High Idle vs. speed
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High Idle vs. speed
New to this forum so not sure if this is the correct place to post this question. Have an 2001 F-150 with a small V-8, five speed standard. When I push the clutch in, or put in neutral, engine remains at high RPM (1,500 - 2,500) until truck speed drops below at least 10 MPH. This happens when the truck is moving in forward or reverse. My mechanic has done everything he can think of including having the main chip erased and re-programed. Can anybody help?
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Joined: Aug 2001
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From: Trussville, Alabama
tj,
First off, welcome to FTE! I hope you enjoy it and hang around a while.
I seem to remember quite a while back, somebody somewhere mentioned this and I seem to remember that it was "normal". That is to say, it is not a problem that needs fixing. I can not remember what the reason was, but I seem to remember there being one.
I might be way off base. If so, somebody here will probably clear it up for us.
First off, welcome to FTE! I hope you enjoy it and hang around a while.
I seem to remember quite a while back, somebody somewhere mentioned this and I seem to remember that it was "normal". That is to say, it is not a problem that needs fixing. I can not remember what the reason was, but I seem to remember there being one.
I might be way off base. If so, somebody here will probably clear it up for us.
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Joined: May 2003
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From: Maryland
HI,
I can tell you that my 2003 4.6 5 speed doesn't do this and I am sure that yours did not until something went amiss.
This may be some help.
I have noticed that when I am slowing down and push in the clutch the idle drops to 800 RPM. Just before the truck comes to a completes stop (maybe 2 mph), the idle drops to 700 RPM. Figure this is some sort of a clean air tactic.
So it is normal to have a slightly higher idle until speed drops to some set point. But is seems like your chip is choosing the wrong idle set point and wrong RPM.
Does your tach and speedometer register correctly?
Have you tried a Ford dealer?
Chip
I can tell you that my 2003 4.6 5 speed doesn't do this and I am sure that yours did not until something went amiss.
This may be some help.
I have noticed that when I am slowing down and push in the clutch the idle drops to 800 RPM. Just before the truck comes to a completes stop (maybe 2 mph), the idle drops to 700 RPM. Figure this is some sort of a clean air tactic.
So it is normal to have a slightly higher idle until speed drops to some set point. But is seems like your chip is choosing the wrong idle set point and wrong RPM.
Does your tach and speedometer register correctly?
Have you tried a Ford dealer?
Chip
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The slightly higher idle would be normal. But let's use this example: When traveling at about 75MPH the tach if reading about 2,300 RPM (the tach is working correctly); if I push in the clutch, or put it in neutral, and coast (no brakes) the engine RPM remains at the 2,300 RPM until the vehicle speed drops below about 10 MPH. This could take 15 to 20 minutes with a downhill grade. It didn't start doing this until I hit about 90,000 on the odometer.
Have had two (2) excellent mechanics look at it and both are scratching their heads. Would like to get an idea before I take it to a dealer for an Easter egg hunt.
Have had two (2) excellent mechanics look at it and both are scratching their heads. Would like to get an idea before I take it to a dealer for an Easter egg hunt.
Postmaster
Joined: Aug 2001
Posts: 4,532
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From: Trussville, Alabama
After reading more info and understanding more fully, let me correct myself.
That does not sound normal.
What is causing it, I do not know.
Interesting though.......
Do you have cruise control by any chance???
Sounds like crusie is holding the RPM up until it drops below 10 mph.
What if you go to neutral then touch the brake pedal?
That does not sound normal.
What is causing it, I do not know.
Interesting though.......
Do you have cruise control by any chance???
Sounds like crusie is holding the RPM up until it drops below 10 mph.
What if you go to neutral then touch the brake pedal?
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Yes, have cruise control. No, into neutral and then the brake does not decrease the engine RPM (or any other combination I can think of). Only thing that willmake the RPM drop is to decrease the speed below approx. 10 MPH. Mechanics say they have checked all the cruise control components and everything seems to be in order.
Before asked, the mechanics are using the latest software for their diagnostics computer (a handheld job with thumb wheels on either side that they plug in under the steering wheel).
Is there any kind of mechanical relays that may be gummed up or sticking that may affect the crusie control?
Before asked, the mechanics are using the latest software for their diagnostics computer (a handheld job with thumb wheels on either side that they plug in under the steering wheel).
Is there any kind of mechanical relays that may be gummed up or sticking that may affect the crusie control?
Postmaster
Joined: Aug 2001
Posts: 4,532
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From: Trussville, Alabama
Boy, it sure sounds like a cruise control problem doesn't it?
What if you found and removed the fuse for cruise control.
I'd sure try to find some way to 100% defeat cruise and see what happened.
I can't think of anything else that woudl cause this.
This is a goodie!!
What if you found and removed the fuse for cruise control.
I'd sure try to find some way to 100% defeat cruise and see what happened.
I can't think of anything else that woudl cause this.
This is a goodie!!
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Have triedfinding a relay or fuse that will disconnect the cruise control. No luck. Any ideas?
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try changing the air by-pass valve. It is the main idle control gadget. Some need just cleaning and a little lube around the little piston and spring inside.Do not use strong solvents or throttle cleaners they will wear out a special coating on the inside. Just a small brush should do it then a drop of oil to coat the rod(whipe excess).
It is preatty easy to get to and take out
n the bottom there are two holes from wich you can see the spring.
Also you can connect the 2 elecrical connector to a 9 volt battery and notice a small popping noise. That is a good sign that the valve is getting energized and in working condition.
I have a 99 4.6 v8 with 125k miles and when I changed the valve I even got a better gas mileage.
then I added k&n and bosch platinum splitfires and i gained more than 1 mile per gal
It is preatty easy to get to and take out
n the bottom there are two holes from wich you can see the spring.Also you can connect the 2 elecrical connector to a 9 volt battery and notice a small popping noise. That is a good sign that the valve is getting energized and in working condition.
I have a 99 4.6 v8 with 125k miles and when I changed the valve I even got a better gas mileage.
then I added k&n and bosch platinum splitfires and i gained more than 1 mile per gal
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