Bouncing idle at start sometimes...
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Mountain Pass
Joined: Jan 2006
Posts: 249
Likes: 2
From: Moody, AL
Bouncing idle at start sometimes...
Last year the original battery died in my 1995 F150 XLT Supercab 5.0. This year the same problem of dead battery and bouncing idle on some starts returned. I have installed a rebuilt alternator, and things have gotten better, but the idle will still drop to almost a stall on some starts. It is usually harder on very cold starts, but sometimes it will start fine cold and bounce the idle on a restart after a 10 minute drive.
I have gone through the Haynes, but before I get into that I am wondering if the dead alternator could have damaged the new battery? Of course a damaged battery would be the easiest fix, so I am hopefull. The Haynes refers to a few areas to cause this problem. I am thinking either a vacume problem, PCV, EGR, or sensor issue. This truck is all origional, with some hacking done by the previous owner, so anything is an option.
Any ideas would be appreciated.
I have gone through the Haynes, but before I get into that I am wondering if the dead alternator could have damaged the new battery? Of course a damaged battery would be the easiest fix, so I am hopefull. The Haynes refers to a few areas to cause this problem. I am thinking either a vacume problem, PCV, EGR, or sensor issue. This truck is all origional, with some hacking done by the previous owner, so anything is an option.
Any ideas would be appreciated.
Thread Starter
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Mountain Pass
Joined: Jan 2006
Posts: 249
Likes: 2
From: Moody, AL
I have been wanting a full tune up for a while. While I'm at it I will test some sensors and replace the VSS. She still has an exhaust leak I have to trace down.
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
IAC is a good place to start looking. It controls idle speed and if it's gummed up with carbon it will stick. Remove it, clean it and make sure the valve moves easily. If not, replace it. Very common idle issue.
Since you replaced the alternator, the battery should survive as long as you charged it up prior to using it again. The alt is not meant for full charging a dead battery.
Since you replaced the alternator, the battery should survive as long as you charged it up prior to using it again. The alt is not meant for full charging a dead battery.
Thread Starter
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Mountain Pass
Joined: Jan 2006
Posts: 249
Likes: 2
From: Moody, AL
IAC is a good place to start looking. It controls idle speed and if it's gummed up with carbon it will stick. Remove it, clean it and make sure the valve moves easily. If not, replace it. Very common idle issue.
Since you replaced the alternator, the battery should survive as long as you charged it up prior to using it again. The alt is not meant for full charging a dead battery.
Since you replaced the alternator, the battery should survive as long as you charged it up prior to using it again. The alt is not meant for full charging a dead battery.
Thread Starter
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Mountain Pass
Joined: Jan 2006
Posts: 249
Likes: 2
From: Moody, AL
I found that my PCV valve had jumped out of it seat. As I pulled on it the plastic broke in the hose. I used a tiny screwdriver to remove the plastic in the hose, but slightly split the hose. I then put in a new PCV valve. Now it will bounce the idle at some times. This is only after a full warm-up and shut down. Now once I put it in gear the bouncing stops. If not it will stop as soon as the truck moves. I know the speed sensor is faulty, so I wonder if this might be a factor. A full tune up is set for the near future. I am going to do new oil filter, spark plugs, plug wires, cap & rotor. This should get me off to a good start. I know a new water pump is needed soon.
Posting Guru
Joined: Sep 2008
Posts: 1,123
Likes: 4
From: Baltimore
Have you taken off the intake hoses at the throtlle body and sprayed cleaner in there? It does get gummed up where fuel treatment doesen't reach.
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Posting Guru
Joined: Jan 2009
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From: Mattawa Washington.
IAC is a good place to start looking. It controls idle speed and if it's gummed up with carbon it will stick. Remove it, clean it and make sure the valve moves easily. If not, replace it. Very common idle issue.
Since you replaced the alternator, the battery should survive as long as you charged it up prior to using it again. The alt is not meant for full charging a dead battery.
Since you replaced the alternator, the battery should survive as long as you charged it up prior to using it again. The alt is not meant for full charging a dead battery.
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Thread Starter
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Mountain Pass
Joined: Jan 2006
Posts: 249
Likes: 2
From: Moody, AL
I plan to remove the throttle body and clean the whole thing. I plan on doing this when I clean out the IAC.
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