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Post Info TOPIC: Clutchless shifting, shift cut - can it be implemented in ECU ... easily ?


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Clutchless shifting, shift cut - can it be implemented in ECU ... easily ?


I have started to think about getting a shifter, i.e. shift cut to allow clutchless gear shifts. All the products I know turn the FI light on, so come to think about building this feature into ECU.

The initial concept could be based on the following:
- The clutch signal activates a shift cut function
- Shift cut function turns off the ignition or injection for 35ms (or any other adjustable number)
- After the cut limit (eg 35ms) is reached, then the normal clutch limiter is activated until clucth switch state is returned back to normal - ie gear on.

I think that implementing this should be fairly easy. As the clutchless shifts really are interesting only between 8-12krpm I would guess that we could just deactivate the ignition or fuel for 3-5engine revolutions to get the desired effect ?

Any comments or ideas about this ? Interested in helping to implement ?



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it's an great idea, keep us turbo guys in mind as cutting fuel for us is not a very good idea...ignition would be much safer.biggrin 

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it's an great idea, keep us turbo guys in mind as cutting fuel for us is not a very good idea...ignition would be much safer.biggrin 



Dont know - we have had a few valves destroyed because of ignition shift cut being timed just a bit too long. The reason being the fact that fuel goes into the engine and autoignites, sometimes on the exhaust side and the valve pops coming out from retainer.




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I've been using a Bazzaz Z-Fi TC that includes a shifter, and it does not activate the FI light on my GSX-R1000K5. I would think that, as long as the ECU senses a load that's equivalent to that of the coil during the cutout period, that an error code would not be generated.

Note that the cut time varies with gear position from 80ms to 40ms.

Instead of the clutch switch, I have used a relay hooked up to the horn button to make my own cheapass shift cutout systems before. No need to use the ECU for this simple setup. However, if you're going to go to the trouble of having gear-specific cut times, it would be nice to have the ECU handle current gear identification, as well as ignition cutout, but I'm not sure how you'd program the logic for the cut times into the ECU. Also, using a switch that senses load on the shift linkage would be much more accurate than a clutch lever switch, especially if you're talking about a 35-40ms shift window.


-- Edited by tcchin at 09:05, 2008-05-26

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I think we must clarify one thing here...

The clutch switch allows an input signal to ECU - the actual sensor should be always a load sensing device in the gear lever.

The strategy I am thinking to try out first is to use the clutch limiter for 3-5 engine revolutions and then return back to normal limiters. Using this method you can choose which limiter (fuel or ignition is used) and implementing the subroutine should be fairly straight forward. Its also possible to have a simple timer giving the 30-50ms signal to ecu - but as a prinsiple its to utilize clutch limiters and maps.

(The older ecus were not so sensitive about cutting the signal as the new ones.)

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