Weird idle issue
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Senior User
Joined: May 2012
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From: Decatur
Weird idle issue
I have my truck idling in the driveway while doing a coolant flush and it developed a weird idle. It will idle fine for a while then all of a sudden it will idle up a little for about 3 seconds then go back down. It will do this 3-4 times then go back to a regular idle for a while. I got in and watched my SCT X4 to see if anything changes. My actually RPM didn't change and neither did my fuel pressure or anything but my turbo added about 1.5 pounds of boost when it does it. It happens about every 4-5 minutes. Any idea what it is?
Postmaster
Joined: Aug 2015
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From: NW IA
I think what you are hearing is the vanes slowly sweeping. I have heard of other cases where it will do this with extended periods of idle, and IIRC noticed it last month when ours was sitting in the driveway for ten minutes at idle.
Speed did not change but the exhaust pitch does just slightly, not as loud as when it's started up first thing cold.
Speed did not change but the exhaust pitch does just slightly, not as loud as when it's started up first thing cold.
Lead Driver
Joined: May 2014
Posts: 6,545
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From: Virginia Beach VA
And switch to 5w-40 Delo 400 LE oil. Full synthetic runs cleaner and the ICP is sticking most likely. If that doesn't do it, pull the IPR and check it.
Should be no oil in the ICP connector or where the sensor plugs in.
Should be no oil in the ICP connector or where the sensor plugs in.
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Senior User
Joined: May 2012
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From: Decatur
My icp doesn't have oil in it and I'm not worried about the icp yet because I'm getting my oil cooler and studs done and egr delete next week. My truck only runs full synthetic rotella t6 and oem filter.
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Lead Driver
Joined: May 2014
Posts: 6,545
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From: Virginia Beach VA
The ICP may be the reason it's bucking at idle... run it with it unplugged, if it's stops, then you need a new one.
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Postmaster
Joined: Aug 2015
Posts: 3,910
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From: NW IA
From what I know, VXCF9 is the flash but I just assumed all 6.0's did this as start up. Not sure about extended idle but I know of one at the farm that will do it even at a stoplight.
This might explain why the OP sees a slight boost increase but not a change in RPM?
This might explain why the OP sees a slight boost increase but not a change in RPM?
Laughing Gas
Joined: Feb 2016
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I believe mine will vane sweep about 2-3 minutes from a cold start. I'll see VGT go to 85 and there's more of a rumble from the engine. I've never had boost on the SG2 to see what it does. Any boost change isn't obvious on the factory gauge.
i don't recall it doing it at a hot idle.
i don't recall it doing it at a hot idle.
Lead Driver
Joined: Dec 2006
Posts: 6,496
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From: So. Jersey
I think what you are hearing is the vanes slowly sweeping. I have heard of other cases where it will do this with extended periods of idle, and IIRC noticed it last month when ours was sitting in the driveway for ten minutes at idle.
Speed did not change but the exhaust pitch does just slightly, not as loud as when it's started up first thing cold.
Speed did not change but the exhaust pitch does just slightly, not as loud as when it's started up first thing cold.
I didn't notice mine doing it until after I programmed it with the SCT and Gearheads tunes.
There are YouTube videos on this. Do a search and take a listen and compare. Also monitor VGT solenoid when it does it and you'll see the % climb up and back down in sync with the sound. Also if you have a quality scanner you can perform a test that also replicates this.
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