I have a 02 f150 5.4 with 46,000 miles on it. When idleing it seems rough and not very smooth. It idles around 600-650rpm which I think is a little low. My old 97 idled around 800-900rpm. I just put some STP fuel injection cleaner in it to day, I will see If that helps. Is there any else that I can do to get the rpm up when idleing and smooth it out any? PCV valve? Also I have heard that if you diconnect the battery It will restart the comp, IS this right? And if I were to do that would it hurt anything else?


Thanks Josh

 

Possibly bad gas? Maybe replace the fuel filter, strong possibility.

If you don't want to replace the fuel filter you could try some SeaFoam. It's about $4/can at any auto parts store. You can just pour it in your gas tank along with a fill up or you can do what I find works a lot better for rough idle. Do this, trust me it works great:

Pop the hood and loosen up the hose clamp to either the throttle body or the the one after the air filter. Start the truck, then start pouring the SeaFoam directly into the throttle body intake slowly. Pour as much as you can in until the engine dies, sometimes it won't die but it gets pretty rough. Put the hose and clamps back together. Start the truck again. Put it in 2nd gear and go down the road with the rpm around 4000. Don't let up until the white smoke is done coming from the tailpipes. There should be a lot of white smoke so don't think it's out of the ordinary. I guarantee after doing this your truck will idle better than it was.

I usually do this to my truck every other oil change, or twice a year, mainly because I don't put a lot of miles on my truck and dumping the SeaFoam in there cleans up all the carbon build up. Usually once a year I'll use a can of it in the fuel tank to clean up the fuel lines.

 

Check out TSB 05-4-17. It could be the EGR

 

I am going to pick up a fuel fitler later today and change it out. And see if that helps at all.

Also when I come out of school My truck takes a very long time to start. About 6-8 secs holding down the starter. I drive it for about 10 mins to school and it sits for 3hours and 45mins. when I come out this is when it will not start. And this is only when it will not start. It started every time fine over the weekend, but it happens always when it sits for 3hours and 45mins.

I am lost at what is cauings this.

Thanks for any help.

 

EGR. What and where is it?

Also could it be the PCV valve or The Ivac

Thanks

 

The EGR Valve stands for Exhaust Gas Recirculation. Exhaust gas is routed back into the combustion chamber because the exhausted air is much hotter than the intake air. By sending warmer gas into the combustion chamber, the air/fuel mix does not have to do as much work to heat up, and your engine runs more efficiently. Now, since exhaust gas doesn’t burn, it doesn’t exactly help with combustion. At higher RPM’s, this really isn’t noticable,
but at idle, the reintroduction of exhaust gas will cause a very rough idle and can cause stalling if to much is introduced into the combustion chamber. On the top of this web page click the TSB/ Recall tab. Click on the year of your truck. Look for 05-4-17. May have nothing to do with your problem, but it is in option to look into.

 

The IAC is notorius for idle problems. It is at the top/back of the intake manifold. Disconnect the harness, remove two bolts then pull it off and clean it out. If it improves the idle....replace it. Cleaning will only help for a little while.

 

yeah am going to clean mines this weekend :-)

 

Ford Fx4 do a search on the IAC or idle air control valve. Billy Bob is on the right track, my IAC went bad @ 45,000(rough idle& whinning noise).

 

where was whinning noise coming through? intake filter? like a hoooooo?

 

Sorry Deltasoft through the intake it was a whinning sound.

 

Thanks guys for the help.

The problem does seem to do it every time but like tonight when I came out of work it Idled around 800RPM, which was smooth. But as soon as I came to my first red light and came to an idle agian it was real rough about 650RPM.

I have also noitced like a clicking /tapping noise on the passages side. Could the ERG and/or the Iac Be making noise if they are not working right?

could this be the problem?

Thanks

 

Almost sounds like you are reaching to high idle speeds. My truck idles at 600-650 and 500 when in gear.

 

Can and how do you test the Iac to see if it is working right?

 

I have never tried to test it. There are only 2 bolts, and 1 wire harness, (2 wires), to remove it. It sits on the top/back of the intake manifold. Remove the plastic cover that covers the intake and you will see it. Takes all of about 5 minutes to remove so I just cleaned mine, put it back on..noticed a difference so I replaced it.