Ignition systems — accuracy and control Which ignition system offers the most accurate and consistent spark timing in a modern spark-ignition engine?

Introduction / Context:
Accurate ignition timing maximizes torque, reduces emissions, and prevents knock. Different systems vary in precision, stability, and adaptability to engine conditions.

Given Data / Assumptions:

• Comparison among magneto, breaker-point, and ECU-controlled systems.
• Engine speed and load vary continuously; sensors provide feedback.

Concept / Approach:
ECU-controlled ignition uses sensors (crank/cam position, MAP/MAF, knock, temperature) and mapped algorithms to schedule spark events with high angular accuracy. Solid-state drivers and coil-per-plug minimize energy loss and dwell variability over the rev range.

Step-by-Step Solution:
Determine requirement: precise, adaptive timing.ECU reads position and load → computes advance.Igniter triggers coils accurately even at high rpm.Therefore, ECU ignition is most accurate.

Verification / Alternative check:
Scope traces of coil primary show tight timing scatter with ECU systems; mechanical points show more drift due to wear and bounce.

Why Other Options Are Wrong:
Magnetos are robust but timing is mechanically fixed or limited.

Breaker-point systems suffer from dwell and cam-follower wear.

Hybrid without ECU lacks closed-loop adaptability.

Manual advance cannot react continuously to transient conditions.

Common Pitfalls:
Faulty sensors (e.g., CKP, CMP) or poor grounds can still degrade timing accuracy; ensure proper shielding and calibration.

Final Answer:
electronic control unit (ECU)–controlled ignition