martinlink
Well-known member
Hi!
Still trying to get the car dialed in. It's a BMW E46 320d 150hp, 2.0 litre common rail straight 4.
Turbo: Garrett gt1749v with Melett internals, VNT gen 1, vacuum actuated
ECU: Bosch EDC16C31
Mods: full decat (both cats emptied), EGR delete with blank on exhaust manifold, remap.
The problem:
The turbo was refurbished and the stop screw and actuator rod length were set through trial and error by me so that with the stock tune everything was great - quick spool, no over/undershoot.
After applying the tune, it started spiking very mildly, followed by a big dip in boost and IQ. N75% does not follow N75 pre-control maps (neither regular or transient) so it must be the PID taking over in closed loop mode.
I've put it down to the free flowing exhaust and increased fueling with the tune, and I think it's the PID that is a bit too spastic, reacting to the quick rise of boost by dropping N75% a bit too much.
I have tried to reduce the PID factors around the spike and this has resulted in a smoother N75% (just a little bit) in 3rd but 4th is still pretty erratic.
Here are the graphs in 3rd and 4th gear, WOT:
Green line is N75 duty factor (scale on the right side). I can also provide the .csv logs and the tuned and original files if anyone could take a look at them
The question:
Does this look like a too short actuator rod? Or a problem with the boost request vs actual deviating too much for too long, causing the PID controller to go ham on the pre-control maps?
Should I try lowering requested boost before 1800rpm to try and calm down the PID?
Any input is very welcome!
Still trying to get the car dialed in. It's a BMW E46 320d 150hp, 2.0 litre common rail straight 4.
Turbo: Garrett gt1749v with Melett internals, VNT gen 1, vacuum actuated
ECU: Bosch EDC16C31
Mods: full decat (both cats emptied), EGR delete with blank on exhaust manifold, remap.
The problem:
The turbo was refurbished and the stop screw and actuator rod length were set through trial and error by me so that with the stock tune everything was great - quick spool, no over/undershoot.
After applying the tune, it started spiking very mildly, followed by a big dip in boost and IQ. N75% does not follow N75 pre-control maps (neither regular or transient) so it must be the PID taking over in closed loop mode.
I've put it down to the free flowing exhaust and increased fueling with the tune, and I think it's the PID that is a bit too spastic, reacting to the quick rise of boost by dropping N75% a bit too much.
I have tried to reduce the PID factors around the spike and this has resulted in a smoother N75% (just a little bit) in 3rd but 4th is still pretty erratic.
Here are the graphs in 3rd and 4th gear, WOT:
Green line is N75 duty factor (scale on the right side). I can also provide the .csv logs and the tuned and original files if anyone could take a look at them
The question:
Does this look like a too short actuator rod? Or a problem with the boost request vs actual deviating too much for too long, causing the PID controller to go ham on the pre-control maps?
Should I try lowering requested boost before 1800rpm to try and calm down the PID?
Any input is very welcome!