99 Expedition XLT
5.4L
4x4

At 30 degrees the expedition will start no problem. At about 18 degrees outside temp or less it will not start unless I give it gas. It has new plugs, new fuel filter, new gas cap, clean k&n air filter, repaired vacuum hose that was sucking shut. I was not having this problem until the radiator was replaced. After it was replaced the front heater core was plugged partially. It still started fine though. Now that I had the heater core flushed and the rest of the system flushed it will not start like it is suppposed to when it is cold. The other day at 18 degrees it did start on its own, but only idled at 350 rpms. When I turned the heater control in the front from medium to low it was able to kick the rpms up to where they should be at start. The charging system and the battery check out fine. It cranks over fine as well. I have 5-20 weight oil in it. Another problem that may or may not be related is sometimes I lose my vacuum I believe to the heater controls. If i have it on panel and feet, I go up a hill and the engine lugs down a little bit, the heater changes to the defrost. When the engine lug is over it switches back to panel and floor. Any help would be appreciated. Thanks.
Fred

 

I would check for vacuum leaks. The change to defrost when under load is an indicator of that. The vacuum issue would affect how the truck runs and idles.

 

Ditto on the vacuum issue. It sounds like maybe a hose was knocked off, broken, or not put back on after the radiator replacement.

 

Thanks for the help. I was thinking that I still had a vacuum problem somewhere. Could it be possible that it has to deal with the same line I had problems with before? The one I had problems with before was the one that runs to the back of the engine as well as to the pcv. I was thinking that this line could at least be plugged due to the fact that I found about an eight of an inch of buildup in the throttle body. It is hard for me to work on it right now because I was in a car accident on wed and I have for the old term "whiplash". Not sure what they call it now but it is basically the same thing. If nothing else I will try to find a reasonable priced mechanic down here to inspect the lines. Thanks again!
Fred

 

maybee a fuel issue with freezing also just to be sure drop in some dry gas and def get vac checked

 

I have put gas line antifreeze and water in the gas tank, but still the same problem. Is there an easy way to check for vacuum leaks that I can do myself? I tried to listen for any but the engine is too loud. I can not hear anything with it off. I had the oil changed at ford and they put in 5w 20 synthetic blend (standard now i guess) and now the lifters chatter enough that I can not hear anything if I wanted to. Took it to ford and they say it will not hurt anything. I just bought it a couple of months ago. It has 112,000 miles on it. A guy I talked to also said possibly it could be something to do with the air filter temp sensor, or the temp sensor for the block. It runs fine after I get it running.

 

I checked out the vacuum lines. I found the line with the pcv valve was sucking shut. I replaced one bad boot earlier. Now the other two are bad. Hopefully I can get the new vacuum line assembly soon and change it. Is there any way to check the vacuum system to make sure it has proper vacuum, or do I have to visually inspect all of the lines? There is one line that goes behind the engine that I can not see. The ones I can see seem to look fine. Are these boots rotting and sucking shut a sign that I need to replace all of the rubber vacuum lines and boots? I have never had this problem before with any vehicle so I am unsure what to do besides replace the one I know is bad for sure.

 

First replace just the bad one to see if the problem clears up. No need to confuse the current issue. If the problem is fixed by replacing the offending piece, then you can start inspecting and replacing any other questionable pieces.

 

Thanks for the help alloro.