Upon star-up the engine idles very rough and sometimes has power surges. This happens after sitting over night or for only one hour. The engine coughs and hesitates, trying to obtain full power during the first 1/4 mile or less and will then start running smoothly. There is no engine service light showing and the local mechanic says the computer shows no problem. I disconnected / reconnected the battery cables which eliminated the problem for a week. Now upon start-up I can switch off and immediately restart the engine and it runs fine.
My 1997 lesabre has developed the same problem. I replaced plugs,wires,pcv valve and O2 sensor to no avail. Also tried several tanks of high octane. Yesterday I left the store and it wouldn't start at all. Had the car towed to a good local shop. Today they said it starts fine and has been all day! They checked everything they could think of and can find nothing wrong. The head mechanic suspects the crank sensor but said it should give a check engine lite if it was having a problem. Of course the third time I started it after picking it up the damn thing barely ran for a minute or so before finally smoothing out. No check eng lite. This is becoming very frustrating!
Comment to Guesttoo:
These are not the same automobiles. I don't know who posted the first problem, but I posted the second one and this is the only time I have posted a problem.
I will update you on my problem. A friend who had the same problem said his was caused by using gas with Ethenol. (Ethenol causes water in the gas tank). He switched to a gas without it and after a couple of tanks the problem stopped. I am on my second fill up with gasoline without Ethenol, but so far, my problem is no better.
http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html
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will not idle when cold?
http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html
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runs lean and idles rough?
http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
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Engine stumbles coming off idle when warm?
http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html
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Erratic idle on car?
http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html
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Low idle when cold out side?
http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html
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Idle Air Control (IAC)
Valve Replacing?
http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html
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Engine quits at idle?
http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html
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Car overheats and Air blows
hot at idle?
http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
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While stop engine idles
like cylinder missing?
http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
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This
will help.
Thanks.
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Usually answered in minutes!
Same problem, When I start the car after sitting for a couple of hours it runs rough, bucks and jerks and if you don't do anything it dies. If you rev the engine a few times and continue to try to get it to go it will smooth out and run fine. Takes about 2 minutes for it to correct itself. I have had two mechnics look at it, the computer shows nothing wrong, and they have looked at everything and can't find anything. I read somewhere that if you disconnect the battery the car might do that because the computer has to relearn how to idle the car. If that is true how do you correct it, because we did recently replace the battery.
Be not confused, these two posts are for the same automobile. The problem still has not been fixed.
It could possibly be the Idle Air Control Valve.
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