So I have been thinking about this for a while. My truck has a rough idle and the dealer says it's 'normal'. I find this hard to believe that Ford would R&D and then produce an engine that they knew would idle poorly. I am wondering if the rough idle and poor gas mileage are dependant factors. So if you have a rough idle or poor fuel mileage or both please respond. Also please inform us of the model year of your truck, the engine, mileage, and a rating on how 'hard' you drive your truck (1-10, 10 being very hard) and any mods like intake, exhaust or tuner. My thoughts are that it is possibly an injector, air flow, or spark issue that is creating a lean or rich condition.

My scenerio:
2007 F150 5.4 4x4 12,200miles, driving habits=5, Edge Tuner
I average about 13mpg and have a rough idle (I have tried this on all settings on the Edge including stock and it is always there)

Thanks Guys

 

I have the rough idle since I bought the truck with 34,000 on it

 

Go into the settings on the Edge Evo and bump up the idle RPMs by about 150. I did this and the rough idle is gone. It seems that with the cooler weather, we turn off our air conditioners and the engine rpms at idle drop too low, thus creating a rough idle.

On a scale of 1 - 10 for driving habits, I would rate myself as a 3. very conservative. I am averaging 16-17 mpg in mixed driving.

For truck info look at the sig.

 

I had the rought idle until I started using better oil, I went from using crappy castrol gtx oil and switched to using royal purple synthetic, all I gotta say is the rough idle was gone. I also noticed a gain in HP AND better gas mileage!

From now on thats all i will be running in my truck.

 

I'm in a 04 4.6, I have the rough idle, but my mileage isn't bad I'm averaging around 16-17 mpg, with a blend of highway, and city traffic.

The only mod I have is a flowmaster si/do, and my driving would probably rate anywhere from a 5 to an 8 at the most, I'm not gunning it every chance I get, and I'm not mashing the pedal down to the firewall while on the freeways.

 

07 5.4
Intake, Exhaust, Edge Level 3
Rough idle 13mpg average
Drive like a 4.5 or so.
5500 miles.

 

Same thing here. 06, 4.6 the only thing is I didnt always have the rough idle. It came up around 25-28k and has been around since. My mechanic said he wants to clean the throttle body and see if that helps

 

hi all. i have a 2004 f150 4.6l 4x2 i bougth it new in 04. in december when i came home from college i started having some issues with it. it would idle really rough and shut off from time to time but no check engine light or nothing. a couple of days past and then the check engine light came on. so i took it to a buddys shop (good to have a mechanic as a friend) and he said to leave it so i left it and within an hour he called me and said it was ready. he told me all he did was clean the throttle boddy and the air intake tube (factory). weird but works really good now.

 

..sigh

yep, rough idle but not shutting off problem
gas mileage 16-22
2004 w/4.6 xlt scab

 

No rough idle (sounds like a diesel though) but poor gas mileage. Last few fill ups have been low 13's with Edge on Level 2. Next fill up is going to be premium on Level 3 and see if it gets any better.

 

Might want to have your cam phasers checked.

OP:
06 12.6k miles, seems to be idling rougher than it used to.
Hwy mpg 17+ but havent checked lately as I havent gone anywhere. City mileage on these 45+ hwy stop and go is 9-12 depending on traffic.

 

No idling problem at all but I am only avering about 13 mpg's. Damn crappy winter fuels! I do much better in warmer weather.

 

Granted I have only had my truck 5 weeks but I am getting a hair under 14mpg around here thus far.
I drove down to Charlotte for Christmas and averaged 18 mpg going 70-75 mph the entire way.
Considering my '91 has a 17.5 gallon tank it seems like I am doing really good until I get to the pump...and remember it is a 35 gallon tank.
It will be nice if that improves a bit in summer.

 

Thanks for all of the responses, mine feels like it has a mild cam. It isn't really terrible like its going to shut off or anything, but it is REALLY annoying. Anytime I sit in my truck with it running in park I want to go crazy because all I can think about is how my brand new truck is idling so crappy. Why do you recommend having the cam phasors checked?

 

Mine is the same way - had the cam phasers checked before I left the dealer with it and they said that they did not need replaced (it was under warranty at the time). I didn't trust their opinion and took it to two more garages - both said the cam phasers seemed fine.

2005 F150 Screw
5.4L/~56k miles/Edge Level 3/Flowmaster cat-back/K&N Filter/13-14 mpg/6-7 driving habits (Just got a too fast for conditions ticket on Sunday! )