rough idle at first start...30 seconds maybe
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From: NY
rough idle at first start...30 seconds maybe
I've got a 00 5.4 lariat 4x4 with 150k miles....the other day when i started it after it had sat all night it idled rough for about 10 seconds, like it was missing and it just did it again today after it sat at work for 8.5 hours.......went away after about a minute...why would this be? I haven't changed the fuel filter in the 6 months I've had it....maybe thats bad? dirty throttle body? only time it does it is when u first start it, and its hit or miss, but then again its only happened twice....? any suggestions? no check engine light..
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From: Joplin MO
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From: NY
I dumped some $1.50 injector cleaner in it from family dollar no joke and it started to do it but 85% better then before, then almost immidiatly smoothed out and hasn't done it since...
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From: Easton, Pa.
How the motor and computer handles cold starts;
When the ignition switch goes through the RUN position, the computer looks at the coolant temperature sensor value to make a decision on how much extra fuel to use and to opens the IAC for extra air and high idle and even a change in ignition timing.
As the motor runs in the first approx minute, the OX sensors heat enough to begin to take control of fuel and the high idle begins to come down as the temperature rises.
Look at the posibility of a faulty temp sensor, sticky IAC first.
Adding fuel cleaner to the gas takes awhile to be effective if there is clogged injectors.
Note that if the IAC is sticky, it is usually nearly closed when the hot motor was last shut down so is stuck in the closed position after cooling down.
Starting a cold motor now can't get enough air unless the throttle is stepped on to give it more air.
As the motor heats, the IAC may work again until the next time.
On an elderly motor it pays to go over everything and head off issues before they happen.
It's called maintainece!
When the ignition switch goes through the RUN position, the computer looks at the coolant temperature sensor value to make a decision on how much extra fuel to use and to opens the IAC for extra air and high idle and even a change in ignition timing.
As the motor runs in the first approx minute, the OX sensors heat enough to begin to take control of fuel and the high idle begins to come down as the temperature rises.
Look at the posibility of a faulty temp sensor, sticky IAC first.
Adding fuel cleaner to the gas takes awhile to be effective if there is clogged injectors.
Note that if the IAC is sticky, it is usually nearly closed when the hot motor was last shut down so is stuck in the closed position after cooling down.
Starting a cold motor now can't get enough air unless the throttle is stepped on to give it more air.
As the motor heats, the IAC may work again until the next time.
On an elderly motor it pays to go over everything and head off issues before they happen.
It's called maintainece!
Thread Starter
|
Senior Member
Joined: Feb 2008
Posts: 516
Likes: 0
From: NY
How the motor and computer handles cold starts;
When the ignition switch goes through the RUN position, the computer looks at the coolant temperature sensor value to make a decision on how much extra fuel to use and to opens the IAC for extra air and high idle and even a change in ignition timing.
As the motor runs in the first approx minute, the OX sensors heat enough to begin to take control of fuel and the high idle begins to come down as the temperature rises.
Look at the posibility of a faulty temp sensor, sticky IAC first.
Adding fuel cleaner to the gas takes awhile to be effective if there is clogged injectors.
Note that if the IAC is sticky, it is usually nearly closed when the hot motor was last shut down so is stuck in the closed position after cooling down.
Starting a cold motor now can't get enough air unless the throttle is stepped on to give it more air.
As the motor heats, the IAC may work again until the next time.
On an elderly motor it pays to go over everything and head off issues before they happen.
It's called maintainece!
When the ignition switch goes through the RUN position, the computer looks at the coolant temperature sensor value to make a decision on how much extra fuel to use and to opens the IAC for extra air and high idle and even a change in ignition timing.
As the motor runs in the first approx minute, the OX sensors heat enough to begin to take control of fuel and the high idle begins to come down as the temperature rises.
Look at the posibility of a faulty temp sensor, sticky IAC first.
Adding fuel cleaner to the gas takes awhile to be effective if there is clogged injectors.
Note that if the IAC is sticky, it is usually nearly closed when the hot motor was last shut down so is stuck in the closed position after cooling down.
Starting a cold motor now can't get enough air unless the throttle is stepped on to give it more air.
As the motor heats, the IAC may work again until the next time.
On an elderly motor it pays to go over everything and head off issues before they happen.
It's called maintainece!
