After an injector repair you often hear nothing more than: “All fine, you can fit it.” No document,
no measured values, no basis for a decision. A test report is the opposite of that —
and the only way to judge a repair objectively.
What is a test report?
A test report is the written record of the measurements taken after an injector has been tested on the bench. It shows how the injector performs under defined conditions — and whether the values match the manufacturer’s specifications.
It is not a service book entry and not a warranty slip. It is a measurement document.
What is measured?
A complete report covers several operating states. The key parameters:
| Measured value | What it tells you |
|---|---|
| Injection quantity (full load) | How much fuel the injector delivers under maximum demand |
| Injection quantity (idle) | Precision at small quantities — decisive for smooth running |
| Pilot injection quantity | Small quantity before the main injection — reduces combustion noise |
| Return flow quantity | Fuel that is not injected — a high figure points to wear |
| Opening pressure / switching behaviour | At what pressure the injector opens and how precisely it switches |
| Leak tightness | Whether the injector seals when closed |
Why is “it works” not good enough?
An injector can run and still operate outside tolerance. Too much fuel delivered raises consumption and sooting. Too little means loss of power and a lean burn. A deviation of more than 2–3% between cylinders is enough to make engine running noticeably worse.
Without measurement, neither you nor the workshop knows whether the injector really is working correctly again. “It works” is not a technical statement — it is an assumption.
What is the report worth to a workshop?
For car workshops and fleet operators the test report has concrete practical value:
- Basis for a decision: can the injector be repaired, or does it have to be replaced?
- Before and after comparison: was the repair successful — in figures, not in words.
- Protection against complaints: if problems arise later, the condition at the time of repair can be evidenced.
- Documentation for the end customer: transparency builds trust — and saves arguments.
In B2B work in particular, where vehicle downtime means direct costs, a documented condition is not a nice-to-have but a standard.
What the report does not cover
A test report documents the condition of the injector on the test bench — under laboratory conditions with defined test oil and defined pressures. It does not replace diagnostics on the vehicle and gives no guarantee for the fitted condition or for fuel quality in service.
It is a starting point — not a blank cheque.
What we do at INP
Every injector repaired at INP Dieseltechnik goes through a full test bench measurement afterwards. We document the results in the test report — with actual figures for each operating point, not just a stamp.
The report goes back to the workshop or the customer together with the injector. That way everyone involved knows where they stand.
Not sure whether a repair is worthwhile?
Send us the vehicle type and injector type — we will come back to you on
the same working day with an honest assessment. Free and without obligation.
→ Open WhatsApp or +43 676 9799199
INP Dieseltechnik · Injectors & injection pumps · Vienna
