Idle variation
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Senior User
Joined: May 2001
Posts: 198
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From: southern Ca
Idle variation
The wife's 2001 Expy seems to have a problem idling lately. We have the 4.6 and just recently installed a magnaflow muffler. Other than that everything is still stock. When we come to a stop sign right before we come to a complete stop the engine will jump up about 3 clicks, drop down around 5 clicks from there and then back up about 2. Then the engine will idle around 1500 and dance up to 1800 or so and may drop to 1300 occasionally. Maybe it has always done this and we didn't notice it because the truck is louder now with the new muffler. But now that we noticed the fluctuation I have been watching the tach on my 99 F-150 and it does not perform in this way and the 4.6 is stock on my P-cup. Do we need to bother looking into this. Driving down the road seems normal
JimP
JimP
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Joined: Jun 2003
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Idle variation
There is a rubber boot that connects a plastic hose to the back of the intake manifold. This boot is notorious for cracking or melting. Do a search on the forums for "expedition rough idle". I just found this problem my self. 25 dollar fix/ The hose is not visible.
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Senior User
Joined: May 2001
Posts: 198
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From: southern Ca
Idle variation
Are you talking about the hose that is about 1 1/4 inch in diameter and about a foot long? This hooks into the back of thBig elbow at the top of the engine. Is that the PCV valve
Senior User
Joined: Feb 2003
Posts: 369
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From: Bronx, New York
Idle variation
I think he means the one that comes out of the PCV valve, and goes around to the back of the intake manifold. Find the PCV valve (pass. side valve cover) and follow it around to the intake manifold. You can't see the hose, but you will feel it. The rubber gets mushy, and cracks...
Postmaster
Joined: May 2002
Posts: 3,028
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From: Annapolis, Maryland
Idle variation
Follow RTP's recommendation - apparently there's a rat's nest of hoses back there that can be purchased as an entire assembly. It gets all cracked and nasty and starts causing problems like you're describing.
XXL
XXL
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