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Does anyone know if it is possible to utilize the gear shift feature on the M1, perhaps with a bit of trickery, to blip the throttle for down shifts on a standard H pattern car?
I find it surprising this doesn't seem to be an easy feature to simply enable using a clutch and brake input along with some engine speed and throttle targets. Even some of the less advanced ECUs offer this, not to mention Ecutek for example has created patches for cars like the FT86 to allow this on the stock ECU using basic available inputs.
Looking at M1 Tune, it seems like we might be able to get it working possibly but only by working around some limits and using inputs in unintended ways. For starters, under Gear type, the help info notes "When set to H Pattern, all shift requests are considered to be up shift requests" so right away, we'd seemingly have to tell the M1 we have a sequential box even when we don't. Then, for a shift lever input, it seems like we could use the brake pedal as a shift down request switch to trigger the throttle aim value for a defined duration but only if the clutch is also being pressed by enabling clutch lockout but inverting the clutch input so that when you clutch in, the ECU see's this as engaged to allow the blip but when the clutch is not pressed, it sees clutch state as disengaged to prevent the blip. Obviously you'd also have to disabled clutch lock out for the starter if you invert your clutch input.
Now it seems like doing this could in theory provide a throttle blip when the brake is pressed and then you clutch in to clear the lockout BUT what I don't know until I get a chance to test this (M1 is on the way) is if the downshift request will be immediately ignored if the clutch lockout is active or if it remain in a requested state and be fulfilled when the lock out is cleared, ie, you press the clutch after you've gotten on the brake. The diagnostic delay could be extended a lot to allow being on the brake pedal as long as needed, ie, requesting the down shift, but I don't know if it will wait for the clutch to be pressed or not.
The other "issue" with this concept would be that you'd only get one blip unless you come off the brake and back on it for a 2nd gear change. That likely wouldn't be feasible threshold braking into a corner and needing to go down more than one gear but still having at least one easy gear change or having this for situation where you only need to go down one gear would still be better than nothing.
Curious to hear any input on this subject or perhaps the Andre can test this out on their FT86 M1 project car and let us know if it works or not :)
The challenge is determine if the driver is requesting an upshift or a downshift, and when that shift is complete. With a sequential gearbox and a strain gage (or a pair of switches), the ECU can determine this pretty easily, and handle the 4 basic conditions (Upshift Power On, Upshift Power Off, Downshift Power Off and Downshift Power On).
So from your description you would like to only handle the two basic cases (Upshift Power On, and Downshift Power Off), and do that using conditions like:
Upshift is requested when vehicle is moving and Throttle > Power On Throttle and Clutch is Disengaged.
Downshift is requested when vehicle is moving, Brake is active and Clutch is Disengaged.
You could build a simple table of timers for Ignition Cut on upshifts, and Throttle target aims on downshifts. This would be the similar to what Ecutek do, I believe. That is not nearly as sophisticated as what the M1 does with closed loop termination of the timers when the new gear is reached, but you might be able to implement the rev-matching with the Gear Shift Engine Speed Limit.
I say get M1 build and go for it. I think it's a harder problem than you may think, but if you want to make it happen, M1 build is the way to do it.
From memory, Nissan had throttle blip on the 370Z with an H-pattern. You may have luck reading some of their forums to see if someone has reversed engineered their algorithm.
I actually only want to handle downshift power-off. I simply want to be able to be threshold braking, ie, really needing to modulate brake pressure with 100% focus from my right foot, and have the ECU handle blipping the throttle as I clutch in so I can downshift while threshold braking into a corner. I can heel-toe decently but not as clean and consistently as an ECU could do it for me. This is what I am looking for.
In the future I'd like to invest in M1 build and start building out features like this but for now, I am looking to utilize what's available in the GPR package.
I've spend more time looking at it and I am pretty convinced it can be made to work but not the way I laid out. I believe the brake can be used as a downshift trigger but if the clutch is used as a lockout, the downshift request when you press the brake will be ignored, even you if then press the clutch. I don't think the downshift request will wait for the lockout to clear.
I did think of another simple way I might be able to do this by using a couple relays. The first relay would work off the brake switch and connect to a second relay on the clutch switch. When pressing the brake and the clutch, the 2nd relay could generate a simple voltage signal to the ECU into an input that could be tied to a driver switch that could then be used for a down shift request. You'd simply use the rpm limiter and the throttle aim and blip duration tables to control the blip when requested. In theory, you could get a blip per clutch engagement so you could accomplish multiple down shifts while braking into a corner. This is what I am going to try if the first method doesn't work.
The Nissan 370Z uses two gear position sensors, mounted towards the shifter itself. So the ECU knows the axis in which direction the shifter is beeing moved and therefore can blip the throttle.
I have yet to find the time, to do some testing on our Syvecs unit with that setup.