2017 2.7L Boost Pressure
10-04-2017, 04:10 PM
#1
Senior Member
Thread Starter
2017 2.7L Boost Pressure
Finally had a chance to monitor boost pressure while driving the truck and thought I’d post my findings.
As monitored by the onboard boost pressure sensor 27psi in 1st gear, 33psi in all other gears.
Of note: The pcm also makes desired boost pressure available. The desired boost pressure at idle is 12psi. As throttle position increases so does the desired boost pressure. However, the desired boost pressure increases gradually but quickly in 1st gear. It’s also somewhat gradual but closer to instant in 2nd and beyond.
I was also able to monitor the waste gate duty cycle. This is certainly (and obviously) where the tunes are finding additional power as the pcm is clearly holding back boost pressure under many circumstances.
What does Ora this mean to you? Probably nothing but I still found it worth sharing. 30psi is quite a bit and much more than I expected.
As monitored by the onboard boost pressure sensor 27psi in 1st gear, 33psi in all other gears.
Of note: The pcm also makes desired boost pressure available. The desired boost pressure at idle is 12psi. As throttle position increases so does the desired boost pressure. However, the desired boost pressure increases gradually but quickly in 1st gear. It’s also somewhat gradual but closer to instant in 2nd and beyond.
I was also able to monitor the waste gate duty cycle. This is certainly (and obviously) where the tunes are finding additional power as the pcm is clearly holding back boost pressure under many circumstances.
What does Ora this mean to you? Probably nothing but I still found it worth sharing. 30psi is quite a bit and much more than I expected.
10-04-2017, 06:06 PM
#2
Senior Member
The sensor is also reading atmospheric pressure. You will have subtract the atmospheric pressure from the boost readings. At Denver's altitude 12psi for atmospheric pressure so at idle the boost is actually 0psi.
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chimmike (10-04-2017)
10-04-2017, 06:36 PM
#3
Senior Member
Finally had a chance to monitor boost pressure while driving the truck and thought I’d post my findings.
As monitored by the onboard boost pressure sensor 27psi in 1st gear, 33psi in all other gears.
Of note: The pcm also makes desired boost pressure available. The desired boost pressure at idle is 12psi. As throttle position increases so does the desired boost pressure. However, the desired boost pressure increases gradually but quickly in 1st gear. It’s also somewhat gradual but closer to instant in 2nd and beyond.
I was also able to monitor the waste gate duty cycle. This is certainly (and obviously) where the tunes are finding additional power as the pcm is clearly holding back boost pressure under many circumstances.
What does Ora this mean to you? Probably nothing but I still found it worth sharing. 30psi is quite a bit and much more than I expected.
As monitored by the onboard boost pressure sensor 27psi in 1st gear, 33psi in all other gears.
Of note: The pcm also makes desired boost pressure available. The desired boost pressure at idle is 12psi. As throttle position increases so does the desired boost pressure. However, the desired boost pressure increases gradually but quickly in 1st gear. It’s also somewhat gradual but closer to instant in 2nd and beyond.
I was also able to monitor the waste gate duty cycle. This is certainly (and obviously) where the tunes are finding additional power as the pcm is clearly holding back boost pressure under many circumstances.
What does Ora this mean to you? Probably nothing but I still found it worth sharing. 30psi is quite a bit and much more than I expected.
10-04-2017, 06:46 PM
#4
Senior Member
Thread Starter
Possibly, and a good observation. When I have the time again there is a wealth of information available in the pcm live data that I could use to verify this. 12psi was the desired boost pressure at idle and was being held there via the waste gate duty cycle. So while you are correct that atmospheric pressure may come into play, it also indicates that the turbo pressure is needed to be controlled even at idle.
Regardless, there is much computer intervention happening with boost pressure at all times and much of it available. That was the point of my post. Hopefully I will soon have a 3.5T test mule to compare it to.
Regardless, there is much computer intervention happening with boost pressure at all times and much of it available. That was the point of my post. Hopefully I will soon have a 3.5T test mule to compare it to.
10-04-2017, 06:49 PM
#5
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Join Date: Mar 2017
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I used an old phone and installed obdlink app and connected to obdmx tool I use with forscan.
First gear peaked at 9 psi
Second peaked at 15 psi
To much traffic at the time to check other gears but I will later.
BTW. My truck runs great and the butt dyno says it is a lot more fun to drive than the 5.3 chevy I traded in.
First gear peaked at 9 psi
Second peaked at 15 psi
To much traffic at the time to check other gears but I will later.
BTW. My truck runs great and the butt dyno says it is a lot more fun to drive than the 5.3 chevy I traded in.
Last edited by KWS 2.7; 10-04-2017 at 11:47 PM.
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10-04-2017, 07:55 PM
#8
Senior Member
27 - 12 = 15 psi
33 -12 = 21 psi
Most likely scenario is 15-20 psi.
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ralphsmithiii (10-04-2017)
10-04-2017, 07:58 PM
#9
Ah ok, that makes more sense to me. I didn't see it in the original post but I'm guessing that's not stock?
My interest is this is that I'm seeing 17.8 WOT in sport mode on a 15 with a 93 Per/Tow 5* setup, although I just made the change. I'm not sure what these trucks make stock although I'm considering testing it to see the actual delta.
My interest is this is that I'm seeing 17.8 WOT in sport mode on a 15 with a 93 Per/Tow 5* setup, although I just made the change. I'm not sure what these trucks make stock although I'm considering testing it to see the actual delta.
10-05-2017, 05:53 AM
#10
Mine actually ran better, more torque coming up the mountain grades than on the level (much lower altitudes) it seemed Monday, the higher we climbed the better she performed. Lol