Can I keep driving with this symptom?

Briefly and gently, but injector faults rarely improve on their own and sustained running can damage the DPF, turbo or engine. Diagnose promptly.

Do I need to replace all injectors?

Not necessarily. Testing identifies the faulty unit(s); on high-mileage engines many workshops replace as a set to avoid repeat labour, but it is a judgement call.

Will a remanufactured injector fix it?

Yes — a properly remanufactured injector is rebuilt and bench-tested to OEM spec and carries a warranty, at a fraction of the new price.

Diesel Injector Problem — Black Smoke on Acceleration

Black smoke under acceleration is over-fuelling or under-airing. On the fuel side, eroded injector nozzles deliver too much, too coarsely.

Fix this issue

Most black smoke on acceleration issues in diesel engines are caused by failing fuel injectors.

✔Replace worn or leaking injectors
✔Restore performance and fuel economy
✔Prevent further engine damage

View Compatible Injectors

OEM Tested & Calibrated
12-Month Warranty
Free UK Delivery

Symptoms

Black Smoke on Acceleration

Black smoke under acceleration is over-fuelling or under-airing.

Diagnostic Tests

Visual smoke assessment

Colour, timing (cold/hot, idle/load) and density of exhaust smoke narrow the fault before any parts are touched.

Cylinder balance / contribution test

The ECU's per-cylinder correction values identify which injector is over- or under-fuelling.

Injector leak-off test

Measures return flow from each injector with graduated bottles. One injector returning well above the others is internally worn.

Common Causes

Worn injector nozzle

Eroded nozzle orifices spray a poor pattern, so fuel burns incompletely or unevenly.

Missing or wrong injector coding

Uncoded or mis-coded injectors run without their calibration trims, unbalancing the engine.

Air-path faults

Boost leaks, tired turbos and blocked air filters under-air the mixture — check alongside injectors.

Repair Solution

Run a full diagnostic scan and record all stored fault codes before clearing anything.Test before replacing: leak-off, live data and balance tests isolate the faulty injector(s).Replace confirmed faulty injectors with bench-tested remanufactured units and code them to the ECU.Always fit new copper washers and seals when an injector is removed.

Browse Remanufactured Injectors by Brand

Bosch Delphi Siemens Denso Continental