1. What is Injector Duty Cycle?

The Injector Duty Cycle (IDC) represents the percentage of time the fuel injector is open during an engine cycle. It's a critical parameter for engine tuning and fuel system design.

2. How Does the Calculator Work?

The calculator uses the standard IDC equation:

Where:

• \( PW_{ms} \) — Injector pulse width in milliseconds
• \( RPM \) — Engine speed in revolutions per minute
• 1200 — Conversion factor for 4-stroke engines (2 revs per cycle × 600 ms per second)

Explanation: The equation calculates what percentage of the total available time the injector is open at a given RPM.

3. Importance of IDC Calculation

Details: Monitoring IDC is essential for preventing injector overuse (typically kept below 80-90% for safety), tuning fuel delivery, and diagnosing fuel system issues.

4. Using the Calculator

Tips: Enter pulse width in milliseconds and engine RPM. Both values must be positive numbers for calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is a safe IDC limit?
A: Most tuners recommend keeping IDC below 80-90% for reliable operation and to allow headroom for transient conditions.

Q2: How does IDC change with RPM?
A: At constant pulse width, IDC increases linearly with RPM. Higher RPM means less time available per cycle for injection.

Q3: What if my IDC exceeds 100%?
A: Values over 100% indicate the injector cannot deliver the required fuel at that RPM, suggesting the need for larger injectors.

Q4: Does this apply to all engine types?
A: This formula is for 4-stroke engines. For 2-stroke engines, the denominator would be 600 instead of 1200.

Q5: How accurate is this calculation?
A: It provides a good estimate, but actual IDC may vary slightly due to injector latency and other factors.