Motec M1 GPR Idle Integral Wind-up

Aloha guys, first time posting but long time lurker. Quite honestly I am usually able to find any info I need on here already( this place is such a gold mine) so never had much of a need to start a thread but I haven't been able to find an answer to this little issue I have. I am working with a GPR custom firmware for a C6 M6 corvette but I believe this is applicable to all GPR packages. I am having an issue with wind-up whenever I am downshifting without throttle input\engine braking and revs drop below the Idle threshold (so essentially low vehicle speed downshifting like coming to a stop light), this causes the car to stall due to the ECU trying to pull airflow to control idle speed.

Example: Driving in 3rd gear rpms around 1500, when downshifting into 2nd rpms fall below idle threshold due to clutch input thus entering idle mode, release clutch and rpms now jump up to 1800-2000 and engine braking. Integral starts to pull airflow because computer still thinks car is trying to idle due to no throttle input and reaches its integral min limit along with ignition timing following suit. This causes some popping from exhaust and if I press clutch in the car will stall because there's not enough time for the controller to recover.

In any other scenario, idle controller works perfect. Idle Mass FF is dialed in, idle is rock steady and returns to target as expected with no over\undershoot

Other ecus along with OEM stuff typically have some kind of Max Idle RPM or Max Veh Speed for Idle tables to combat this but I cant for the life of me figure this out on the M1 software. What am I doing wrong here? I am relatively new to the Motec platform (only done a handful of cars so far) but not new to tuning

I've tried to attach my latest revision of the package but says I cannot load a "Null" file? I appreciate any input anyone can give me on this

-Al

You need to set Idle Mass Flow Integral Minimum to a suitable number so it doesn't reduce your Mass Flow % too low in these conditions.

This is an interesting case you've identified.

My first thought was that perhaps Idle Aim Ramp Down Limit was too high. Also, do you have Engine Overrun enabled? -- that can provide some control over entering idle control (like Engine Overrun Vehicle Speed Threshold), and can go into the Retard Ignition state when a gear shift is processed.

Since it seems like this is a street application, and you are already using custom firmware, you could add a "clutch lockout" feature that exits idle mode if the gear is not neutral and the clutch is engaged (and the Engine Speed is greater than Idle Aim Main + Idle Aim Compensation).

BTW -- this would be a good topic to post on the MoTeC support forum (https://forum.motec.com.au/)

Hi guys, thanks for the replies..

Scott, I have it currently set to a limit of -10% but have tried at -5% limit with same affect, though nothing smaller than that as it seemed to me be too narrow of a window, I may be wrong here

I have tried slowing\speeding up PID controller gains on both the P and I with no real improvement and essentially just causing random instability.

David, I have seen your name a lot on here so I appreciate your time. I have played with Idle Ramp anywhere from 150-500rpm with varying decay rates.

I did have overrun enabled for a little while but problem persisted and would have a real small "hiccup" anytime it exited overrun and did not find any adjustments for re entry fuel\timing so I disabled it to preserve driving manners.

Its a custom firmware by another developer who has not been very helpful with another bigger concern I have had with this firmware so I doubt they will be willing or receptive to add this functionality for me regarding a clutch lockout feature. Unless there is a way for me to manipulate these kind of parameters in build? Again I am newer to this platform so if there's other options I am all for it.

I will cross post this as well on the Motec forums, thats a great idea.

Thanks much!