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A faulty injector cannot be identified by ear: it is found by measuring the return flow, the delivery and the corrections per cylinder read from the ECU. Replacing them all “to be safe” is almost always useless and expensive.

Typical symptoms

• Rough engine at idle, more pronounced knocking
• Hard starting when hot or cold
• Black or white smoke
• Rising consumption and loss of power
• Fault codes on injection corrections or rail pressure

The tests that matter

• Return-flow test: an injector returning too much fuel is out of tolerance
• Delivery test on the bench: quantity injected in the different phases
• Corrections per cylinder in diagnosis: they show which cylinder receives too much or too little
• Checking rail pressure during cranking and under load

After replacement

New or reconditioned injectors must be coded into the ECU with their respective calibration codes: without coding, the engine stays rough.

How MasterTuning helps

We check the component with real measurements, not by elimination: flow rates, pressures, corrections and signals read directly from the ECU. We repair, replace and recalibrate the software when needed. Centres throughout Italy.

Read more: vehicle database · what is ECU remapping · original files archive

Want an accurate diagnosis? Contact MasterTuning and book at your nearest centre.

Frequently asked questions

Do additives really clean injectors?

They can help with light deposits, but they do not recover a mechanically worn injector or one with excessive return flow.

Do new injectors need coding?

Yes: each injector has a calibration code that must be written into the ECU, otherwise the engine runs rough.

Can only the faulty injectors be replaced?

Yes, if the others are within tolerance on the return-flow and delivery tests: there is no need to change them all.