[amnonholland]

All, I have been doing some experimentation with variable displacement as described below. So far it's worked from a technical point of view but can't validate fuel economy with mpguino as this mod cuts inj pulses. One unexpected gain has been an improvement in throttle response/ pickup because there is less vacuum.

In essence the arduio watches a pulsed ground injector, counts and selectively interrupts the injection by driving open a solid state relay. I am experiememting on a 1.8l. 4cyl engine and the engine still runs smoothly with every 2nd pulse interrupted for all cylinders which is essentially 50% cylinder deactivation. My initial objective is to raise the manifold pressure from about 70kPaa to say 90kPaa, rather than convert to throttles altogether. My understanding is that approx a 10-15% FE improvement is expected without touching the valves as occurred in traditional deactivation.

One challenge is how to achieve closed loop control when inactive cycles pump air into the exhaust.

I'd be curious to know if anyone else has done any research or experimentation with cycle based cylinder deactivation.

I understand the GM/ Delphi commercialising the technology this year.