Tim M Posted May 26, 2023 Report Share Posted May 26, 2023 Greetings! We have a stockish Evo 5 with a Plug n Play ECU being remotely tuned. The tuner has been very receptive on the programs even though they haven't tuned this version of Link. We are getting close to complete, but boost control (boost cuts) are a bit challenging. Doing 3rd gear accels from 2500-7000 rpm, no issue. But if downshifting to 3rd from highway speed and going WOT results in boost 'cuts' due to it exceeding the preferred 23 psi although the boost/fuel cut is set at 26 psi. Why would it cut before hitting the threshold? Pic for attention! Really impressed with the ECU otherwise... Mitsubishi Evo 5 (Tim) V16.pclx Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 27, 2023 Report Share Posted May 27, 2023 All limits have a control range, the default for the MAP limit is 10Kpa. This means at 10Kpa below your set limit the "start cut" is applied, this is progressively ramped up to the "end cut" at your set limit. So the "Limit" is the absolute maximum that you never want to exceed, it is not the value that you want to start limiting at. Your MAP limit is currently set to 282kpa so limiting will start at 272kpa, this is about 24.8psi boost so if you are getting a cut it sounds like it is overshooting the 253kpa target by quite a bit. Will need to see a log to see the reason. Quote Link to comment Share on other sites More sharing options...
koracing Posted May 27, 2023 Report Share Posted May 27, 2023 I would add some stage 3 on delay time, and add more dervative to slow down boost ramp, but those are guesses without seeing the datalog of the issue. Quote Link to comment Share on other sites More sharing options...
Tim M Posted May 27, 2023 Author Report Share Posted May 27, 2023 Many thanks for the responses. Please see attached log...several accels with a boost/fuel cut in the middle. PC Datalog - 2023-05-25 8;49;43 pm.llgx Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 28, 2023 Report Share Posted May 28, 2023 Ok, a few things to change: Your boost control is dropping back to stage 1 during gearshifts, it should only drop back to stage 2 for a fast gear shift. Increase the deactivation timeout to about 0.4s. Add some stage 3 ON delay so that derivative can "put the brakes on" for long enough to stop overshoot before switching to stage 3. Around 0.3s is typical. Increase derivative gain. All of your gains are very low so closed loop isn't actually doing a lot in your setup, but derivative is typically way higher. More typical would be 2-20. You will prob want to increase integral clamp also as 2% doesnt allow the ecu much adjustment. Quote Link to comment Share on other sites More sharing options...
Tim M Posted May 29, 2023 Author Report Share Posted May 29, 2023 Adamw: Many thanks for the detailed response. I've passed the suggestions along! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.