another idle problem

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Sep 16, 2011 | 07:26 PM

toby tough

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From: Clitherall, MN.

another idle problem

hey folks.new guy here with a question.i have a 92 f150 w/ a5.0 that idles very fast.somewhat like the fella that had the bad alternator.but i have replaced the tps,map sensor,iac and been all over the vac. lines and found no leaks. but when the engine is running and i climb up there i can hear a hissing sound even over the engine noise. what im wondering is about the air dump? gadgets behind the upper intake next to the firewall.could that be a source of a vac. leak?

Sep 17, 2011 | 06:46 AM

jplinville

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From: Ohio

Hissing denotes a vacuum leak...perhaps you've missed the leak.

Are you able to get your hand where the hissing is coming from?

Sep 17, 2011 | 07:40 AM

toby tough

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From: Clitherall, MN.

kinda tough to get to with the upper intake and all.but i think so. the air system back there has a couple vac. hoses to it i think.could be spooky with the engine running.years ago i had my shirt sleeve get pulled in to the alternater belton an old 67 catalina.very scary.