engine revs up way too much when started
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Senior User
Joined: Sep 2003
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engine revs up way too much when started
I have an 85 302 with throttle body injection, and when i start it up it will rev way up. im not talking a little fast idle to warm up. Im talking 3,000rpm plus. what could be causing this? it doesnt do it all the time, and sometimes it doesnt idle down even after warming up.
Cargo Master
Joined: Apr 2003
Posts: 2,408
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From: Parkesburg PA
Vacuum leak, bad IAC (Idle air control) and/ or a bad TPS (throttle position sensor) come to mind.
Scan the computer (http://fordfuelinjection.com/?p=13) and see if there are any codes. If not, check for vacuum leaks. The upper to lower plenum gasket is known for failing.
Oh, and FYI they're supposed to rev to about 1,750rpms for 30sec or so to heat up the O2 sensor. (and I'll bet also to emulate a carbs "choke" setting...)
Scan the computer (http://fordfuelinjection.com/?p=13) and see if there are any codes. If not, check for vacuum leaks. The upper to lower plenum gasket is known for failing.
Oh, and FYI they're supposed to rev to about 1,750rpms for 30sec or so to heat up the O2 sensor. (and I'll bet also to emulate a carbs "choke" setting...)
Last edited by f100beatertruck; Oct 9, 2006 at 09:22 AM.
New User
Joined: Sep 2006
Posts: 12
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From: Terre Haute, IN
it will most likely be the IAC. A vacuum leak would kill it or make it sound like it's dying. TPS would have that effect, but it would make it drive horribly. Is it doing that? Driving awful? barely hitting the gas to make it go speed limit? Anything of the sorts?
)
