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problems with vr sensor

MoTeC M1 Software Tutorial

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we are fsae team and are using yamaha r6 engine. We destroyed our gearbox so we put in our spare engine which should be identical to our destroyed one so we can drive while we fix it. When we've changed the engines it had samo trouble starting but after a few tries it would start and run perfectly and after few days it has decided that it won't work any more. The old engine fired up very quickly. When it sensed the signal from the cam sensor it was in cycle lock. Cranking time was under a second. Car is in drivable state since spring and we were racing it this summer. I've done all wiring for the car and calibration and this is the problem I don't understand is it a wiring problem(have we touched something when changing the engines.) Wiring for the sensor looks visually fine. It's literally 20cm long so it's easy inspect. So to the problem. The new engine(this engine was running 2 or 3 years back on the old car but on different ecu) has some wired oscillations that the old one didn't have and motec won't get into cycle lock. Sometimes but with some extreme luck it fires up and then the signal from the sensor looks fine. We've also tried putting on a trigger wheel and sensor from the destroyed engine and no difference. New capture 1 is now and new capture 2 is from this spring. Also I have confirmed the signal form new capture 1 with an oscilloscope. It looks exactly the same(sorry I don't have a picture).




On the capture with the uneven speed, you can tell the engine slows down significantly twice per revolution. I would normally think this was each compression stroke. You might try removing the spark plugs and cranking -- the speed should be very even. If not, you have another issue. Perhaps you have an internal engine problem with a bent cam or chain pulley to the cam, or the piston is hitting the cylinder head or a valve (cam is mis-timed), broken valve spring, etc.

Looking at your package, if you have a hall-effect synchronisation sensor, you should just have a constant "Engine Synchronisation Pin Hystersis" value, probably 1.0V would be a good value. Also there is no reason to enable Engine Synchronisation Ignore Mode -- that is usually when using a MAP sensor for sync, which stops working when the throttle is opened and the RPMs increase.


yes the cam sensor is hall effect and crank is vr. I'm home for the holiday's but I will be back at uni next week. I will try out your suggestions. Do you have any suggestions on how could I change narrow and wide pitch threshold. It might help? I doubt there is something wrong with the engine internals. It did 200km since the last rebuild. I know we beat on them pretty hard but still the engine is very underpowered compared to stock. We have 90hp and 13000rpm limit compared to stock 120hp and 16500rpm limit. We usually destroy gearboxes. I've added a video(3 weeks old) of this problematic engine on google drive link. Once it starts everything is normal, same as the old engine. What puzzles me that those two engines that are supposedly the same do not behave the same. Maybe the cranking motor is dying. On the old ecu we had big trouble starting the engine for years with many different engines so maybe the cranking motor is destroyed.

Thanks a lot for your time


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