SES / Max Boost?
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Posting Guru
Joined: Oct 2003
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From: Tulsa, OK
SES / Max Boost?
My bone stock 2005 Excursion 6.0L throws the SES (Service Engine Soon) light when towing. I can't seem to get these codes from the ScanGauge II. What I am seeing is that there are 2 codes being output, I just cannot seem to read the codes using the ScanGauge II.
Also, when towing, I have been watching the MAP (manifold air pressure). It jumps into high 30s (psia) and then shows a number that is small (say 1.2). What I think is happening is that the display does not show numbers in the 40s.
So, assuming that my MAP is going to say 42 psia, this would make a boost pressure in excess of 27 psig. Is this reasonable? Or, am I getting the SES light because it is considered "overboost"?
The ECT and EOT readings are reasonable, so I don't think there is a problem with oil cooler / EGR coolers. What I suspect is that the turbo VGT is "sticking".
Should I tow with this rig or not? I'm supposed to leave Thursday for a 1500 mile tow through Texas.
Also, when towing, I have been watching the MAP (manifold air pressure). It jumps into high 30s (psia) and then shows a number that is small (say 1.2). What I think is happening is that the display does not show numbers in the 40s.
So, assuming that my MAP is going to say 42 psia, this would make a boost pressure in excess of 27 psig. Is this reasonable? Or, am I getting the SES light because it is considered "overboost"?
The ECT and EOT readings are reasonable, so I don't think there is a problem with oil cooler / EGR coolers. What I suspect is that the turbo VGT is "sticking".
Should I tow with this rig or not? I'm supposed to leave Thursday for a 1500 mile tow through Texas.
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
You should try to get the codes read. The low number of 1.5 psia is a vacuum at psig, which you should never see in a turbocharged engine. That would make me guess that there is a problem with your MAP sensor and you are getting sensor circuit codes.
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Posting Guru
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From: Tulsa, OK
But it is also curious that I am getting the SES light.
I guess the most important question is: what should the maximum turbo boost be when stressing a stock 6.0L under max load?
I guess the most important question is: what should the maximum turbo boost be when stressing a stock 6.0L under max load?
Lead Driver
Joined: Sep 2007
Posts: 8,180
Likes: 669
From: Scio, OR
I don't know if the check engine light will be set for an overboost, but I do think with the later PCM strategies at least a code will be set. I also don't know what is considered overboost, but I'm pretty sure it's higher than 27 psig.
Elder User
Joined: Sep 2007
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From: S CAL
I have seen my truck overboost before as high as 45 psi and have never recieved a code for it. The only time I have gotten a code for the turbo is a under boost. The normal range for max boost on a stock 6.0 L engine is around 25 psi to 29 psi. My truck at max boost is around 26 to 27 psi.
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Lead Driver
Joined: Feb 2011
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From: L.A. (Lower Alabama)
From the Tech Folder: The alarm is set for 28 psi boost stock and 30psi with a tuner, and engine is defueled at 28.6 psi.
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Thread Starter
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Posting Guru
Joined: Oct 2003
Posts: 1,198
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From: Tulsa, OK
What would make the boost go high? Stuck VGT blades?
Elder User
Joined: Sep 2007
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From: S CAL
That is a definite yes. I just pulled my turbo and cleaned it because of overboost and underboost problems with the turbo. It is now back to normal.
Elder User
Joined: Sep 2007
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From: S CAL
I have a boost gauge on mine that comes straight from the intake.
Hotshot
Joined: Apr 2010
Posts: 19,072
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From: Saratoga Springs,UT
the map gauge it comes with tops out at I think 37 psi absolute witch turbo charged diesels have no problem doing
read this thread
https://www.ford-trucks.com/forums/1...injectors.html
lots of great info here^^^^ you can program a x-gauge that will fix this and dial in your boost gauge its all in this thread