Control of auto-ignition timing for homogeneous combustion jet ignition engines

The invention relates to a method of controlling auto-ignition timing in an internal combustion engine cylinder (10) that is coupled to a prechamber (20), the method comprising: during a first stage of a compression stroke of a piston (15) in the cylinder (10), opening a microvalve (22) that couples the prechamber (20) to the cylinder (10) to bring the pressure within the prechamber (20) to a pressure level within the cylinder (10); during a selected time interval in an intermediate stage of the compression stroke, closing the microvalve (22); setting conditions in the prechamber (20) so as to cross a threshold for auto-ignition in response to a threshold increase in pressure; and inducing auto-ignition in the prechamber (20) by reopening the microvalve (22) after the pressure level within the cylinder (10) has reached a level sufficient for providing the threshold increase in pressure within a short time period of the reopening, wherein the auto-ignition in the prechamber (20) introduces hot gas jets from the prechamber (20) into the cylinder (10), resulting in auto-ignition in the cylinder (10).