Electronic Engines — Camless Fuel, Exhaust & Start-Air Control

1. The Camless Idea — Software Replaces Steel Timing

On a conventional engine the camshaft is the timetable: fuel cams, exhaust cams and start-air distributor all cut in steel, phased once at build. Electronic engines delete that entire drive — no camshaft, no chain, no timing gears for these functions — and replace each cam event with an on-off NC (normally closed) electronic valve plus a crank-angle input. Timing becomes a number in software, changeable per revolution:

What software gains

Injection timing, rate shaping, pre-injection and exhaust open/close angles become free per load, per revolution — including slow steaming and crash-stop patterns stored in memory.

What steel loses

No cam means no cam-event interlock: a leaking valve can admit fuel with no timing signal at all — the hydraulic-lock hazard of §5.

2. Fuel Injection — Duration Meters, Servo Oil Fires

In an electronically controlled MAN ME engine, sensors and the engine control system determine when the cylinder control unit (CCU) commands the electro-hydraulic fuel-injection valve. Filtered servo oil from the Hydraulic Power Supply (HPS) operates the fuel-pressure booster; the HPS pressure is model-specific (the MAN B&W example below is about 200 bar). Electronic control can vary injection timing and pattern, while the hydraulic circuit supplies the working force. WinGD RT-flex uses a different common-rail arrangement and control terminology, so do not apply MAN's ELFI/FIVA labels to every camless engine.

Injection hardware and valve count depend on the engine model. Use its control-system drawing to trace the signal path from crank-angle/speed inputs through the ECU and CCU to the hydraulic valve and fuel-pressure booster. The injector-side tests and overhaul rhythm live in Fuel Injectors — Atomisation, 7 Tests & Overhaul.

3. Exhaust Valve — Hydraulic Muscle, Free Timing

On the MAN ME system shown here, filtered servo oil from the HPS operates the exhaust-valve actuator through an electronically controlled valve (ELVA). Pressure, actuator details and control strategy vary by engine series. Electronic control allows the specified opening event to be commanded by the control system; it does not remove the need to follow the maker's timing and maintenance procedures:

• Servo-oil activation pressure: 300 bar
• Central exhaust valve per cover: 1 / cyl
• Fuel valves per cover by bore: 2–3

4. Controllers — One Per Cylinder, One Spare for All

Electronic engine control is layered. Engine-level controllers coordinate with cylinder control units (CCUs), but which functions each CCU owns and how redundancy works depend on the engine series. A failure may disable one cylinder or initiate another protective response; the maker's control-system manual defines the actual alarm, fallback and restart procedure:

Do not assume that a failed CCU is always replaced by an automatic standby controller while the cylinder continues firing. One MAN B&W description says the affected cylinder is put out of operation if its CCU fails; the actual alarm, cut-out and redundancy logic must be read from the installed ECS manual.

5. ME vs RT-flex — and the Uncontrolled-Fuel Hazard

The hazard both share: with no cam event gating the fuel, a leaking injection valve or HP line can feed fuel into a cylinder uncontrolled — and liquid does not compress, so the unit heads for hydraulic lock. The defences are layered: fuel-leakage collection with alarms, crankshaft-deflection monitoring that catches the overloaded throw, double-walled HP pipes that contain bursts, and scavenge-space design that keeps stray fuel away from hot steel:

Reversing and starting logic for these engines extends the cam-engine story in Starting & Reversing; exhaust-valve hardware detail sits with Four-Stroke Aux Design and timing practice in Valve Gear & Fuel Injection.