Hi guys,
I’ve been pretty quiet for a while and haven’t really done very much more than what I’ve posted. In fact, the car is actually back to stock since it went in for a service at the main dealer and I swapped from my modified ECU back to the original unmodified ECU (no problems encountered, just unplugged, swapped and cleared any fault codes).
However, I’ve been able to spend some more time on this over the last two weeks. Using IDA and the FR, I think I’ve located the following ram variables:
0x7FD71C pvdkds_w BoostPressureActual
0x80255C plsol_w BoostPressureSpecified
0x7FD830 nmot_w EngineSpeed
0x7FEE58 rl_w EngineLoad
0x80252E rlmx_w EngineLoadSpecified
0x802554 ldtv_w WastegateDutyCycle
0x80254E ldrkp_w LDR-control parameter for P component
0x80254A ldrkd_w LDR-control parameter for D component
0x80254C ldrki_w LDR-control parameter for I component
0x802546 ldptv_w LDR, duty cycle from the P controller
0x802548 ldrdtv_w LDR, duty cycle from the D controller
0x802544 lditv_w LDR, duty cycle from the I controller
0x80253A ldimn Current value for the minimum value limit I component LDR
0x802542 ldimx Current value for the maximum value limit I component LDR
Now even with the stock ECU, there is an initial boost overshoot as you can see in the graph.
(Sorry about the graph, I know it’s a very busy picture with a lot going on. RPM and Boost on left axis, P, I & D on right axis)
Also in the graph I’ve logged ldptv_w, ldrdtv_w and lditv_w. I wanted to see how the P, I and D components contribute.
Previously in this thread I’ve targeted KFLDIMX to clamp down on the initial overshoot. I think this is a bit unwieldy since I’m basically then running at the I limit?
What I’m going to try now is the Derivative component. In the graph I can see how it increases (gets more negative) until it reaches its most negative value just before the actual boost exceeds the specified boost. I propose to increase this so it’s larger (gets even more negative).
To accommodate the whole rpm range, I’m thinking of copying the entire row of values in KFLDRQ2 from row hPa=100 to row hPa=200 and then using new values in row hPa=100 (their value would be row hPa=200 plus 20%). Make any sense?
As always, comments appreciated!
