EFI hunting Idle

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Dec 9, 2003 | 01:33 PM

Bogn

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Joined: Jun 1999

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From: Eveleth, MN

EFI hunting Idle

This is my first EFI 300-6 in a 89' f150 2x4 I bought yesterday. The Idle hunts on it and it goes between 400 and 1000rpm and does it all the time. This makes it a pain the in but to drive in town and I'm wondering what the main causes for this. I'm Thinking the IAC might be slow or sticking (have had that happen on my other EFI fords) but wacking it with a screwdrive handle didn't change anything (usually did on my other EFI fords) so I'm not sure its the IAC. What are the Other causes for Idle hunting on a EFI 6?

Dec 9, 2003 | 01:58 PM

f100guy

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From: shepherd

clean out the throttle body with throttle body cleaner. or maybe the tps is bad

Dec 9, 2003 | 06:43 PM

c_rossman

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Joined: Mar 2003

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From: Cloud USA

Also check for vacuum leaks. Throttle body gaskets getting sucked out is pretty common. Also those plastic vacuum lines tend to break real easy with a truck that old

Dec 9, 2003 | 10:37 PM

paulfix

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Joined: May 2003

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Try checking the ignition timing , mine was 20 btdc ( much too advances) and had a similar problem. I reset mine to 12 then to 14 and it runs sweet

Dec 9, 2003 | 10:38 PM

EPNCSU2006

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Joined: Nov 2002

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From: Concord, NC

Check the fuel pressure. Does it run rich?

Dec 10, 2003 | 09:24 AM

kidblueoval

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Joined: Dec 2003

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Ive experianced this before in my 88 4.9
what Ive done is remove the air cleaner tube and clean the throttle body. dont use carb cleaner because you could damage the 02 sensor, use only cleaner specified for use on fuel injected engines.
Good luck hope it works

Dec 14, 2003 | 12:47 AM

87joe302racetruck

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Joined: Dec 2003

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From: oc

efi hunting idle

i seem to have a similar problem except, my truck was warming up and then it would idle at 1/4 throttle had to put brakes on all the way to keep it from takin off. it would also go 35 mph without touching the gas peddle. a few days later it started idling low and when i come up to stop signs or lights it would stall out. just wondering if its my tps or something else.