Originally Posted by norbs |
I understand. I have given up on closed loop map mode it just does not react fast enough since the gate gate is at 100% duty cycle until the boost target is reached, this is just a bad design. No amount of PID tuning is helping the situation. We will be trying the analog * method next. The gate is too small for the car adding to the problem, However open loop we get no spikes.
I would make it a point to experiment further with closed loop analog 8. There are to many variables involved when trying to reliably control boost in closed loop mode.
1 - Back pressure(both intercooler and turbine)
2 - Wastegate size(Both area pressure is working against and flow capabilities)
3 - Wastegate springs
4 - Wastegate diaphram area
5 - Pressure source
6 - Solenoid response
7 - sensor response
When I look at my data logs using closed loop analog 8, it is trying to control boost indirectly by controling pressure on top of the gate. In my logs, the pressure on the top of the gate will start to be regulated before it reaches full boost. I believe this is the solenoid response you are looking for.
. Without honing in the PID, I only had about 1.5 psi spikes. My turbine was large compared to the compressor, therefor backpressure was low. My wastegate was also large but had a 20lb spring. With this set-up, I was able to achieve 35 lbs boost using only manifold pressure as supply pressure. Using CO2 would give instant pressure for faster response.