29-01-2014, 07:02 PM
Commonrail can be even quicker to respond than XUDs if the map is adjusted for it... Petrols are adequately responsive - remember they require the manifold to fill with air, it go past the valves, takes quire a few strokes for that to happen...
Commonrail on the other hand polls the tps at say 1kHz, that's one THOUSAND times a second, the ECU runs at 25MHz and has very efficient code... That means the engine at 6000rpm is requiring 100 injection events per second, across all cylinders... So yeah, the pedal even at 1kHz is being polled for data 10x faster than the fastest opportunity to change the injection quantity... And that's a very, very simple equation which is near enough pointless other than to show the difference between how fast the ECU is working vs how fast the engine is working...
But yeah, the ECU can quite easily change injection quantity on a per stroke basis... There's nothing stopping the ecu responding near instantaneously... Just the hysteresis on the map...
Commonrail on the other hand polls the tps at say 1kHz, that's one THOUSAND times a second, the ECU runs at 25MHz and has very efficient code... That means the engine at 6000rpm is requiring 100 injection events per second, across all cylinders... So yeah, the pedal even at 1kHz is being polled for data 10x faster than the fastest opportunity to change the injection quantity... And that's a very, very simple equation which is near enough pointless other than to show the difference between how fast the ECU is working vs how fast the engine is working...
But yeah, the ECU can quite easily change injection quantity on a per stroke basis... There's nothing stopping the ecu responding near instantaneously... Just the hysteresis on the map...
