was a real pain in the *** testing everything I could possible think of and not finding any leaks or defective parts (other than the MAF sensor which I replaced first and it made it run better but the problem was still there). Finally I decided to take the intake apart and replaced the gaskets. I realized it wasn't as hard as I though since only took me a one day of carefully removing parts, which aren't really a lot of parts as it seems, and it's running like new!!

What I found out is that the rubbing compound of the original gaskets from Ford is not very good and even worse if you live in a COLD area (below 32) because this rubber shrinks with cold weather and lets air into your engine that should be there and it's not metered by your MAF. It makes your MAF and O2 sensors go crazy making you think these are defective when they are not!

The new gaskets came with a different rubbing compound which is supposed to work a lot better!
So there it is!!!

TIP!!!
If your FORD 5.4 sets codes for one or both banks running lean (p0171, p0174) and also comes with multiple misfire (p0300) and O2 sensor codes, your O2 sensors are almost static at least in one bank, and your MAF sensor reads way below 5.4g/s (something like 3.2-3.8) then you intake gaskets could be defective!!!

Hope this helps!!!

Also, an auto repair shop shouldn't charge more than $500-$600 to do this job, including parts!

Dealer charges $900

 

My 2000, f150 runs rough anytime it gets below 50F. I don’t see how it could be an intake gasket as this would quickly heat up with the engine running?? Does anyone know where and how many sensor tell the motor what the ambient temperature is? Is their anyway to heat this up to 70Fon a 50F- outside temp?

 

you can try and clean you're IAC.
But there is a sensor inline right after the MAF sensor that senses intake air temp. You could clean that off too

 

Fred, your taking a light approach to your issue.
A Scanner to look at the live data will positively offer a lead direction to the problem.
A look at the short term fuel Trims for both banks will tell the story of either to rich or to lean condition.
From this, you then go after the cause.
First thing to look at is the IAT and CHT sensors for being out of tolerance in their resistance values. But even this is a guess without proof.
You must understand that taking a vehicle to a good shop is not an exercise in guessing and parts replacement to get lucky.
They should/would look at the parameters live before making any repairs so they know what to do and not charge you for parts and labor you don't need.
Good luck.

 

Believe me, I went through the exact same thinking about the engine warming up but the rubber on those gaskets, and I mean the ones Ford originally uses, is very tricky and I tested everything I could possibly test (spent 4 days at the shop on this car) and when I finally decided to replace the gasket I felt so relieved. I work at a mechanic shop and after that, many fords with the 5.4 came in with the exact problem and we got it fixed right away after testing and finding symptoms just to make sure (very common here in denver). Even yesterday A co-worked did one. And the owner of that truck confessed he had spent over $3000 trying to fix that problem and never did until yesterday.

But dont get me wrong, many other components could cause that problem, such as your MAF sensor or IAC valve. But those would cause the symptoms at any temperature. As someone already said, you need to look at the live data while your engine running with a scanner. Good luck!!

 

Yea, it's not the intake gaskets on the 5.4L causing that IMO. IF it was a 4.2L then yea, they're notorious for bad isolator bolts. I've never seen that problem with V8's/V10's. The 5fours and like eat the very front of the intake gaskets with time and even pit the aluminum surfaces. But yea, that's in front, just around water jackets. It wouldn't cause the issues your having unless coolant is somehow leaching from the intake and filling the spark plug chamber and/or dumping on the CHT. The CHT is very close to the water jackets.

Speaking of the plug chambers, you should inspect each one and blow them clean w/compressed air once in awhile. If anything made it's way into the chamber, -it's pretty much stuck there until you do something about it.

That's just something else you can check.

 

Hello! I migrated from ford enthusiast forum navigator n expedition. Have read your posts from beginning of ur rough idle in freezing temps. My expedition is doing the exact same thing- rough idle, decreased horsepower, etc. after spending 400 on new plugs, coil wires n fuel regulator, mechanic diagnosed leaking intake manifold after spraying starter fluid around edges of intake manifold. Rpms decreased when he sprayed where the leak was.

 

So it seems this is a common problem, mine has been doing everything listed for four years now. My issues started around the same time a spark plug detonated out the side of the threads destroying thehole. I was curious if any of you were experiencing very poor gas mileage as another side effect of these issues.

 

Crisrivas, Thanks as you said and I saw on a few web posts the gasket is the problem if it runs good when going down the road no misses until you come up on a stop and it only happens when the outside temperature is below 50 F and at an idle it will run rough and even die some times, but easy to restart and every time you step on the gas it will run like new. When outside temperatures stay over 50 F it will run like new also idle or on the road.

A note I had the spark plugs changed at the same time made it a lot cheaper and new boots on the plugs and a new thermostat made sense as its less labor to get it all done at one time.

My question earlier about finding the probe or temperature and tricking it to think it was over 50 F was to see if this made a difference as I would think if you have a vacuum leak and went into a rich gas mix at 50 F? this would cause a flooding and a rough idle.

Did not try this as I was not sure where or how to accomplish this. Does anyone know what changes on a F150 at 50F?

Truck runs good, idles good and I think has more power not sure. A BIG Thanks, Thanks, to everyone who helped.

 

My truck was getting 10-14MPG most OF THE TIME 10 mpg. I will check next tank to see if its changed with my New Intake Gaskets.

 

My f150 5.4L is running great, temp is in the teens outside cost for everything was $725 fixed by local shop.

 

Just a quick update
My 2000, f150, 5.4L is running great, the weather outside is cold and before I replaced the intake gaskets. When the outside temperatures drop to what they are now my f150 would have been idling rough and dying sometimes at stops. My F150 has a little more power but gas mileage sucks always has, the gas that is 12 MPG last tank. Once more a big thanks to everyone you saved me money and time.
Fredy

 

Hey Fredy, I'm really glad you solved your problem with the crazy idle as for the low gas mileage, if you haven't done a tune up recently, that'd be a good place to start. But another thing you can try is replacing your o2 sensors since their main function is to control gas delivery to your banks. ECT sensor and TPS can also affect a lot. Anything you do to fix that mpg, your truck will pay you back in gas consumption!