Idle Question
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Trailering
Joined: Oct 2011
Posts: 15
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Idle Question
99 F-350 7.3L
Lately, I have noticed while waiting on my engine to warmup before I drive, it's idle does a dramatic shift in speed after about 5 minutes of warming up. I know there are different idle setpoints, but is it normal for the engine to idle higher, between 300 and 400 rpm, after the engine warms up? If I tap the pedal after it speeds up, it will revert back to the original low idle speed. To me, it would make more sense to do the opposite for it to heatup. So basically, is this normal? Or do I have something hooked/wired up incorrectly?
Lately, I have noticed while waiting on my engine to warmup before I drive, it's idle does a dramatic shift in speed after about 5 minutes of warming up. I know there are different idle setpoints, but is it normal for the engine to idle higher, between 300 and 400 rpm, after the engine warms up? If I tap the pedal after it speeds up, it will revert back to the original low idle speed. To me, it would make more sense to do the opposite for it to heatup. So basically, is this normal? Or do I have something hooked/wired up incorrectly?
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Trailering
Joined: Oct 2011
Posts: 15
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I understand the cold idle concept, however it has been doing it even though it has warmed up outside. I don't think it should be doing the cold idle all the time. Also, the engine idle increases after the truck is warmer. The cold idle should cause the idle to start out higher in the colder weather, then drop down once it is hot. It is doing the opposite.
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
How warm is warmed up outside and at what coolant/oil temps?
The 7.3L isn't my strong point, but the 6.0L has a similar feature. I've heard different numbers, as high as 40 degrees ambient temp and 150 degrees oil temp.
If the truck is doing it after it's warmed up sufficiently, you might want to start looking at the Intake Air Temp sensor and the Coolant and Oil Temp Sensors and see if they're giving off valid numbers.
The 7.3L isn't my strong point, but the 6.0L has a similar feature. I've heard different numbers, as high as 40 degrees ambient temp and 150 degrees oil temp.
If the truck is doing it after it's warmed up sufficiently, you might want to start looking at the Intake Air Temp sensor and the Coolant and Oil Temp Sensors and see if they're giving off valid numbers.
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Trailering
Joined: Oct 2011
Posts: 15
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That is the direction I figured I am heading. However, for some reason, I have recently discovered that I can not get my OBDII reader to connect to the computer. I know I could watch those sensors with the scanner, but may have another task at hand to get the scanner to work first.
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