Rough Idle

[Retired Now]

I've got a 06 eddie bauer 4.0,engine, 120,000 miles, been a one owner well maintained unit, cold starting it fires up ,runs like a champ,this winter i noticed after it was warmed up and idling for a while,it starts to get a little rough idle,(barely noticeable) but its there,u can hear it in the exhaust,kinda sounds like a flutter,not a miss...and when starting after its warmed up, it will stumble a little before smoothing out to good idle, so i changed plugs,(little over due) all plugs in good shape gap was huge but no deposits on any, changed fuel filter, nothing changed as far as the idle issue.Over all it runs very well,no power loss,no engine rattles,etc, I'm expected it would throw a code when it stumbles on warm startup,but nothing flagged ???any suggestions where to look next ??
thanks

 

[V8SHO]

There are quite a few possibilities of what the cause could be, but if the problem only happens at idle, then I would first check for vacuum leaks. Try to look for any loose/broken vacuum lines around the engine bay and listen for any hissing, like any air escaping. If you have a scan tool that reads live data, you can also look at the primary O2 sensors to see if they are switching properly, that way you can eliminate them as a possibility.

One thing you could try that may help is to run some fuel system cleaner such as BG 44K, seafoam, or any other fuel cleaner you prefer. It may or may not fix the problem, but at 120K it wouldn't hurt to do so anyway, just like the spark plug change.

 

[Retired Now]

I usually give her a drink of seafoam twice a year, just as PM, but i'll certainly do some checking for a vac leak, thanks

 

[OkiePeach]

Would a vaccuum leak cause it to shake when you turn it off? I have on 06 XLT with the 4.0

 

[Mustang Guy]

Have you ever cleaned the throttle body and plate? When they get dirty it can cause idling issues.

 

[MotorCityFats13]

mine had a stumbley rough idle and today I changed the plugs and it got better.... then changed my fuel filter and its like 99% gone but this task is definitely the worst design of fuel filter placement I have ever had to deal with replacing

 

[Retired Now]

mine had a stumbley rough idle and today I changed the plugs and it got better.... then changed my fuel filter and its like 99% gone but this task is definitely the worst design of fuel filter placement I have ever had to deal with replacing

totally agree on the fuel filter change !!! huge pain.
will try the throttle clean soon.

 

[MotorCityFats13]

totally agree on the fuel filter change !!! huge pain.
will try the throttle clean soon.

I bought mine at 109k and I cleaned the t-body and mass air sensor the 2nd day I had it so I cant vouch for making it run better but mine was really carbed up and anytime you clean something that dirty your mind tells you its faster... same as my new plugs and fuel filter... I think my 4wd is running high 9's now.... in the 60ft lol

 

[V8SHO]

Glad to read that you fixed the rough idle on your Explorer, I too have been dealing with some idle issues on my '06 4.0 explorer but still have yet to pinpoint the cause. Like others have posted on this thread, I also replaced the plugs, wires, fuel filter, and cleaned the throttle body, but unfortunately still have a rough idle, no stalling and no check engine light. Upon cold start, idle bounces between 1200-1400 rpm for a minute before dropping to 900 rpm. It runs great above idle, very good performance and good gas mileage. When engine is fully warm in closed loop, long term fuel trims at idle are around +12 on both banks, indicating a lean condition. I probably have a vacuum leak somewhere but cannot find it anywhere. I read these vehicles don't have a separate IAC valve, it's built into the throttle body assembly, could a bad throttle body cause the rough idle? Does anyone know to test it?

Sorry to read about troubles on replacing the fuel filter, where was it located on your vehicle? I've seen some Explorers have the fuel filter fastened with a red plastic clip on one side and the ford not-so-quick connect steel clip on the other. The procedure seemed easy on mine, located under the passenger front door near the catalytic converter (behind a metal plate and bracket), and fuel lines were connected with two plastic squeeze clips, red on one side and green on the other.

 

[MotorCityFats13]

passenger side between the cat and the fuel tank hiding above a heat shield held on with 3 bolts and a plastic plate like thing held on by 2 nuts that holds it next to the fuel tank.... you cant fit more than 1 hand on the filter at a time and you almost have to do everything blind just by feel ... one side of the filter is removed by hand squeezing a plastic clip and a red clip that unlocks and then you use a locking line removing tool

 

[Retired Now]

haven't tried too hard to track it down yet, but last week it did its stumble on a warm startup idle, and stalled , when it did it that it thru a service engine code, i had the dealer read and clear the code,it was a mis-fire cylinder 1, he thought it maybe a weak coil, (I've replaced spark plugs) about 5k ago, shouldn't be plugs. ???

 

[V8SHO]

haven't tried too hard to track it down yet, but last week it did its stumble on a warm startup idle, and stalled , when it did it that it thru a service engine code, i had the dealer read and clear the code,it was a mis-fire cylinder 1, he thought it maybe a weak coil, (I've replaced spark plugs) about 5k ago, shouldn't be plugs. ???

When it stalled, did it restart immediately or did you have trouble getting it to restart? If the only code stored in the computer was a cylinder 1 misfire, then it could be a coil or fuel injector on cylinder 1 causing the problem. A few other possibilities might exist but would need to look for other clues. If you have a spark tester, you can test for spark on cylinder 1 and see if you have good spark.

 

[Retired Now]

When it stalled, did it restart immediately or did you have trouble getting it to restart? If the only code stored in the computer was a cylinder 1 misfire, then it could be a coil or fuel injector on cylinder 1 causing the problem. A few other possibilities might exist but would need to look for other clues. If you have a spark tester, you can test for spark on cylinder 1 and see if you have good spark.

restarted ok, and went on a smooth normal idle, its the one and only time it thru a code, and it only acts up when engine is warm, cold starts ,performs perfect.

 

[Ghary]

Were you able to figure it out? I have same issue on same car and cleaned T-body but did not fix it. Thanks

 

[Retired Now]

not yet, will post anything i try,

 

[Ghary]

A technician told me that it is the computer of the car that is causing this problem. Have you considered this?
He made a simple, silly test where he poured some cold water on the car PCM and it relieved the issue a bit. I don't know whether it is a good idea to put water on the computer.