Erattic idle/dies
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Trailering
Joined: Jun 2025
Posts: 17
Likes: 2
worked for about 2 days then started up again now going up to 3-3.5k rpms but it's either normal or all the way up there so it's not fluctuating anymore
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Trailering
Joined: Jun 2025
Posts: 17
Likes: 2
Thread Starter
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Trailering
Joined: Jun 2025
Posts: 17
Likes: 2
what exactly should I be looking for when I do that
More Turbo
Joined: Oct 2023
Posts: 607
Likes: 153
From: Canada
Warm up the truck until it idles ok. Then while its running unplug the idle air control. See what it does. The try to do the same when it's idling really high.
[ Unplugged idling normal ] you just try and drive it to make it do the problem again. And just see how it's running.
[ Unplugged high idle ]you want to shut it off. Wait a few minutes. And fire it back up and see if it does the same high idle. To let you know if your IAC is just getting stuck.
Now ill admit to skipping all these steps and just replacing the IAC motor since it's pretty cheap. And generally it fixes idle problems as long as they're not vacuum leaks.
[ Unplugged idling normal ] you just try and drive it to make it do the problem again. And just see how it's running.
[ Unplugged high idle ]you want to shut it off. Wait a few minutes. And fire it back up and see if it does the same high idle. To let you know if your IAC is just getting stuck.
Now ill admit to skipping all these steps and just replacing the IAC motor since it's pretty cheap. And generally it fixes idle problems as long as they're not vacuum leaks.
Thread Starter
|
Trailering
Joined: Jun 2025
Posts: 17
Likes: 2
Warm up the truck until it idles ok. Then while its running unplug the idle air control. See what it does. The try to do the same when it's idling really high.
[ Unplugged idling normal ] you just try and drive it to make it do the problem again. And just see how it's running.
[ Unplugged high idle ]you want to shut it off. Wait a few minutes. And fire it back up and see if it does the same high idle. To let you know if your IAC is just getting stuck.
Now ill admit to skipping all these steps and just replacing the IAC motor since it's pretty cheap. And generally it fixes idle problems as long as they're not vacuum leaks.
[ Unplugged idling normal ] you just try and drive it to make it do the problem again. And just see how it's running.
[ Unplugged high idle ]you want to shut it off. Wait a few minutes. And fire it back up and see if it does the same high idle. To let you know if your IAC is just getting stuck.
Now ill admit to skipping all these steps and just replacing the IAC motor since it's pretty cheap. And generally it fixes idle problems as long as they're not vacuum leaks.
More Turbo
Joined: Oct 2023
Posts: 607
Likes: 153
From: Canada
The usual culprit of early IAC failure is coking from a faulty EGR or blower or the circuit on the ECM itself is faulty. The EGR valve has about 100 000 miles of service life.
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Trailering
Joined: Jun 2025
Posts: 17
Likes: 2
I just put an egr on it it might be the ECM so I'll check that out I'll also need a obd2 reader cuz there is a check engine and it would have probably told me a lot but I like making my life difficult right lol
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Trailering
Joined: Jun 2025
Posts: 17
Likes: 2
just got the IAC in the mail, put it on and unplugged the batt for a while, I turned it on and was waiting for it to relearn, it's started at about 1.5k rpm then ramped up to 2.3k rpm and just stayed there till I turned it off
More Turbo
Joined: Oct 2023
Posts: 607
Likes: 153
From: Canada
Sheeeeit. It's supposed to be the exact opposite. Start at 2300 and dip to 1500 then settle to true idle. Is the computer already refurbished?
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Trailering
Joined: Jun 2025
Posts: 17
Likes: 2
don't know if last owner got a refurbished one or not, I tinkered with some connections/cleaned them and unplug the batt again and got it to kinda work, I found a new problem though, the spring on the throttle is to loose that it doesn't close fully so it gets stuck just barley off the idle plate so it "idles high" but it isn't fluctuating and being stupid off start up anymore. The spring is an easy fix gonna try to just re twist it so it's tighter if that don't work I'll buy new ones.
More Turbo
Joined: Oct 2023
Posts: 607
Likes: 153
From: Canada
don't know if last owner got a refurbished one or not, I tinkered with some connections/cleaned them and unplug the batt again and got it to kinda work, I found a new problem though, the spring on the throttle is to loose that it doesn't close fully so it gets stuck just barley off the idle plate so it "idles high" but it isn't fluctuating and being stupid off start up anymore. The spring is an easy fix gonna try to just re twist it so it's tighter if that don't work I'll buy new ones.
Thread Starter
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Trailering
Joined: Jun 2025
Posts: 17
Likes: 2
alright, will do. Thanks for all the help again man, saved me from spending a lot of money at a shop and got to learn more bout my truck.
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