Hey Guys:

I need some advise. I've got a 03 F150 4x4 4.6 auto. Lately my idle has been a bit rough, but when accelerating or cruising there's nothing rough at all. Plus sometimes it's taking more cranking time to start then it used to. I've got 75K on the truck and in the past couple months I've replaced the fuel filter and the IAC.

Any suggestions for the cause? I'm sure the crappy winter gas here in NH isn't helping things much.

Thanks in advance

 

About a month ago my 1998 F-150 started doing the same thing(@110,000 miles). It got to the point that it would not idle, it would cut off. At driving speed all was fine. CAUSE-Idle sensor was messed up and needed replacing, i also got the fuel injection system cleaned and a new fuel filter. NOW it runs and idels great. Hope this helps out.

 

I copied this link for somebody the other day, the article goes into detail on how he pulled the throttle body off and cleaned it thoroughly before his problem was solved.

https://www.f150online.com/forums/li...h+Idle+Problem

 

MY GOD MAN!!!
You just described what it's like to turn 40!

75k - maybe time for a tuneup (cops,wires,TB cleaning, sensors etc...)
The rough idle thing is famous.
IE: weak battery, low grade gas, humidity, bad wire, dirty TB, Ox Sensor
faulty COP, cat sleeping on manifold, etc........

These motors are so sensitive it's not funny.
Unless your throwing a code/CEL, I would think it's a very minor problem.

You could try running some Seafoam threw it, in many cases like yours it takes care of the problem. Do a search on this webpage and you will find lots of info on it (seafoam).

-cheers

 

Thanks guys!!!

So this is what turning 40 should have been like? Funny.... Turning 40 was easier than finding these stupid little problems with these trucks...

 

ALSO be sure to check your EGR valve. If it gets clogged with carbon deposits it will affect your idel, but not your acceleration. See some other ?'s in this thread for rough idel. I just had to replace my EGR valve, but you can clean it to save some money!

 

Guys, I'll tell you the truth. My rough idle in my 2000 5.4L was nothing more than a dirty air cleaner. I replaced that dude and I cannot believe the added performance. Rough idle has left. Better mpg. Madhappy is absolutely correct when he says these things are so sensitive. Good luck.