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f100 hunting idle hard to start cold
hi all. my 05 f100 fuel inj has a hunt at idle and is very hard to start cold. black soot comes out exhaust which cant be good. ok so put comp over it all in spec iac,tps,new filters,vst clean 160 each cylinder,new plugs,new gas,inj flowed and checked,thermo sensor new,air flow metre also new. so after i get the girl going warmed up about 5mins slight hunt. if i pull the scavenger hose that goes to the air box off hunt stops idles beautiful. no fuel in oil . smell of fuel coming out when i take tube off when running. im running out of hair maybe some one will know what im dealing with before im bald. cheers and thanks in advance. rodbolt?
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Did you check air silencer for blockage or is hose being pinched closed with install back into silencer? -
yip everythhing clear and unobstructed. when it is hunting at idle i took the vacume hose off vst and sat at 1000 rpm smooth. it is like the fuel air mix is not right. iac,tps,therm sensor sort the comp for idle. comp doesnt like something to keep adjusting idle. i think im looking for something small? sorry for the delay in responding i live in nz cheersComment
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does anyone have any more ideas of poss cause cheers????Comment
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Fuel pressure in spec?Comment
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just tested iac on comp while running appears to be out . Q would this cause it to run rich ie hunt and smoke? i would imagine so. will order and see what happens. anyone agree witk thought line?Comment
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I have EXACTLY the same problem as you have described and I mean EXACTLY. I am getting to think the IAC too, but at the price I want to be sure before ordering. I guess what I want to know is ... How did you go? Did the new IAC fix problem? or was it something else?Comment
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dunno
last of the F100 in the US market was about 2002 and was carbed.
we never got the F100EFI motors.
black soot would indicate its rich.
could be a VST venting issue, ISC valve?? can be tested but typically a failure is rare other than mechanically stuck.Comment
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