Fast Idle
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New User
Joined: Jul 2004
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Fast Idle
I have a 92 F150, 5.8, that has a fast idle problem. The problem has gotten progressively worse over the last couple of weeks. With the transmission in park, the rpm is at 1.5k, sometimes going as high as 2k. In drive, the rpm is at 1k minimum, sometimes going as high as 1.5k. The idle is always steady, not wavering, but consistently high. I have to use caution at stop lights to ensure I don't bump the car ahead of me. On a flat surface, the truck will maintain 45mph easy without aid of the accelerator. Any help with this would be appreciated.
Senior User
Joined: Aug 2004
Posts: 352
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From: Waukesha, WI
you might want to make sure your throttle body, cable, or pedal aren't sticking. My throttle body had weak(rusted) springs and it would take about 30 seconds for the throttle to close after I let my foot off the gas. Could also be the IAC valve.
Brian
Brian
Senior User
Joined: Jun 2004
Posts: 353
Likes: 3
From: Mid-Missouri
Check for intake air leaks or a large vaccum leak.
I'm not real familar with the 92 5.8, but aluminum upper intake to lower intake gasket usually goes bad on the 5.0 due to the differences in expansion and contraction between the two components.
cast iron and aluminum move at different rates. Eventually over taxes the gasket and lets air in behind the throttle.
I'm not real familar with the 92 5.8, but aluminum upper intake to lower intake gasket usually goes bad on the 5.0 due to the differences in expansion and contraction between the two components.
cast iron and aluminum move at different rates. Eventually over taxes the gasket and lets air in behind the throttle.
