Quote:
Originally Posted by KoolBRZ
How on earth did you figure what numbers to use where? It transitions smoothly the way it is. Should I try using more than .7 at .2 and .3 load? How about using 1.0 PI only at .2 or .3 load in the low rpms?
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I am pleasantly surprised it worked. To be honest I plucked those numbers from my a@#. Few simple guidelines were followed
1. Going DI at low speed knock limited regions will increase volumetric efficiency and improve knock resistance
2. But going DI will make combustion slower so need to add more spark
3. The lower the speed the sooner the transition from PFI to DI because of same reason above.
4. Use PFI at loads that are not knock limited to improve fuel mixing and take advantage of faster combustion of PFI. This should reduce combustion variance and make engine feel more stable (less stumble)
5. Make sure to use 100% DI at the torque dip region
6. If it was upto me I would have tried 100% PFI at Idle. I think Toyota went for DI there for emission gains and to avoid knock during HOT RESTART. With PFI they need to model puddle dynamics when the engine is cold and other stuff. With DI they get better fuel control. I dont know if they are even going slightly lean at Idle for fuel economy reasons.
7. Going 100% PFI should also reduce the chirping??? I dont know for sure but worth a try. To really reduce chirping the fuel pressure must be dropped for DI at idle and then going 100% PFI. This is because even if DI isnt being used the pump is still working to maintain fuel pressure. Currently 24bar or 2.4mPa fuel pressure is commanded by the DI system at idle raising to 200bar pressure at WOT.