Idle problems

[gerald holland]

I have the 2000 Expedition with the small v-8. A few weeks ago the idle speed started wavering after I would slow down at a stop. It will rise and fall about 4 times and then it will steady out and be fine. Until the next time I came to a stop. Sometimes it will fall so far the engine will stall. I then start the engine and the idle speed is fine, until the next stop. I need help on this one.

 

[Killer Ride]

Check the IAC valve it is probably gunked up

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[docraymund]

Check all vacuum hoses for brittleness especially the one at the back, near the firewall.

 

[gerald holland]

I put on a new IAC valve and no change. BTW I have been using a mixture of Chevron 91 and E-85 for years and everything inside is very clean.

 

[Yupster Dog]

Why do you have three threads going about the same thing?
Refer all post to the one so everyone is not posting the same thing in different threads.
People want to help but not when you make it harder.

 

[John S]

Had the same issue with my 2000, put new idle control valve on, inexpensive part and 10 minute installation. Fixed my issue. Good luck

 

[VoxVeritatis]

Likely issue with hose(s). My original 2002 EB 5.4L vacuum hoses were so lightweight they just tended to disintegrate right through over the years, and my expy is garaged 100% when not driving. Also had an issue with the plastic intake manifold at the crossover. Idle valve was so cheap I threw it at mine as well, but I ended up replacing hoses and later the intake manifold which solved all issues. When the vacuum issues get bad enough you'll start to throw codes which point to O2 sensors. Is your CEL illuminated?

 

[gerald holland]

No CEL yet