Cylinder Corrections Remain Abnormal After Injector Replacement and Coding in Port Tractors, Prompting Mozambican Repairers to Reset Learned Values, Verify Cylinder Mapping and Complete Load Relearning

Injector Coding May Not Complete the Repair Process

Port tractors operate through repeated acceleration, low-speed manoeuvring and load changes. After a diesel injector is replaced, technicians may enter the new calibration code correctly but continue to see abnormal cylinder correction values.

Mozambican repairers examining this issue are reviewing ECU learned values, cylinder mapping and post-repair relearning procedures.

Coding identifies the installed injector to the control system. Learned values represent how the ECU has adapted to previous engine behaviour. These are related functions, but they are not always the same process.

Why Old Adaptations Can Remain

Before replacement, the ECU may have adjusted control to compensate for:

• Injector delivery variation;
• Low compression;
• Airflow differences;
• Fuel-pressure instability;
• Wiring resistance;
• Engine wear;
• Previous incorrect coding.

After the injector is changed, some control systems require an adaptation reset or relearn before the data stabilises around the new component.

Not every engine uses the same reset procedure, so manufacturer-specific diagnostic information is required.

Verify Cylinder Mapping First

Physical Cylinder Position

The workshop should confirm the engine’s official cylinder numbering. General assumptions about the front or flywheel end can create mapping errors.

Installed Injector Code

Each calibration code should be compared with the physical injector installed in that cylinder.

Photographs and removal tags help prevent code transposition during multi-injector service.

Diagnostic Display

The codes stored in the ECU should be read back after programming. Successful data entry does not guarantee that the correct code was entered into the correct location.

Resetting Learned Values

Where the engine service procedure requires it, the diagnostic tool can clear relevant injector or cylinder adaptations.

A complete ECU reset should not be performed casually because unrelated learned information may also be affected.

The correct function may be described as injector learning, cylinder balancing, pilot correction, quantity adjustment or another manufacturer-specific term.

Completing a Relearning Cycle

Warm-Up

The engine may need to reach normal operating temperature before learning becomes active.

Stable Operating Points

The procedure may require idle, fixed speed or staged load operation.

Road or Work-Cycle Verification

For port tractors, final evaluation should include representative manoeuvring and load response rather than only workshop idle.

Technicians should monitor correction values, rail pressure, engine speed, exhaust condition and fault codes.

Check Non-Learning Causes

Persistent correction values can still result from compression, valve condition, wiring, air supply or incorrect injector delivery.

A relearn procedure should not be used to hide a mechanical or hydraulic fault.

Replacement Selection Guidance

The injector must match the complete OE number, engine serial range, power configuration, emissions level and code format.

A code accepted by the diagnostic tool does not prove the injector is hydraulically correct for the engine.

Industry Interpretation

Mozambican port-equipment workshops can improve post-replacement verification by separating three tasks: correct injector selection, correct cylinder coding and correct ECU adaptation.

When correction values remain abnormal, cylinder mapping and learning status should be checked before the new injector is rejected.

The final decision should combine relearning results with engine data and model-specific injector testing.