Customer Background

An Italian diesel workshop investigated a persistent rough-running complaint affecting one cylinder.

Injector correction data pointed toward an imbalance, but the workshop wanted more evidence before removing the injector.

Using Crankshaft Speed Information

Modern engine control systems can detect small differences in crankshaft acceleration as each cylinder contributes torque.

A cylinder producing less effective combustion may create a different speed pattern.

However, the reason can be fuel-related or mechanical.

Comparing Multiple Data Sources

The workshop compared cylinder correction information with cylinder contribution behavior and available crankshaft-speed data.

The diagnostic review then considered:

• injector operation
• cylinder compression
• valve condition
• other mechanical influences

Why Data Correlation Helped

If both fuel correction and crankshaft contribution pointed toward the same cylinder, the workshop had a clearer area for further testing.

It still did not prove that the injector was defective.

Mechanical inspection remained necessary before the final repair decision.

Case Conclusion

This Italy case demonstrates how several data sources can narrow a diesel roughness investigation without turning one ECU value into an automatic injector verdict.