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Rob Humphris - Cambridge, UK. http://www.vems.co.uk ---- '''VEMS Wideband Guage Question''' I have been asked about the effective operating range of our Wideband system: What level of accuracy does it provide for ethanol fueled engines? No real idea on the accuracies, but very interested in the results! I intend to power the TVR on ethanol eventually. http://wbo2.com/lsu/ Reading through the above link, I'd guess that the sensor has more-or-less the same accuracy whatever the fuel. The sensor measures free oxygen in the exhaust gas, so is measuring actual lambda not the AFR directly. The difference is a lambda of 1 no longer represents an AFR of 14.7:1 - ethanol is approximately 7:1 if my memory is OK. So, presumably there's an ideal AFR divisor parameter in the wideband code on VEMS. This needs to be changed from 14.7 to whatever is required for ethanol. It's the same order of magnitude (give or take) so shouldn't affect the calculations. Incidentally you can get some kind of specific gravity sensor for fuel tanks now. This can be used to decide what fuel is in the tank (or indeed what mixture of fuels is in the tank). Maybe there could be a lookup table built in to VEMS that changes the AFR parameter so that the car can be multi-fuel capable. That's my plan (if I can get it to work - there are many other engine issues to cope with too) anyway... Hope this is sane and that it helps dnb ---- '''Currently Developing''' UsabiLity UsabiLity/GenBoard/WinTools PIDControlTuning MembersPage/PhatBob/UserGuide MembersPage/PhatBob/ToyotaFitting MembersPage/PhatBob/Marketing VehicleFitment/Toyota VehicleFitment/Honda VehicleFitment/Nissan ---- MembersPage/PhatBob/MagnettiMarelliSensorProblem MembersPage/PhatBob/PurchasePage MembersPage/PhatBob/ConfigProblem ---- The closing times are also needed (it is the function of injector current and flyback voltage). The flyback voltage actually makes a huge difference. The opening times are not (by far) enough to calculate GenBoard/Manual/Config/InjectorOpening parameters. You can start from other's values, make sure * injopen=00 (or very very short for low-voltage flyback, max 100 usec) * battfac=10 (256..700 usec is usually OK) * injocfuel=2C (500..1200 usec usually) * injrampup_battfac=FF (IIRC 4082 ... in MegaTune, it does not have a simple physical unit like "usec" or similar) ---- http://vems.hu/www.vems.co.uk/VEMSWB/VEMSlcdDark.jpg http://vems.hu/www.vems.co.uk/VEMSWB/VEMSlcdLight.JPG http://www.pgmfi.org/twiki/bin/view/Library/EcuSensors ---- v3.2 Assembly documentation: v3.2 How-to power-up a new board. http://vems.hu/www.vems.co.uk/VEMS/ ---- In an attempt to document my installation: * GenBoard/InstallPage/PowerUpToBootloader For UsabiLity to be more useable studies like this are of interest. http://www.useit.com/alertbox/reading_pattern.html
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