Rough Idle

[gwinnch]

rough idle update for my '03

Update on my rough idle: After changing all the bad vacuum hoses i could find, it ran fine for a few weeks then started to occasionally rough idle at start up, which progressed to a bad coil code on one, then two cylinders. Went through 5 different ford coils that were all bad, then bought two from NAPA which solved the problem. Going strong for months, now-knock on wood!

 

[sgtowing]

Glad to hear

Sent from my DROID BIONIC using Tapatalk

 

[Big Red Monster]

If its that elbow would I smell unvurned gas very strongly from the tailpipes and under hood?

 

[ChrisUK]

Another thanks to Lane24! I found this thread last week while searching for error codes.

Just incase someone hase the elbow crumble on them, and they don't have the new part yet - I used some hight temp water hose, and a 90 degree joiner/connector which worked well (I live in the UK, so it takes a few weeks to get a part, so after reading this thread, checked all my lines and a few needed replacing)

 

[METALLICA]

guys how do you know if ur iac valve needs to be replaced?

 

[Big Red Monster]

@ metallica I think you can voltage test it, i just dont remember the correct volt reading that its supposed to have. have you had any luck on solving your problem?

 

[CARO'S98EB]

The easiest way to test it is to tap it with a hammer while it is acting up [idling slow] most of the time if it is bad the idle will pick right up. yes that is right you fix it with a hammer!!

 

[ardjaye4]

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/

hey good info, im getting the same code for my 2000 expedition 5.4L how do i fix the vaccum leak & will that part # also fit my truck?
thank

 

[Lane24]

hey good info, im getting the same code for my 2000 expedition 5.4L how do i fix the vaccum leak & will that part # also fit my truck?
thank

Click on the link above my sig pic. There is an entire write up on how to do this, part #'s etc.

 

[GregT]

sort of rough idle

hello guys i'm new to the forum at least on posting cause iv been following what you guys have been posting and referring to the site for general info on what i';m trying to accomplish so far it's helped me a great deal. here is the problem i have a 2003 expedition xlt and it idles sort of smooth you can feel a little shake if you pay attention to it ... the rpm gauge doesn't move at all and it idles somewhere around 650 to 700 .. it accelerates good but that little shake is annoying and i realize that it's not gonna run like if it's off the assembly line but i'm still trying to resolve it.. here's what if done so far.. i changed the air filter to a specter one i changed the fuel filter.. i changed the spark plugs and the boots all this has made it get better but i'm thinking of taking out the throttle body apart has any body had this issue ... the truck has around 120000 miles on it has any one taken the throttle body apart and found excessive gunk/carbon in it especially in the egr ports? i apologize for the long story/thread.

 

[GregT]

oh i forgot to mention i don't have any codes to provide i have not put a computer to test it out.. also if i'm on a never ending quest please advice as well hehe.

 

[buildingdoc]

guys how do you know if ur iac valve needs to be replaced?[/QUOTE

I used this and mine tested properly. It does involve tapping the TPS in the later steps and it's simple

Part 1 -TPS Test: Ford 4.6L, 5.4L (P0121, P0122, P0123).

 

[Johnymalangi]

The IAC itself won't create the vehicle run difficult, it will only impact the nonproductive rate. The IAC shouldn't cause a difficult operating situation during generating however. Coils features are the most apparent starting point looking when the vehicle operates difficult all the time.

 

[JEDIDADDYCHRIS]

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

Found one from Ford Parts Depot store on eBay, $44.96 with shipping.

 

[EddieH]

Don't put Bosch Double Platinum Plugs in 4.6 (too hot), stay away from Autolite professional series plug wires-Junk

 

[Pavelow369]

Alright, this is driving me nuts, truck (not mine, family, so I’m committed) 2003 5.4 230,000 hard soccer Mum miles. Cold days would get the P0171and P0174, but I’d clear the code and would be fine. Started running rough a week or two ago with the CEL flashing, code was that multiple cylinder misfire cant remember the code. So I replaced the plugs, which were nasty, corroded, and some of the boots fell apart. I didn’t know you could buy just the boots so I got two new from O’Rilies. Ran worse after and after a while got the P0171 and P0174. Found this forum, which is great by the way, figured I’d try the smoke machine method. Quickly McGyver’d one up using a lit cigar for the smoke source. Nothing…except for the IAC valve….not knowing any better that has an air bleed on it, I replaced it. Ran the same but would stall in drive, most of the time, and still idle rough and around 1500 rpm’s was the sweet spot for absolutely no power at all.. Checked all the vacuum lines, all the PCV lines, changes the PCV valve, even did the propane wand check with no results. Did the smoke check again, thought I saw the EGR valve leaking slightly, so replaced that, and found one of those EGF sensor lines cracked, replaced, cleaned bunch of crud from the TB, seafoam’d the engine…now it runs the same but doesn’t stall any more. Oh every time I work on this I disconnect the Batt the whole time so I assume the comp resets, so I give it some time to warm up and get adjusted.. I’ve disconnected and plugged most of the VAC lines, replacing the ones that looked bad. So the only common thing I haven’t done is actually remove all the PCV lines and that elbow below the IACV, get plenty of suction on the PCV and cant feel anything leaking at the elbow but am going to pull all tonight (found nothing).
I am at a loss…could this be an intake manifold leak from somewhere that wont show up on the smoke test? Should I pull all the plugs again and replace the boots, maybe throw the OEM coils back on with new boots. None of them really felt like they made any sort of positive contact, just sitting on the spring a bit. Fuel filter? Was running ok before…
Posted this on another thread, but havent got any responce.

 

[AnotherEXPYguy]

Solved rough idle

Pulled idle air control valve off cleaned with carb cleaner while I had it off checked the vac line directly under where the IAC sits and there is a 90degree boot that connects a vac line to the back of manifold and the boot was dry rotted and torn so I replaced that put the IAC back on and perfect idle

 

[AnotherEXPYguy]

Try to clean it before replacing pull it off spray it out with carb cleaner let it dry check the rubber 90 degree boot under it while your there it will rott and cause idle problems look on youtube for vids on cleaning the IAC

 

[bedrck46]

The EGR ports in the 4.6 tend to clog more so than on the 5.4 also clean the IAC valve and ports

 

[chuck48]

5.4l '98 EXPY stalls out after start

my '98 stalls after starting when you put it in gear, also when your going down the road and stop it will idles down and stalls out when the breaks are applied. I have removed the IAC and cleaned it and the intake. (no diffrent)