When a buyer and supplier obtain different injector test results, the immediate assumption may be that the product is defective or that one laboratory has made an error.

However, differences in test method can create different results even when both laboratories operate their equipment correctly.

Before assigning product responsibility, both sides should compare how the measurements were produced.

Acceptance Criteria Need a Defined Source

The first question should be: which specification defines acceptance?

The applicable requirement may come from:

• a controlled technical document;
• approved test procedure;
• customer specification;
• product-specific test data.

A numerical limit without its source and revision is difficult to evaluate.

Equipment Setup Can Change Results

Different laboratories may use different:

• test benches;
• adapters;
• software versions;
• test fluids;
• temperature controls;
• measurement sequences.

Any of these differences can affect the comparison.

The purpose of method review is to determine whether both results represent equivalent conditions.

Adapter Selection Is Especially Important

An adapter can affect sealing, internal volume, connection geometry, and flow path.

Using an incorrect or different adapter may change the test condition even when the injector itself is unchanged.

Adapter identification should therefore be part of the test record when relevant.

Repeat Testing Should Use Agreed Conditions

If a dispute requires confirmation, repeat testing is most useful when both parties agree in advance on:

• test method;
• equipment conditions;
• specification revision;
• units;
• acceptance limits.

Otherwise, another test may simply reproduce the original disagreement.

Product Defect and Method Mismatch Are Different Conclusions

A failed result under one method does not automatically prove a manufacturing defect.

Similarly, finding a method difference does not automatically prove the product is acceptable.

The component still needs to be evaluated under the correct agreed requirement.

FAQ

Can two laboratories obtain different results from the same injector?

Yes, especially when equipment, methods, or conditions differ.

What should be compared first during a test dispute?

Compare specifications, methods, adapters, units, temperature, equipment setup, and software versions.

Does a method mismatch prove the injector is good?

No. It means the product should be evaluated again under the correct controlled method.