🔍 Diagnosing Diesel Injectors with Autocom – Step-by-Step Guide

🔍 Diagnosing Diesel Injectors with Autocom – Step-by-Step Guide

Diesel injectors (or fuel nozzles) are essential components in any diesel engine. When an injector fails or becomes imbalanced, it often causes rough idling, misfires, or engine vibration—especially noticeable after the engine is warm.

The Autocom diagnostic tool allows technicians to read injector correction values, detect misfiring cylinders, and monitor live engine data to pinpoint faulty injectors.

✅ What You Need:

• Autocom Diagnostic Tool (CARS version)

• OBD-II cable

• A diesel engine vehicle (e.g., Volvo V50 1.6D 2009)

• Engine warm to full operating temperature (80–95°C)

📌 Step-by-Step: Checking Injectors with

Autocom

1. Connect the Tool

• Plug the Autocom OBD-II cable into the vehicle.

• Turn the ignition ON (or start the engine).

2. Select Vehicle

• Choose the correct make, model, engine type, and year.

  

3. Enter the Engine Control Module (ECU)

• From the left menu, click on the wrench icon (🔧).

• Select the Engine Control Unit (ECU).

  

4. Open "ECU Real-Time Data" or "Live Data"

• Navigate to Live Data / Measured Values.

• Look for Injector Correction Values (may also appear as Cylinder Balancing or Fuel Quantity Compensation).

📊 Understanding Injector Correction Values

Injector correction values show how much the ECU is adjusting fuel delivery to each cylinder to maintain smooth operation.

✅ Normal Range:

-0.5 to +0.5 mm³/stroke

⚠️ Watch Range:

±0.6 to ±1.5 mm³/stroke

❌ Fault Range:

Greater than ±1.5 mm³/stroke

🧪 Example 1 – Normal Injectors:

Injector 1: +0.3
Injector 2: -0.2
Injector 3: +0.1
Injector 4: -0.4

➡️ All values are within safe limits. Injectors are working correctly.

🧪 Example 2 – Faulty Injector Detected:

Injector 1: +0.2  
Injector 2: -2.1 ❌  
Injector 3: +0.3  
Injector 4: -0.1  

➡️ Injector 2 is overcompensating, likely due to clogging or internal leakage.

🔧 What to Do If a Value is Out of Range:

• Try injector cleaner additives (e.g., Liqui Moly Diesel Purge, STP Diesel Injector Cleaner).

• If the issue remains: Remove and bench test the suspect injector.

• In some cases, injector replacement is necessary.

💡 Extra Tip: Use "Actuator Test" (if supported)

Some vehicles allow you to run each injector individually using:

• Actuator > Injector Test

• This can help confirm misfiring or non-responsive injectors.

📝 Final Thoughts

Autocom is a powerful diagnostic tool that, when used correctly, helps pinpoint diesel injector issues quickly and accurately. By reading Injector Correction Values, technicians can detect imbalances and take action before the engine suffers serious damage.