Idle problem
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New User
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Idle problem
I started having an idling problem. Truck was running fine couple of days ago. Noticed I had a weak battery. Tried to start in the morning and turned over a few times and went to clicking. Replaced the battery today w/ stock 65 series battery. Truck started fine and idled fine. Went into town, and while stopping at the first stop sign, I noticed truck idled way down to 200-300 rpm and almost died. It did die at the next stop sign. It started right up and I continued into town. While driving truck runs fine. When I stop, truck idle dives down again and then comes back up to @ 500-600 rpm or engine stalls. Tried cleaning the IAC, no different. When I start the truck, idle works fine between 700-800 rpm. If I rev the engine and let off the gas, engine rpm dives down and comes back up. Worse when the truck is in gear as expected. Just a coincedence w/ battery replacement or did something get fried? Should I replace the IAC. Truck has 4.6 v8 w/ @120k miles.
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It's a pretty straight forward battery replacement on the 97. No vac lines near battery. I did check thou. I was reading another thread about the same type of problem I am having. They were talking about the alternator being a possible cause. The worn alternator was putting a drag on the engine. Is this possible?
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Joined: Apr 2006
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Yes! Take off the serpentine belt and spin the alternator by hand to see if the bearings are shot. Or you could bring the truck to a local Autozone or mechanic to hook it up to an alternator/battery tester. That would be a good place to start. Since you just had to replace your battery maybe the alternator is going as well.
Tuned
Joined: Dec 2006
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From: houston,tx
There is a relearn strategy anytime the pcm loses power, it may act funny a day or so.
Also you may may need to clean the throttle body itself, where the throttle plates close inside the bore. Be sure to use a suitable (t-b safe) type cleaner and wipe them out with a rag. Sometimes an old toothbrush helps get in there.
Also you may may need to clean the throttle body itself, where the throttle plates close inside the bore. Be sure to use a suitable (t-b safe) type cleaner and wipe them out with a rag. Sometimes an old toothbrush helps get in there.
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ok, so this morning when i first started the truck it idled fine and i was able to drive normally until the truck warmed up (3-5 minutes). Then the truck would stall at every stop on the way to work. (pain in the ...) When I left work it acted exactly the same on the way home. I would think the pcm would have completed it's learning curve. The truck just idles so low it stalls. The CEL never stays on. I don't think there will be any codes to look at. I can restart it ok every time. Never has done this before until after battery changed.
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Joined: Dec 2006
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Not meaning to steal your thread...but how high should the truck be idling when stopped in drive?
Hope someone can help you...good luck.
~TJ~
Hope someone can help you...good luck.
~TJ~
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My son and I removed the serpentine belt and checked all accessories. all spin freely w/ no extra drag. We put a new belt on as the old one had 120k on it. We then replaced the iac valve and gasket, and took the truck for a test drive. After truck was warmed up, made several stops with it. Although it did not stall, it did idle down very low, and the truck would almost stall. I will drive it a couple of days to see if the pcm does any adjustment w/ the new iac.
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From: Louisville, Kentucky
Originally Posted by barneyfife410
Would a bad IAC through a P0401 code? I've already done the usual stuff for that code, replace DPSE, cleaned EGR Ports, MAF, etc. My 2001, 4.6L with 120,000 idles rough and I have the P0401 code.
