96 5.8 high idle
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Cross-Country
Joined: Jul 2003
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96 5.8 high idle
I have been working on a 96 f-350 5.8 idling real high not sure how high because i dont have a tach. I replaced iac and tps sensor still the same,but whats weird about it is when i unplug iac with engine running it idles down to almost perfect. Anyone have any ideas? Oh yea no codes. Thanks.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
It sounds like another vacuum leak.
Check all of the vacuum hoses, reservoirs, brake booster, & intake gaskets.
Also make sure your throttle plates are closing.
Check all of the vacuum hoses, reservoirs, brake booster, & intake gaskets.
Also make sure your throttle plates are closing.
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Cross-Country
Joined: Jul 2003
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when i was checking for vacuum leaks i found the left side exhaust manifold cracked.im pretty sure the throttle plates are closed they look like it unless previous owner tried to adjust set screw. its hard to tell.
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
If the throttle plates are closing the right amount then there is not enough air (O2) to keep the engine running when the IAC is closed (unplugged) and the engine will die. This is the only way the Computer can control the idle of the engine.
It opens what it thinks is enough to allow the right amount of O2 in but if some thing else is allowing O2 in then it will idle high.
It opens what it thinks is enough to allow the right amount of O2 in but if some thing else is allowing O2 in then it will idle high.
Posting Guru
Joined: Sep 2003
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maybe someone had the aic unplugged and adjusted the throttle blades like on a carb. look and see because the throttle blades should be closed completely at idle. i know i had trouble with my truck high idlng and thats what i did i opened the throttle blades to make it idle slower... but if you plug in the aic it idles at like 3,000 rpm. just leave it unplugged, thats what i di to mine, works great for me... sorry if i offend anyone for not letting the computer make idle adjustments. but i find that the computer makes the engine idle too high anyways. another thing is vacuum leaks like previously mentioned. vacuum leaks are bad, make exhaust temps run hot. melted pistons fried rings.