odoboyusa

actual boost seems to be related to the rpm. The higher the rpm, the higher the boost, even though requested boost is still at 980 mbar and load is very low.
What could be the problem? Diverter valves not opening or the N75 valve not working. What's even more weird is that it's not always doing it but it does it pretty frewuently and i am affraid of damaging the turbos.
I did not get any codes from the ecu... i discovered this by doing a log as preventive maintenance.
My engine is 2.7t with giac x chip.
Thanks in advance for any help!

4Driver4

Bad diverter valves and bad N75 will generally lead to lower boost rather than higher.

odoboyusa

but i will have to check tomorrow.
I think the n75 is working though because when boost works properly the actual and requested curves are pretty similar.
I will get back with the results.
Thanks for the help.

4Driver4

Diverter valves only open when the throttle is closed.

odoboyusa

be able to operate them whenever boost was needed or not, depending on load not on throttle position.
Here's some info from the log:
rpm load req act req act
mbar mbar psi psi
720 18 980 990 0.0 0.1
720 18 980 990 0.0 0.1
720 18 980 990 0.0 0.1
800 23.3 980 990 0.0 0.1
760 32.3 980 990 0.0 0.1
840 34.6 980 990 0.0 0.1
920 37.6 980 990 0.0 0.1
1000 33.8 980 990 0.0 0.1
1040 40.6 980 990 0.0 0.1
1080 51.9 980 990 0.0 0.1
1160 57.1 980 1000 0.0 0.3
1320 67.7 980 1010 0.0 0.4
1520 72.2 1020 1050 0.6 1.0
1680 70.7 980 1100 0.0 1.7
1880 69.2 980 1140 0.0 2.3
2040 65.4 980 1180 0.0 2.9
2200 54.9 980 1180 0.0 2.9
2080 14.3 980 1100 0.0 1.7
1600 12 980 1040 0.0 0.9
1520 32.3 980 1010 0.0 0.4
1480 48.9 980 1030 0.0 0.7
1520 48.9 980 1040 0.0 0.9
1320 17.3 980 1030 0.0 0.7
1040 18.8 980 1010 0.0 0.4
920 19.5 980 1000 0.0 0.3
840 18.8 980 1000 0.0 0.3
760 18 980 1000 0.0 0.3
720 18 980 990 0.0 0.1
720 18 980 990 0.0 0.1
720 18 980 990 0.0 0.1
720 18 980 990 0.0 0.1

this one is one of the weird parts...where boost starts rising without it being requested. There are worse sections, i just found this one that is really obvious.
Thanks!

n1mr0d

i don't think that 200mbar is enough to worry about, but consider logging the N75 duty cycle

odoboyusa

There are larger pressures present when request is 0... which block for n75 duty cycle?

Ming 2.7T

can you post the 115 excel file.

odoboyusa

How? I don't know how to attach a file. I will attach it if i can...

4Driver4

This prevents the rush of boost from slamming into the suddenly shut throttle and stalling the turbo. They basically are they for turbo longevity and anti-lag. They and vacuum operated and do not regulate boost under throttle.

The N75 regulates boost under throttle and is controlled electrically via the ECU.