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2003 f-150 4.2L idle problems

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Old 10-18-2009, 03:45 PM
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Default 2003 f-150 4.2L idle problems

Hi, I'm new to the site but I really like the format.

My conundrum has to do with my trucks idle, its a 2003 4.2L v-6 with 138,000 miles on it. When I start it up cold it wants to jump right up to about 2000 rpm, after it warms up sometimes it will idle normal, 850 rpm, and sometimes it wants to idle at 1200 - 1400 rpm. The truck runs good while I'm driving it and gets pretty good gas mileage, I take good care of it but I just cannot figure this problem out....any ideas??
Old 10-18-2009, 07:02 PM
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Welcome to the forum, have a 02 4.2L myself with 192K. Are you having any CEL activity? There is a TSB for our years concerning intake leaks at the plastic intake plenium chamber. Your higher idle could be related. Am absolutely bushed right now and not thinking clearly, keep us posted.
Old 12-02-2009, 10:53 AM
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Hi Gang, I replaced the idle control valve, repaired a small crack in the plinum and checked the hoses, but I am still having the same problem.
When the engine is cold, 2003 4.2L V-6 5 speed manual trans, and I turn the key it will jump right up to an idle of between 2000 - 2500 rpm, it will begin to drop down within about 15 seconds to about 1500 - 1700 rpm, when it is warm it idles normally at about 850 rpm, but while warm if I come to a stoplight the idle drops down gradually from about 1200 rpm to the 850, it drops down faster if I push the clutch pedal in. The check engine light is on but the truck runs good and gets good gas mileage, I have also replaced the o2 sensors on both manifolds. Don't really want to go to a shop......any clues??.....Thanks.....Tom
Old 12-02-2009, 11:02 AM
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Default idle problems

Hi Gang, I replaced the idle control valve, repaired a small crack in the plinum and checked the hoses, but I am still having the same problem.
When the engine is cold, 2003 4.2L V-6 5 speed manual trans, and I turn the key it will jump right up to an idle of between 2000 - 2500 rpm, it will begin to drop down within about 15 seconds to about 1500 - 1700 rpm, when it is warm it idles normally at about 850 rpm, but while warm if I come to a stoplight the idle drops down gradually from about 1200 rpm to the 850, it drops down faster if I push the clutch pedal in. The check engine light is on but the truck runs good and gets good gas mileage, I have also replaced the o2 sensors on both manifolds. Don't really want to go to a shop......any clues??.....Thanks.....Tom
Old 12-03-2009, 06:55 PM
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Have the codes pulled again. Where was the crack in the plenium?



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