2.8L Duramax I4 - VGT Surge

[rob_ddc]

Hi all,

I have a 2016 Holden Trailblazer with the 2.8L turbo diesel, there doesn?t seem to be a 4cyl GM diesel area so I?m posting here.

I am currently having an issue where there is a log of ?fluttering? on the VGT vanes when I?m at lower RPM and accelerating. In the logs I can see there is pressure and mass flow fluctuations which then stabilizes as the rpm increases.

I suspect the motor can?t ingest the volume of air the turbo can produce at this rpm so it?s causing the flutter, are there any tricks to smooth this out?

I?ve had a good look at the PID variables and am considering a small bump. Is there anything else I should check first or other strategies?

[Peasy]

Post a log of the issue.

[rob_ddc]

I've tried a few different things with the tune including capping boost to 280kPa absolute to ensure the MAP is in range, tried adjustments to the turbo PID and done some more tests. There does seem to be a big delta between the vane setpoint and actual and I'm leaning towards it being wastegate chatter. Keen for any suggestions.

For reference the car has an upgraded exhaust, intercooler and a Garrett PowerMax Turbo. It's a 2016 LWN with the E98 ECU.

I've also looked at the turbo compressor map and it's centre of the map so not where near the surge line.

One of the logs is attached.full throttle uphill.hpl