03 f-150
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Trailering
Joined: Aug 2007
Posts: 17
Likes: 4
03 f-150
i've searched now for two days on this topic and found several threads that are close to my problem but not identical. so here it is.
on mornings that temps are below 50-55 degrees my idle becomes very erratic. it starts fine and idles up to about 1200 rpms and slowly starts coming down as it should. at about 900-1000 rpms/3-4 minutes of warm up the idle starts to surge up and down a few hundred rpms until fully warmed up. once warmed up or the temps get above 60 the truck runs flawless. the service light is on with the lean codes for both banks. i've cleaned the IAC, MAF, and checked all vacuum lines. truck had full tune up at 98K, plugs, wires, air filter, fuel filter. like i said, i've found many similar threads just none with the cold related issue. the truck has never died, stalled, or run poorly beyond idle.
on mornings that temps are below 50-55 degrees my idle becomes very erratic. it starts fine and idles up to about 1200 rpms and slowly starts coming down as it should. at about 900-1000 rpms/3-4 minutes of warm up the idle starts to surge up and down a few hundred rpms until fully warmed up. once warmed up or the temps get above 60 the truck runs flawless. the service light is on with the lean codes for both banks. i've cleaned the IAC, MAF, and checked all vacuum lines. truck had full tune up at 98K, plugs, wires, air filter, fuel filter. like i said, i've found many similar threads just none with the cold related issue. the truck has never died, stalled, or run poorly beyond idle.
Postmaster
Joined: Aug 2001
Posts: 4,532
Likes: 5
From: Trussville, Alabama
Did you see this thread?
https://www.ford-trucks.com/forums/8...tion-4-2l.html
I seem to remember someone having the same problem - apparently related to temp and warm up - some years back. I'll see if I can find it.
https://www.ford-trucks.com/forums/8...tion-4-2l.html
I seem to remember someone having the same problem - apparently related to temp and warm up - some years back. I'll see if I can find it.
Freshman User
Joined: Apr 2009
Posts: 25
Likes: 0
I believe the [COLOR=black][FONT=Arial][B]intake manifold isolator bolts are your problem. When I had the lean codes it began in cool weather and I found no vacuum leak finely took the upper intake off and changed the gasket and bolts problem gone. Good luck
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1987 - 1996 F150 & Larger F-Series Trucks
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