2003 4.6L idle revs then stalls over and over in park
05-11-2019, 01:14 PM
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[RESOLVED] 2003 4.6L idle revs then stalls over and over in park
So, this problem started recently. When I'd start the truck, it'd rev up pretty much like normal, then the idle would stall down to 100-200RPM briefly and bounce back up to normal. After a little while, it got to where it'd do it a couple times when you started the truck. Now it's doing it over and over, and only levels out after about 30 seconds - if at all.
The truck itself is driving fine otherwise. It doesn't do it when you're just stopped while driving, it's only when it's in park. It doesn't fully die (yet) while it's doing it. It also hasn't thrown a code (again, yet) about it. I'm thinking it's gotta be a fuel pressure issue of some kind. Maybe not the pump, but the filter? Or maybe the MAF?
The truck itself is driving fine otherwise. It doesn't do it when you're just stopped while driving, it's only when it's in park. It doesn't fully die (yet) while it's doing it. It also hasn't thrown a code (again, yet) about it. I'm thinking it's gotta be a fuel pressure issue of some kind. Maybe not the pump, but the filter? Or maybe the MAF?
Last edited by TheQuicksilver; 05-26-2019 at 01:52 PM. Reason: Marking as solved
05-11-2019, 02:03 PM
#2
Unplug the maf and see how it reacts.
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05-11-2019, 02:46 PM
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05-11-2019, 05:32 PM
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Most likely it would make it better if that's the problem.
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05-11-2019, 10:10 PM
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Well, the short answer is, I'm not sure if it is or isn't the issue, but I'm encouraged at least. I pulled it and started the truck and it started fine. I reconnected it and... it started fine. So I think tomorrow I'll give it a good cleaning and see where that leaves me.
05-11-2019, 10:40 PM
#6
Once you clean it, disconnect the battery negative (-) cable for no less than 15 mins. That'll reset KAM and allow the truck to go into learning mode and adapt to the sensors readings as well as your driving style. Sort of like rebooting a computer when it gets sluggish.
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05-24-2019, 01:06 PM
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Well, I cleaned the MAF and thought I was in the clear, but the problem came right back. The problem seems to be worse when the engine is hot, and I noticed (though this is more likely a symptom rather than the issue) that the vacuum sensor drops off as it stalls. I'm gonna try cleaning the throttle body and doing the KAM reset next.
05-24-2019, 01:25 PM
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When I'd start the truck, it'd rev up pretty much like normal, then the idle would stall down to 100-200RPM briefly and bounce back up to normal. After a little while, it got to where it'd do it a couple times when you started the truck. Now it's doing it over and over, and only levels out after about 30 seconds - if at all.
The truck itself is driving fine otherwise. It doesn't do it when you're just stopped while driving, it's only when it's in park. It doesn't fully die (yet) while it's doing it. It also hasn't thrown a code (again, yet) about it. I'm thinking it's gotta be a fuel pressure issue of some kind.
The truck itself is driving fine otherwise. It doesn't do it when you're just stopped while driving, it's only when it's in park. It doesn't fully die (yet) while it's doing it. It also hasn't thrown a code (again, yet) about it. I'm thinking it's gotta be a fuel pressure issue of some kind.
05-24-2019, 02:02 PM
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Good thought. I hadn't tested neutral. As far as I can tell, drive and reverse are fine - or at least the problem doesn't present itself at that point.
I just tested resetting the KAM, but that does not appear to have worked. I'm eyeing the IAC as a possibility. It was reading 12 ohms, which is fine, but maybe something else is going on there.
I just tested resetting the KAM, but that does not appear to have worked. I'm eyeing the IAC as a possibility. It was reading 12 ohms, which is fine, but maybe something else is going on there.