98 Expedition problems

[Eddie57]

My expedition has been giving me problems for the last 2 weeks. It will work fine for a couple of days then i will have trouble keeping it on. I have been researching the autoforums and have read that it might be the Idle Air Valve. How do I determine if it is the Idle Air Valve? I have changed the fuel filter, air filter, pvc valve, spark plugs and added fuel additives. They didn't help. Friday it worked like a charm, today I had to drive my other car to work. Anyone have any ideas if this might be the problem?

Thanks
Eddie

Ps:Where exactly is this IAV? Is it hard to replace and what does it look like.

[barrys92]

Your IAV is directly behind your throttle body, just slight to the left. It's about $50.00 from the auto parts store. I would take your vehicle into a Auto Zone and have them do a diagnostics test. It's free. Is the CHECK ENGINE light on? Is it a 5.4L or 4.6L? How many miles? As far as removal/install, it is not bad. You will need a 10mm socket and preferrably a 1/4 drive socket wrench due to the limited space. Be patient. Let me know how it goes as I am experiencing similar problems. I'll do the same. Go to your local Library and chk out a Chiltons. Big help!!

[Eddie57]

Originally Posted by barrys92

Your IAV is directly behind your throttle body, just slight to the left. It's about $50.00 from the auto parts store. I would take your vehicle into a Auto Zone and have them do a diagnostics test. It's free. Is the CHECK ENGINE light on? Is it a 5.4L or 4.6L? How many miles? As far as removal/install, it is not bad. You will need a 10mm socket and preferrably a 1/4 drive socket wrench due to the limited space. Be patient. Let me know how it goes as I am experiencing similar problems. I'll do the same. Go to your local Library and chk out a Chiltons. Big help!!

The vehicle won't stay on so I can't take it to have it checked. Do you suggest that I replace the IAV and see if it works or should I clean the throttle first. The check engine light had been on but i tightened the loose battery cable and it went away. Thanks for your reply.

Eddie

[barrys92]

Originally Posted by Eddie57

The vehicle won't stay on so I can't take it to have it checked. Do you suggest that I replace the IAV and see if it works or should I clean the throttle first. The check engine light had been on but i tightened the loose battery cable and it went away. Thanks for your reply.

Eddie

Eddie,

Is it a 5.4L or a 4.6L? Mine is a 5.4L so I might be able to help. It could be the o2 sensors, IAV or EGR valve. I am in the midst of it myself. I will see a good buddy tonight on my Expo. I'll let you know what he tells me.

Barry

[Eddie57]

Originally Posted by barrys92

Eddie,

Is it a 5.4L or a 4.6L? Mine is a 5.4L so I might be able to help. It could be the o2 sensors, IAV or EGR valve. I am in the midst of it myself. I will see a good buddy tonight on my Expo. I'll let you know what he tells me.

Barry

I just saw an old school friend and he's been a mechanic for 30 years. He says that I should first clean the throttle, then check for vacuum leaks. He told me to completely remove it and clean it well. He says that he has seen many expenditions and it's usually one of those two. He says its rarely the IAV, but you never know. He also said that he didn't think it was the oxygen sensors, which he said would come out on the code listing on the engine analysis if the throttle was clogged. I have been checking aroung the web and those 3 items you listed have been mentioned many times. My vehicle is a 5.4 liter engine with 101,000 miles on it. It was running great until this happened. Let me know what your buddy says. two heads are better than one.

GL
Eddie

[barrys92]

Yes, I will. By the way, how do you clean the throttle and chk for vac leaks?

[Eddie57]

Originally Posted by barrys92

Yes, I will. By the way, how do you clean the throttle and chk for vac leaks?

I was told to use carb or throttle cleaner. My friend suggested to completely remove the throttle and thoroughly clean it. Regarding the vacuum leaks, I am supposed to check for a hissing sound towards the back of the engine. This is supposed to determine if there are any leaks. Once you find the leaks it's just a matter of replacing the damaged hoses or connections. If anyone out there has any major experience doing this please post any helpful hints.

Thanks and keep in touch,
Eddie

[Eddie57]

Originally Posted by barrys92

Yes, I will. By the way, how do you clean the throttle and chk for vac leaks?

Barry,

I contacted a Ford expert on a website where you can ask them questions. He has been working with Ford/Lincoln/Mercury for 17 yrs. I believe. He's been troubleshooting for the last 7 years. I asked him on cleaning the throttle and this was his response:

"Eddie ok what you want to do is have someone without the vehicle running hold the gas peddle all the way down and you go out under the hood and remove the air filter tube which is were you saw the flap get an old tooth brush and while spraying inside tooth brush all around the throttle body. then with the throttle body close try to start the vehicle then spray some more and give it gas to keep it running . note it may be hard to start at first but it will. Good Luck"

I am going to try his recommendation. I got nothing to lose.
Eddie

[barrys92]

Originally Posted by Eddie57

My expedition has been giving me problems for the last 2 weeks. It will work fine for a couple of days then i will have trouble keeping it on. I have been researching the autoforums and have read that it might be the Idle Air Valve. How do I determine if it is the Idle Air Valve? I have changed the fuel filter, air filter, pvc valve, spark plugs and added fuel additives. They didn't help. Friday it worked like a charm, today I had to drive my other car to work. Anyone have any ideas if this might be the problem?

Thanks
Eddie

Ps:Where exactly is this IAV? Is it hard to replace and what does it look like.

Eddie,

I just got word from my mechanic. He said I had nothing more than a huge vacuum leak. There is a large hose right below the IAV. He said it is a bear to get to but it might be worth a try. Do you hear a hissing noise near the throttle / firewall area? Let me know.

Barry

[Eddie57]

Originally Posted by barrys92

Eddie,

I just got word from my mechanic. He said I had nothing more than a huge vacuum leak. There is a large hose right below the IAV. He said it is a bear to get to but it might be worth a try. Do you hear a hissing noise near the throttle / firewall area? Let me know.

Barry

I like a challenge. Atleast that's what I telll my girlfriend.

Thanks
Eddie

[bearcat329]

had the same prob with my 97, right below the idle air vlave, is the connection to the EGR valve, what happened was the 90 degree rubber connecter rotted thru, allowing the vacuum leak, kinda looks like a spark plug boot.
hth
Rick, Ore

[Eddie57]

Originally Posted by bearcat329

had the same prob with my 97, right below the idle air vlave, is the connection to the EGR valve, what happened was the 90 degree rubber connecter rotted thru, allowing the vacuum leak, kinda looks like a spark plug boot.
hth
Rick, Ore

What does that EGR valve look like, I am asking because I don't know what the IA valve looks like either.

Thanks
Eddie

[bearcat329]

the EGR valve plugs into the passenger side valve cover, right about in the middle, then a plastic hose is routed to the back of the intake manifold, right under the IAV.

[akader]

Eddie,

I am almost certain your problem is the Idle Air control valve. You are describing the same problem that I had and replacing it, fixed the problem.

[Eddie57]

Originally Posted by akader

Eddie,

I am almost certain your problem is the Idle Air control valve. You are describing the same problem that I had and replacing it, fixed the problem.

Forgive my ignorance, but what does the idle air valve do? I am assuming it regulates the air intake.

Thanks
Eddie