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Junior Member
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Discussion Starter #1
I have a 2006 Ford F-350 6.0 automatic with 100,000 miles on it, the engine is bone stock and runs good, my question is:
While driving at a steady speed, on let's say interstate highway at 65mph my boost gage(factory stock)will very from 5 to 10 while holding the throttle steady. Is this something I should be concerned about.
 

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149 Posts
when do you notice it? is the truck accelerating up an incline on the highway that you may not seem very noticable?
 

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Stuck in Commiefornia...
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Could be the unison ring in the VGT turbo is sticky or worn and the actuator is slowly compensating back and forth. Mine had a turbo at 85k for shaft play and a worn ring.
 

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Discussion Starter #4
when do you notice it? is the truck accelerating up an incline on the highway that you may not seem very noticable?
The boost gage varies at a steady speed running on level surface, I can understand the boost changing under a pull, but it will increase and decrease under a steady throttle on a smooth flat highway.
 

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1,324 Posts
Be good to pick up a scangauge and see if the Vgt value is changing and if the scangauge Xgauge for boost agrees with the stock reading. I believe both are inferred values. I have a true pressure boost gauge since I don't have one stock. If the turbo us sticking it can be cleaned and/or unison ring replaced.
 

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Is this while the grade is changing? Are you going up and down hills?
For small changes in grade mine varies a bit.
If it's on flat ground or a hill where the grade is not changing (for example a consistent grade up or down) it should not vary too much.
 

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Senior Member
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First I would check your air filter and check and clean your egr valve, then check all your intercooler intake boots for any tears or spilts....both items can effect boost readings and egr is most active at steady cruise speeeds...these are easy items to check and eliminate as possibilities.

Could very likely be your variable gate turbo vanes as Idaho mentioned too...very common.

What is your max boost under heavy throttle?...Should be minimum of 26psi.

Definitely recommend the ScanGaugeII as Weld mentioned.

Also any high pressure oil system leakage could cause the boost readings to fluctuate too, as fuel delivery will be unsteady and it can effect boost.

Again, recommend the ScanGaugeII, as you can read / ICP / IPR / FICM main power / Turbo vane position / and much more.

Harry
 

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Just to add...and Idaho is probably right on this one...I road tested an 06' 6.0L with a fella I know yesterday that is experiencing the same boost variations at steady cruise speed on flat freeway...his ScanGaugeII VGT reading would jump around and be reading 53-58% then drop to 25-35% then back up again to 63% as the boost gauge was fluctuating, the whole time ICP and IPR were holding steady as was his vehicle speed.

We then jumped in my truck and drove the exact same route and speeds...my VGT would lock and hold perfectly steady at around 43% and my AutoMeter boost gauge was steady as a rock.

I'm thinkin turbo vanes are sticking too in this case.

Harry
 

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Discussion Starter #9
Thanks everyone for the info.
 

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Junior Member
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not to high jack your thread Eddie, but would sticking turbo babes cause the VGT to cycle when idling? when my truck idles you can hear the pitch of the exhaust time change like the vanes in the turbo cycle open and closed.
 

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not to high jack your thread Eddie, but would sticking turbo babes cause the VGT to cycle when idling? when my truck idles you can hear the pitch of the exhaust time change like the vanes in the turbo cycle open and closed.
The exhaust tone changing is the vanes moving back and forth in stages...this is a normal programming feature that most trucks have. By cycling the vanes back and forth at idle it helps keep carbon build up minimal and the vanes freed up.

The turbo also needs to be relearned if this feature loses it's calibration, by say changing the batteries or unplugging the ECU.

To relearn the turbo...clear all fault codes twice, even if there isn't any....run engine up to operating temperature and let it idle for 10-15 min.

Most ECU programming has this feature now, even my custom tuning does too, it's good to have.

Harry
 

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33 Posts
I had this also happen to my truck its sometimes referred to as boost spikes. Mine was caused by the boost sensor tube being plugged with soot. I barley blow any black smoke and this happened. It was a very easy fix just remove the tube it runs off the passenger side of the intake manifold. up to the sensor kinda buy the heater core line. Take it off blast some brake cleaner down it and clean the sensor end where the tube connects. A tuner with a boost gauge with smaller increments will help you see if you have helped fix the problem. If so you might need to pull your intake manifold and clean it as well as the egr. Hope this helps.
 
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Junior Member
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I had this also its sometimes referred to as boost spikes. Mine was caused by the boost sensor tube being plugged with soot. I don't blow barley and black smoke and this happened. It was a very easy fix just remove the tube it runs off the passenger side of the intake manifold. up to the sensor kinda buy the heater core line. Take it off blast some brake cleaner down it and clean the sensor end where the tube connects. A tuner with a boost gauge with smaller increments will help you see if you have helped fix the problem. If so you might need to pull your intake manifold and clean it as well as the egr. Hope this helps.
 

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Stuck in Commiefornia...
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The EBP sensor and tube on a 6.0L is located on the driver side exhaust manifold and can easily be reached for service by removing the air filter and ducting. The tube has a small clamp holding it to the FICM bracket and is a simple glare nut at te bottom.

7.3s have the EBP sensor on the passenger side.
 

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If Idaho is that sure about it I would go with what he said its been awhile since I've had to clean mine and didn't look under the hood before posting.
 
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