Hey guys,
First post on here for me. My problem is that I have a 99 Expedition with the 5.4 L. Engine will not start unless I'm pushing down some on the accelerator. The motor will stay running as long as I'm giving it gas. Engine just turns off if I take my foot off of accelerator. Recent work done was Full tune up, EGR valve replaced, Brand new alternator and new battery. I'm thinking fuel pump problem possibly, but I'm not sure, so I figured I would get some good advise from you guys--Thanks in advance.

 

Btw, engine has 140,000 mi on it and Check engine light is not coming on.

 

Your IAC valve is sticking in the closed postition.

You can try cleaning it. Be prepared to replace it if cleaning does not correct the problem. If cleaning does help, it can sometimes be only temporary ahd the valve will, in due time, require replacement.

One of the more common Ford problems, not just on these trucks.

Steve

 

I don't know about it shutting off, but if it won't crank unless the petal is slightly down, it could be the throttle position switch. This is a great description on how to check it: http://www.svtlightnings.com/svt/how-to/brooks-tps.htm

Edit- I like the guy above me's idea a lot better than mine. Try his first, and if it doesn't fix it, try mine. I'd bet money that his idea will fix it though.

 

Steve,
I believe you were correct. I read somewhere else on the internet that you can sometimes tap the iac with a hammer, so I just went outside and tried to start the truck again and it failed . I popped the hood and tapped the iac with a hammer, started the truck and voila, it started and stayed running without pushing down the accelerator. It looks like an easy replacement part to do myself. Is there any speacial things to know before I start on this? Just looks like two bolts and electrical harness connection.

 

Problem solved--It was the iac valve--Thanks

 

What does the IAC look like and the PCV?

 

Assuming you have a 5.4...... The IAC valve is located directly behind the throttle body. It is connected to the intake manifold elbow (don't know the exact term for it). It is a shiny metal cylinder with a black electrical plug. There is a tube running from the intake hose, to the driver's side of the intake elbow right beside the IAC.

The PCV valve is located directly below the main fuses, and the main power relay. It is plugged into the passanger's side valve cover.

 

Thanks Steve,
I woke up this morning, and my truck was doing the same thing. I tapped it with a wrench, and it fixed it. This evening after work, I proceded to take the upper intake off, and guess what I found...... The fellow that changed my alternator months ago put the intake pipe on incorrectly. The bottom of the pipe was sticking into the throttle body. My truck has been sucking dirt for months. I took the intake off, and inspected the IAC.... It was full of dirt. So I cleaned it and put it back on. It idles smoother now, and it hasn't gotten stuck again. (yet)

Thanks for the great advice! It's nice to know that there are people that know what they're talking about.