Dynamic idle
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Dynamic idle
The recent cold snap has prompted my truck to have an increased rpm at idle during warm up and also if idling for any period where I assume it getscold enough to raise the rpms to generate a bit more heat. On my old 7.3 f250 it does the same thing. Only difference is on my 7.3 the idle drops back to normal if I touch the brake. My 17 just keeps reving away when the brake is applied. It drops when I throw it in gear, but idles up the second I put it back in park or neutral. I wanted to ask If others are having the same experience. I would assume this is normal since my brake sensor appears functioning correctly. I am so used to the brake kicking the idle down on the 7.3 it has my attention on the 6.7.
Tuned
Joined: Jan 2005
Posts: 433
Likes: 57
From: Bridgewater Ma
Yeah funny my 05 did the same thing, press the break it would shut off high idle. It's Normal. Once my 17 gets to the temp it needs it goes back to normal idle. Did it the other day when I stayed in the house longer then expected and went out and he was idling normal. These 17 and 18's are different Beasts!
Last edited by eryoung; Jan 6, 2018 at 08:33 AM. Reason: adding text
Logistics Pro
Joined: Feb 2005
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From: SEVA
Ditto. 18°F outside this morning, drove wife to get groceries and waited in the truck. Idled at normal level for a minute or two, then idle increased to 1,000 RPM. It slowed down when I touched the brake pedal. After the RPMs increased again, I found it also slowed down when I touched the accelerator.
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Ditto. 18°F outside this morning, drove wife to get groceries and waited in the truck. Idled at normal level for a minute or two, then idle increased to 1,000 RPM. It slowed down when I touched the brake pedal. After the RPMs increased again, I found it also slowed down when I touched the accelerator.
Hmm. I wonder why the two of you can kick it down and I can’t. Maybe as suggested above. It has to do with coolant temp. Can you kick your idle down right off a cold startup as well? Curious to see if it can be kicked down in two scenarios.The first that the truck is stone cold like the first startup in the morning where it idles up right off the bat. The second being you drove somewhere and then park and let idle long enough for the ecu to intervene to maintain coolant temp.
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Logistics Pro
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From: SEVA
Coolant temp wasn't even registering when it kicked down in my driveway before going to the store, and oil temp had warmed up to about 80° (remote started about 5 to 8 minutes earlier). Oil temp was over 130° while waiting in the parking lot, and coolant temp grew to about 2/3 of normal driving temp.
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Coolant temp wasn't even registering when it kicked down in my driveway before going to the store, and oil temp had warmed up to about 80° (remote started about 5 to 8 minutes earlier). Oil temp was over 130° while waiting in the parking lot, and coolant temp grew to about 2/3 of normal driving temp.
I went for a drive tonight and used the remote start to warm it up before going out. Got in and the oil emp was about 90 degrees. Still was unable to kick the idle down. I noticed you have the king ranch. I have an XLT. Since this is controlled through the pcm, I would have to imagine the kick down is a feature that is enabled in your pcm, and not enabled in mine. Why would they not make the high kick down/disable a standard feature or have it enabled one some trucks but not all. Historically it has been by default apparently until now.
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Joined: Jan 2005
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From: BC Canada
It's really a function of Intake Air Temperature. IAT being really cold, say negative f temp, idle is up to 1250 rpm, below 20 f, say 1000 rpm but will kick down, this is despite Oil and Water temps being below about 140 f. This is PCM programming which is model independent. Once coolant and or oil temps do rise above 140" or whatever the set point, then hi idle isn't needed. It just knows there is no way it's warming up at all without increasing RPM and fuel delivery if IAT is below a certain threshold, and once oil and or coolant temps get high enough, it will kick down on its own. Once I have Forscan working I will be able to figure these thresholds more exactly, but I am pretty sure that's the behavior I experience.
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rednekf350
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Dec 18, 2005 10:26 PM