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Startup Fast Idle

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Old 05-20-2010, 09:34 AM
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Default Startup Fast Idle

I own a 2004 F-150 4.6L. I cleaned the throttle body and the map sensor both with the correct cleaning fluid. Now when the truck is started it goes to 1600 rpm and slowly works down to 800 or 900 rpm. This can't be good for the engine on cold start....


Any Ideas?

Craig
Old 05-20-2010, 10:20 AM
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The IAC might need cleaning to. Have you checked to see if any vacuum lines came unhooked?
Old 05-20-2010, 03:32 PM
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Default Idle air control Location

Originally Posted by rtg143
The IAC might need cleaning to. Have you checked to see if any vacuum lines came unhooked?
Yes I checked the vacuum lines...where is Idle control valve located in this truck?

Thanks,
Craig
Old 05-20-2010, 04:55 PM
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Originally Posted by Craig4937
I own a 2004 F-150 4.6L. I cleaned the throttle body and the map sensor both with the correct cleaning fluid. Now when the truck is started it goes to 1600 rpm and slowly works down to 800 or 900 rpm. This can't be good for the engine on cold start....


Any Ideas?

Craig
my 5.4L does it too even at 10° below.
Old 05-20-2010, 05:14 PM
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has it not always done this? its just the high idle at warmup. sounds normal to me
Old 05-21-2010, 09:48 AM
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Default High idle

Originally Posted by atvrider93
has it not always done this? its just the high idle at warmup. sounds normal to me
Its never been this high, maybe 1200 rpm...

Craig
Old 05-21-2010, 09:54 AM
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My 5.4 start up idle is 1200 and my dads 4.6 idle is only around a 1100 rpm so 1600 may be a little high.
Old 05-21-2010, 10:01 AM
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I have a 2005 STX 4.6 liter. I don't have a Tac so I can't tell what the rpm's are at startup but mine has always idled high at startup. Especially the colder it is. Less when the air temperature is warm. I figured this was normal.



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