The idle is controlled by what is called IAC (idle air control motor). This motor has a little cone shape plunger and it moves onto and off of a seat by doing this it controls the idle by controlling a vacuum leak. When close no vacuum and low idle, when open it causes a vacuum leak and the idle goes up. I’m going to have you something easy to help me figure out what’s causing the problem. I need you to remove the hose to the throttle body to expose the plate. This plate controls the air going into the engine off idle. If your hand I want you to push open the plate and run your finger around we’re the plate seats if it is black I want you to put carb cleaner, brake cleaner intake cleaner or something like that on a rag and clean the whole area all the way around and while you are doing this look for a slot or hole that will be in front of the plate that’s the side closes to you. That is going to be were the idle air control motor gets it air from. What I want you to do is spray the cleaner in that opening while the truck is running a little at a time because you don’t want to flood the engine and you don’t want it to idle to high this will help to clean the carbon off the plunger and the seat of the IAC ok. One thing to think about is that if the check engine light is not on now this cause it to come on. By removing the hose off the throttle body it will effect other sensors try to leave them plugged in because it takes two faults to trigger the light. That means if you start your truck one time and clean the IAC. As long as you put it back together before you start it again the light will stay off. But if you unplug a sensor and turn the key on this will cause a hard fault meaning the ECM (Engine Control Module) see a missing sensor. But if you do cause the light come on it will reset itself after the fault disappears or you can go to autozone and get them to clear the codes speaking of witch you should have them check for any codes first. Just tell them that you got some intake cleaner from them and the throttle baby service you did cause your check engine light to come on. They should clear it. Let me know how it runs after you finish there’s a good chance it may fix your problem if not it will help us to narrow down the problem. I will look the next few days for a reply. Good luck
If you need further help, I’m available over the phone at https://www.6ya.com/expert/edward_020b3320326d263d
SOURCE: Repalced O2 sensors, mass air flow sensor, and plugs error messag
dpfe velve
small emissions valve with one electrical connnector and three to four vacume lines located near your egr valve. this is a comon fault on fords emmissions system.
SOURCE: My 2004 Ford Expedition 4.6l has a rough idle and
well i'm sorry that you got the miss information here on fixya. because all internal combustion engines need a pcv valve to operate properly.
now the information you got first is correct and pcv valve can set false codes like o2's and lean bank conditions also can cause you vechile to run or idle rough.
no there are a few different styles pcv valves and some times don't look like your convetional pcv. some are heated in different ways either by coolant ( witch look like a conventioanl pcv but with a coolant tube around them) then electricaly heated and they don't look like them at all. but one thing that has to stay the same is the pcv valve has to ventilate the crank case and will be found somewhere on or near the valve cover because it is the easiest and most accessible point of the engines crank case area. so i would look for that and usally on that vechile it is on the passanger side valve cover in the middle.
with that said and seeing you did all those repairs i would go right for that as my next step. but there is other thing that cold cause this issue like leaky injectors and is almost more likely becuase of the o2 sensor code and backfire. do you have the code # so i can look it up and best assist you?
see vechiles are hard to fix over the computer as i am trying so if you have any more question/info about this issue please ask and i will be glad to help.
Testimonial: "Cool thanks, i'll check the pcv valve/ line going into the back of the intake, if that doesn't work i'll go for the codes again....thanks again...."
SOURCE: Engine surge during warm up.
Try changing your PCV valve make sure the hose is clean and not full of oil. Also check the elbow end that goes to the intake they tend to collapse from oil saturation. Hope this helps.
SOURCE: 2000 expedition- mass air flow sensor and computer
Sound like you have a big vacuum leak. Check the hoses that attch the PCV valve on the valve cover on the passenger side. Also reach way back on top of the engine there's another hose there that is known for going bad. The dealer has those hoses and they call it the Heated PCV valve hose assembly. Very common problem.
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