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MoTeC M150 GPRP-based FW shifting problems

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I'm having some trouble getting engineering support, so I thought I'd try and see if anyone here might have some insight. The car is a Radical SR8 with a MoTeC M150 using RDS custom firmware (based on GPRP). The gearbox is a Hewland JFR201, and it has a complete Geartronics hardware system (compressor, accumulator, actuator, etc.)

The car upshifts perfectly except when the driver hits the engine redline before attempting to shift. Data analysis shows that good upshifts have spark reduction, and failed upshifts don't.

I'm wondering if the issue is caused by the firmware prioritizing engine speed management (via spark) over requests to cut spark to reduce torque to allow an upshift. In other words, the very thing that would reduce engine speed (an upshift) is being ignored because engine speed management is engaged.

Thoughts, anyone?

Many thanks!

Seems to make sense if the retard on shifts reduces rpm and load, but the limiter is holding it against the limit.

Don't know the system, but there may be an option to change the ECU priority so the conditions are reversed?

Interesting. I've been looking through the shifting parameters... I'll have a look at the engine speed limits, thanks.

It's clear in the data: when the ECU gets into an Ignition Cut Mode of Engine Speed, it ignores the Ignition Cut Request of Gear Shift. The only "fix" I can see is either: 1. Reduce throttle, and try again, 2. Keep pulling the paddle and hope the dogs release enough to get out of gear (and enough to get into the next gear), or 3. Shift before hitting the engine speed limit.

I don't see any way to have a Gear Shift cut request override an existing Cut Mode for Engine Speed.

Hello John,

In the Standard MoTeC GPRP firmware, there are multiple Engine Speed Limits (maximum, from warnings, pit limiter, traction control) as well as a Gear Shift Engine Speed Limit used to match revs on both up and downshifts. So the primary torque / rev reduction on an upshift comes from setting a temporary rev limiter to the engine speed needed for the next gear. The Standard firmware picks the lowest of all Engine Speed Limits, and this is the channel "Engine Speed Limit" and the channel "Engine Speed Limit State" will identify what limit is active.

Looking at the Geartronics package (I have a customer using this on an M150), I see they have an Engine Speed Limit setup in Geartronics Shift Up Cut Stage 3 Engine Speed Limit. You might see if that is setup / in use.

I think your question can only be answered by someone with access to the Geartronics Firmware Project. Have you tried contacting Neil at Geartronics?

As a workaround, I suggest you consider using Auto Up Shift and setting that to just below the Engine Speed Limit Maximum.


As always, many thanks! Neil sent me to the Geartronics Rep for North America, who was quite responsive and helpful during the initial installation and tune. I'm quite happy with its operation as it's been an improvement over the generic GPRP I ran before. However, I've been trying to get his help on this particular problem for a long time now, without success. Hence this post.

Back to the data, the actual limit in place during the missed gearshifts is "Engine Load", which is set the same as the overall Engine Speed limit. Looking at the Up Shift Cut Stage 3 Engine Speed Limit parameters: I think you're on to something. I see values of Power On RPM target of 90%, Power Off RPM Target of 110%, Ignition Range of 1 RPM, Fuel Margin of 1 RPM, and Fuel Range of 1 RPM. I'm posting links to my tune and log if you have interest / time.

Tune/Package: [color=black]https://www.dropbox.com/t/FVVqeFc0A1NY7gmE[/color]

Log: (missed shifts at about 8:40): [color=black]https://www.dropbox.com/t/UBewPykW9LjrnC4H[/color]

And finally, yes, good idea, I'll enable Auto Up Shift.

Unfortunately, the files you provided were not useful. To share your package, use M1 Tune File->Open Package... and then the "Export File..." icon in the Open Package window. This will export an archive file that is easy to move to other computers and install in M1 Tune with just a click. The Logged Data file may have contained a copy of the Package within it, but you have provided the .LDX (index) file, and I would need the matching .LD file.

Check the parameter "Geartronics Shift Up Cut Stage 3 Mode". I think that if that were set to "Engine Speed Limit", then a lower Engine Speed Limit would be provided when you attempted an upshift with a Speed Limit Cut active. I'm betting it's set to "Standard Cut".

Sorry! See below for a better link to an m1pkg-archive file.

Anyway, you're right: Shift Up Cut Stage 3 Mode is set to Standard Cut. If I want to change that to Engine Speed Limit, what sort of values would your recommend for Ignition Range, Fuel Margin, and Fuel Range?

Package / archive: [color=black]https://www.dropbox.com/t/RJJWCWmlN7PqkiX8[/color]

I think what you had was a reasonable starting point.

Excellent, thanks!

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