I have a 2000 Expedition that has a strange problem. After it has been run up to normal temperature and shut off, about four to five hours later, when trying to start it, it fires up, then shuts down. Most of the time after this it will start right up. A week ago was the first time that it would not start right up. I fooled with it for about an hour, and nothing. I could start it and keep it running by pedaling the gas, but if I let up, it just dies. Once it cools down, everything is fine. The Expedition is my wife's daily driver, so it does it to her everyday at lunch time. I drive it on the weekends, and never have a problem, because, everywhere we go, we are only there for a limited time, not long enough for it to act up. When it was acting up, I thought it might be a vacuum problem, but all the vacumm hoses look good. I scanned for codes, and it comes up clean. I checked the fuel pressure, and it reads about 31 psi while running, which I thought was kind of low, but is within the recommended range in the maintenance manual. It read 38 when priming, and spiked up to 40 when it is gunned. I hooked up a vacumm gauge, and it was steady.

Anyone have an issue like this before?

 

How many miles on the fuel filter?

 

Sticking Intake Air Controller (IAC).

 

I changed the fuel filter last week, with same results.

It has 130K.

I pulled the IAC off and sprayed some throttle body cleaner in it, but it didn't look it cleaned it much. It did look dirty. If it was the IAC, wouldn't it throw a code?

 

When you cleaned the IAC, did you work the pintel/plunger to make sure it is free.
This is the part that controls air bypass and must work freely or idle cannot be controlled.
There are related codes but seldom appear.

 

Bluegrass, I pulled the IAC off, and it does move, but is it supposed to spring back? It stays in what ever position I leave it in.

 

That sure fits the problem your having.
It's time to put a new one on.
It is supposed spring back to a closed position.
It's not a motor like many think.
It's a spring loaded dash pot type operation that he PCM hits with pulses so it reacts faster in one direction than the other.
No contol = poor/no idle control.

 

Thanks Bluegrass. I'll try that, and let you know the outcome.

 

Well, I haven't had the initial problem, but my wife hasn't taken it to work yet, and then gone to lunch. Now it bucks, as someone in this forum put their problem. When stopped at a stop sign, or a red light, the idle will drop down to 500, and then rev up to 1000 and then back down to normal. It is acting like the A/C is kicking on, but to extreme levels. It can also be reproduced about 90% of the time by coming to an abrupt stop. And, still no codes. This is after I replaced the IAC.

 

Some things to keep in mind.
The PCM had to adjust to the malfunction best it could, so a relearn may have to occurr.
There could always be an additional fault as well.
If you want, remove power from the system for at least 5 minutes.
This will reset 'all' tables to relearn.
Give it some days to settle and relearn to see if the problem goes away.

Some other things that happen when you decellerate is the fuel is shut down, the timing is advanced, the IAC is opened enough to keep the motor from stalling and some 'house-keeping' is done on the PCM tables.
You may just have to allow some extra time for all this because changing a part does not instantly fix a problem in many cases where the program has to readjust to the new conditions.
Remember, this is a 'live' system that does it's own thinking with logic.

 

Yeah, I thought about that too. Will cut the battery tonight, and fill you in on the results tomorrow. I drove it to work today, and did not get the start up issue, and the surging was minimal. BTW, thanks for the help.

 

That did it Bluegrass. She is purrin' like a kitten again. Thanks for all the help.