finally got rid of the rough idle...mostly

[GPNyce]

I have had a pretty rough idle for the past year, and every morning just turning my Ex on would be a chore (had to keep it at about 2000 rpm just to keep it on... ). Well I have had a wide variety of aftermarket airfilters on my intake, and i had heard that the oil in the filters can get on the MAF. So every month i would take out the MAF sensor (i used a hammer and small screw driver to knock the pin out of those security screws), and clean it with electronic parts cleaner (make sure its the one that doesnt leave a residue!!!) Seemed to help a little bit, but not much.

After reading around here a bit, found out about the IAC. Figured I'd clean that too...disconnected the battery to clear the profile...and a whole lot more of that cleaner later, and it was good as new.

Then i said...hey while i got the intake off, might as well clean up the throttle body... ...STP throttle body cleaner that is safe for coated TB's works wonders. Also sprayed in a little seafoam deep creep...just for kicks...

As i was putting my air hoses back, i noticed one behind the intake seemed loose. So i pulled on it, and my whole PCV valve and 2 disconnected air hoses came out!!! Apparently they had come loose somehow, and they are in such a pain in the butt place to get to, that i never even noticed! (behind the intake, inbetween the firewall and block, 1 hose coming up from below...connects to PCV...then 2 hoses come off of PCV and go to each side of intake). Luckily i like to carry spare parts around in my 'sploder, so i had a new pcv layin around. put everything back together, and it idles GREAT!!! Even better than when i bought it 2 years and a whole lot of miles ago!!!

I will continue to clean my MAF, as it does seem to help, and now that a standard hex bit will get those bolts off...its a 2 min fix.

If you are having problems with your idle, you might want to check these out...especially those hard to reach hoses that you havent look at in awhile....

 

[Space Truckin']

For some reason people do not want to believe it, but a rough idle is usually caused by a vacuum leak. Thanks for sharing your story and helping to spread the word. Always look for vacuum leaks before you start spending money!

 

[Creatve]

do you have a 6cyl SOHC? i've been having rough idle problems for a good 3 years now and recently the vehicle is intermittently dieing whenever I put it in park and let it idle. it will idle soo low and shut off. luckily it only has done this when i have in in park, not at a stop light.

if your vehicle is the 6cyl, the two air hoses you mentioned, are they the ones that connect to the intake after the MAF sensor?

 

[GPNyce]

yes indeed, it is the 4.0L SOHC. And the 2 hoses coming from the pcv (from the back of the engine) attach to either side of the intake on top of the engine. you might want to try adjusting your idle...set it a little higher, that might stop the stalling when you stop.

 

[manaen]

If your talking about adjusting the throttle body stop screw, that is not an idle adjustment. the computer will always try to set the idle to approx 750rpm. If you turn this screw the computer will just reset the IAC until it maintains 750. True you can turn the screw so far that it overrides the working range of the IAC. However the whole point of the IAC is to maintain idle under varied load conditions (IE air conditioner pump engagement)

Creatve If your having idle problems I would suggest fixing the real issue, like GPNyce did, by fixing his vacuum leak. You will be much happier and your truck will run better.

 

[Jakee]

Not to be the negitive one in the thread, but I hope you didn't suck too much dirt in while the hoses were disconnected.

 

[Space Truckin']

Do not make mechanical adjustments to the idle! This is the base idle setting for the computer and must remain at 750 RPM. (Edit: Some engines use a reference of 500 RPM.) The computer will raise the idle to the proper level using the IAC (Idle Air Control).

The lower intake manifold gaskets and the PCV connections, including the plastic tee adaptor, are common causes of vacuum leaks. The intake gaskets have been revised by Ford to fix the original problem (very rough idle during cold starts).

 

[aldive]

Do not make mechanical adjustments to the idle! .

Amen; leave the screw alone.

 

[manaen]

Ford should put a sign there that says NOT AND IDLE SCREW!!
I've seen too many people use it to try to adjust idle and wonder why it didn't make a difference, and then wonder why their engine stumbles.

Having the proper setup is crucial to proper performance otherwise the computer will always be guessing

In thier defense it is counter intuitive if you've grown up working on carbs. But that is why we have forums like this!!

 

[GPNyce]

i guess you guys misunderstood me. by adjust the idle, i meant with a programmer...im not a total idiot...although i might act like one every now an then...

 

[GPNyce]

Not to be the negitive one in the thread, but I hope you didn't suck too much dirt in while the hoses were disconnected.

it seems to run a whole lot better now....although my start ups are still not perfect. some weekend ill prolly take off the entire intake and clean everything i can get too, but thats about as far as ill take it...(for now)

 

[Creatve]

ok i'll check all the vacuum hoses for leaks...how exactly do you do that? I mean i can check for cracks in the hoses and loose connections, but can you do something else like pour very little water w/soap on joints to see if the connection is tight(doubt this method would work due to it sucking air, not blowing out air) or some other method?

I do hear a hissing noise on top of the engine after i remove the SOHC plastic cover...i cant exactly tell if the hissing noise is due to a vacuum leak or the hissing noise(what i think sounds like hissing) is the sound of the internal engine parts moving.

oh ya i'll leave the throttle body screw alone, saw it last night. I was tempted to mess with it hehehe

 

[GPNyce]

just look for cracks or crumbling lines, should be pretty easy to see if you have one or not. if you can hear a hissing sound, you might have a leak...try feeling for air coming out of one of the hoses...remember, your fan will be pushing a lot of air over that part of the engine. you can also just give the hoses a little tug, to see if any have come loose. hope this helps.

 

[manaen]

i guess you guys misunderstood me. by adjust the idle, i meant with a programmer...im not a total idiot...although i might act like one every now an then...

I just wanted to make sure that you were not talking about the stop screw.

Carry on

 

[Space Truckin']

Isn’t language fun? There was no mention of the mechanical setscrew or an electronic programmer. More proof that perspective influences interpretation.

And now we return you to ”Who’s On First?”.

 

[GPNyce]

Isn’t language fun? There was no mention of the mechanical setscrew or an electronic programmer. More proof that perspective influences interpretation.
QUOTE]



very true!!

 

[spkhone]

i can't still find that pvc valve. i'm having issues with rough idle and stalling out if i don't put it in 1st.

 

[Space Truckin']

The PCV valve is in that mess of hoses wedged between the back of the intake manifold and the firewall.

 

[shipwreck6]

im havin the same problem on my 96 v6 4.0 only difference is mine runs at high idle between 900 to 1100 rpm but only at stop signs or red lights if its in park its fine no rough idle but still high rpm could this be the same problem or something entirely different please someone HELP. forgot to mention i did complete tune up plugs wires pcv plus lower intake gasket( done profesionally at a garage ) im very frustrated to say the least

 

[manaen]

im havin the same problem on my 96 v6 4.0 only difference is mine runs at high idle between 900 to 1100 rpm but only at stop signs or red lights if its in park its fine no rough idle but still high rpm could this be the same problem or something entirely different please someone HELP. forgot to mention i did complete tune up plugs wires pcv plus lower intake gasket( done profesionally at a garage ) im very frustrated to say the least

could be, it's worth taking alook at the IAC, BTW in the future start your own thread you will get a lot more answers that way..

Oh and welcome to the forum