high idle problem SOLVED!
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Fleet Mechanic
Joined: Dec 2006
Posts: 1,338
Likes: 6
From: UPSTATE NY
high idle problem SOLVED!
special thanks to paw paw for all his help... but the problem is nothing what you wouldve expected. you'll never guess! it was the battery.
only and i mean only when i used to turn the a/c on, or any function that required the compressor to be on.... the idle would go through the roof!
this is such a rare problem that nobody has ever heard of and i would like to pass the knowledge along so i can save anybody else from any headaches. please add it to the tech section or wherever need be cause its a doozey!
the battery worked just fine the way it was, i've owned the truck for like 9 months now and its always started just fine, alternator did go out at one point and i replaced it but. so what really prompted me to replace the battery is that here and there it would crank the engine weak. and i looked at the age of the battery. it was old as hell! so i figured its preventative maintenance and bought a new battery thats the same 610 cca.
and it was a magic pill. and no there was nothing wrong with any of the battery terminals or cables and i didnt possibly wiggle anything that wouldve been that magic pill. the battery was the fix. and now i see why......
the alt and batt work together to power the vehicle. a/c compressor clutch requires lots of juice, and so does the fan for the cabin, especially if its hot as hell out and you turn the fan up. the battery and alternator team could not handle the load, so the computer went into some sort of mode that would crank the idle up through the roof. and then it was getting to the point where even if you turn the a/c off. the computer was still in that wierd mode. it was still telling the iac valve to go haywire. so i would then have to shut if off, restart it, and not touch the a/c. it now works like a champ and decellarates nicely too, and doesnt act like a wacko cruise control of death. (its a stick, if it was auto it probly wouldnt of been driveable.
so everybody whether you have a problem or not, and your battery is old, replace it anyway. spend the 80 bucks. because its a vital thing,
only and i mean only when i used to turn the a/c on, or any function that required the compressor to be on.... the idle would go through the roof!
this is such a rare problem that nobody has ever heard of and i would like to pass the knowledge along so i can save anybody else from any headaches. please add it to the tech section or wherever need be cause its a doozey!
the battery worked just fine the way it was, i've owned the truck for like 9 months now and its always started just fine, alternator did go out at one point and i replaced it but. so what really prompted me to replace the battery is that here and there it would crank the engine weak. and i looked at the age of the battery. it was old as hell! so i figured its preventative maintenance and bought a new battery thats the same 610 cca.
and it was a magic pill. and no there was nothing wrong with any of the battery terminals or cables and i didnt possibly wiggle anything that wouldve been that magic pill. the battery was the fix. and now i see why......
the alt and batt work together to power the vehicle. a/c compressor clutch requires lots of juice, and so does the fan for the cabin, especially if its hot as hell out and you turn the fan up. the battery and alternator team could not handle the load, so the computer went into some sort of mode that would crank the idle up through the roof. and then it was getting to the point where even if you turn the a/c off. the computer was still in that wierd mode. it was still telling the iac valve to go haywire. so i would then have to shut if off, restart it, and not touch the a/c. it now works like a champ and decellarates nicely too, and doesnt act like a wacko cruise control of death. (its a stick, if it was auto it probly wouldnt of been driveable.
so everybody whether you have a problem or not, and your battery is old, replace it anyway. spend the 80 bucks. because its a vital thing,
Laughing Gas
Joined: Aug 2003
Posts: 1,175
Likes: 9
From: So. Cal.
Kinda makes sense. The battery voltage was probably too low to supply enough juice to everything that wanted it, and at a normal idle, the alternator output was too low to bring up the voltage, so the computer did the next logical thing - it raised the idle until the alternator could supply the needed current. Which brings up the question of why the alternator wasn't doing it's job?
Moderator
Joined: Jan 2004
Posts: 13,851
Likes: 111
From: SW Va
Good find fix & feedback.
Not sure if I understand fully how the battery was causing this problem, but low battery voltage can cause some strange problems & this one is strange, as I too have never heard of this one!!!
With it having plenty of age on it & intermittently wimping out with a heavy electrical load when starting, was a good clue that you picked up on & one sure can't argue with your success!!!!
Here is a link to the second page, of your origional two page thread on this problem, for those interested in all of the symptoms & trouble shooting you did.
Might be helpful to others to post your battery findings in solving the problem & close out that tread. I noticed there was one other poster there that was saying he was having similar poblems.
https://www.ford-trucks.com/forums/9...problem-2.html
Not sure if I understand fully how the battery was causing this problem, but low battery voltage can cause some strange problems & this one is strange, as I too have never heard of this one!!!
With it having plenty of age on it & intermittently wimping out with a heavy electrical load when starting, was a good clue that you picked up on & one sure can't argue with your success!!!!
Here is a link to the second page, of your origional two page thread on this problem, for those interested in all of the symptoms & trouble shooting you did.
Might be helpful to others to post your battery findings in solving the problem & close out that tread. I noticed there was one other poster there that was saying he was having similar poblems.
https://www.ford-trucks.com/forums/9...problem-2.html
