VGT Duty Cycle???? - Ford Powerstroke Diesel Forum
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Old 07-20-2013, 09:47 AM
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VGT Duty Cycle????

Just recently bought an edge insight cts monitor. Have been having a few hiccups with my turbo, every once in a while while putting a load on the motor (going up a steep hill, hauling, etc.) while in cruise control if i'm going around 70 mph and the boost builds, around 18-19 psi it will sort of "skip" I can hear and feel the turbo skipping, the truck will lose power for a split second every time it does it. Now on to the vgt, when i first start the motor the vgt duty cycle reads around 75-80%, then all of a sudden will drop to 14-15% for a few second but will pick back up, pretty much does this EVERY time I start when the motor is cool, or has sat all night. While driving anywhere from 55-70 it usually stays around 50%, when warm and idling will stay around 70%. Any ideas as to why it will drop when first starting? Possibly sticking vanes? and Also are these percentages about the norm? Kinda thinking it wouldn't be a bad idea to clean the turbo
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Old 07-20-2013, 10:26 AM
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The duty cycles seem a little off. You could be seeing some surging of the wheel, but that is unlikely.

First question I have to ask is what strategy are you running? This plays a part in the initial start up cycle of 85% down to 15% and back - latest strategy from Ford does something similar (not sure of the specific duty cycles) as a measure to prevent sticking vanes - therefore some tuners have added the rotation in their tunes as well.

I see similar values though mine reads a little more open (1-3% compared to the values you gave).

Before you go tearing into the truck, what are your boost levels looking at during these changes of VGT duty cycle? It may be just the programming you have. Are there any other indications you have when you lose power cruiseing?
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Old 07-20-2013, 10:35 AM
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Could you explain what you mean by what "strategy" I'm running? I guess i should've gave some info on the truck as well. 2006 f250, 6 inch lift, 35's on 20's. bone stock except for straight pipe exhaust. As far as programming it isnt chipped or anything, i bought just the monitor, not the programmer/monitor duo. As far as boost levels, when crusining around 60-70 is around 8-10 psi. At idle 0. Other indications, the rpm drops just a touch along with the turbo psi when it skips. I also have the FICM voltage on display along with the vgt and the FICM never drops below 48 so its good
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Old 07-20-2013, 10:41 AM
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You should be able to pull up the truck's strategy on your Insight (this is something I do every time I take the truck into a dealer to ensure I haven't been re-flashed).
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Old 07-20-2013, 11:03 AM
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ECM: vxcf9h7
TCM: tqck0hz

Just went out and started it for the first time today, engine coolent temp about 95 degrees, go figure the vgt doesn't drop down to 15% like it usually does, at idle it stayed at 70%
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Old 07-20-2013, 12:45 PM
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My truck has the VXCF9 strategy stock. It "sweeps" the vanes on the turbo. If you let the truck idle for a few minutes you'll probably hear the exhaust note systematically change briefly. This is the sweep.

Why do you suspect the turbo is "skipping"? Generally if the turbo is at fault you will notice consistent symptoms and poor acceleration or heavy load struggling. I would run a buzz test and cylinder contribution test (or have ford do it) to ensure you don't have a fussy injector. But again, this is all completely a guess. Let us know some more about how the truck behaves. The more vague your post, the more vague our answer will be.

My VGT% are pretty consistent with yours.
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