Idle question
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
Yup, literally doesn't matter at all as long as its below 1.1 volts or so. On startup, the EEC looks at whatever value the TPS is at, and sets that as the base "idle" voltage.
Lead Driver
Joined: Feb 2002
Posts: 7,966
Likes: 595
From: Greater Austin, Texas
What does it idle at with the IAC disconnected? If it is still in the 1000RPM range, then see if backing off the throttle stop screw will lower the RPM. It is possible that a PO used this to set the idle speed and so your throttle blades are not closing enough.
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
Well, I feel like I eliminated everything except the throttle body so I ordered a new BBK unit. Even if it turns out not to be the issue, the stocker is 22 yrs old and will need replacing sooner than later. I'll update after installation.
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
Update: High idle in P or N remains and intermittent stumble at idle continues. I have replaced the following: IAC (Motorcraft), TPS (Motorcraft), EVR (Motorcraft), New BBK TB, all plastic vacuum lines replaced. I can hear an intermittent "whistling" at idle and low rpm driving, which seemed to start after the BBK install, so I know there is a vacuum leak somewhere. I tried spraying starting fluid around intake, TB and other suspect places but idle did not change. Vacuum canister was removed and painted and no holes or leaks found. A question about the iAC. When it is unplugged when truck is running, how should the idle respond?
Fleet Owner
Joined: Oct 2005
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From: Kentucky
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So I take it that is not the result you have? What is the idle rpm with the IAC unplugged?
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
Actually that is what mine does, just didn't know if that was what it's supposed to do.
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Tuned
Joined: Jan 2013
Posts: 305
Likes: 7
From: Middleburg, FL
Found the leak and thought I'd follow up on what I found. I made a homemade smoke tester out of a gallon paint can and used some incense for smoke and a small compressor to push the smoke. It was leaking from a place I would have never suspected, from my new Motorcraft IAC, and not from the gasket. The IAC has a metal cylinder that is crimped onto the body and contains the electrical parts and is supposed to be air tight at this seam, but that's where I had smoke coming out. Instead of buying another one I took it off and sealed the seam with silicone and I'll see if that works when I drive to work in the morning. If not, I'll have to replace it. It's been a month long pain in the *** and I hope it's over.
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