HEUI injector testing, rebuild & calibration
We diagnose, rebuild and calibrate Hydraulically actuated Electronically controlled Unit Injectors for Ford Power Stroke, Caterpillar and Navistar diesel engines — bench-tested to factory spec before refitting.
Hydraulic pressure meets electronic control
A HEUI injector (Hydraulically actuated Electronically controlled Unit Injector) uses high-pressure engine oil, routed through a dedicated oil rail and high-pressure oil pump, to drive the injection event — while the injection timing and duration are controlled electronically by the ECM. This design was widely fitted to Ford Power Stroke engines (7.3L and 6.0L), and used on several Caterpillar and Navistar/International diesel platforms through the late 1990s and 2000s.
Because the injector's actuation depends on oil pressure rather than fuel pressure alone, HEUI faults often present as rough running, hard starting or excessive smoke that can be mistaken for an oil pump, high-pressure oil pump (HPOP) or ECM issue. Correct diagnosis starts with isolating whether the fault is fuel-side, oil-side or electronic before any injector is pulled.
Our technicians test each injector's spray pattern, oil consumption, return flow and electrical response on a dedicated HEUI test bench, then rebuild with new internal components and re-calibrate to the injector's coded values before it goes back in the engine.
Common Applications:
- Ford Power Stroke — 7.3L & 6.0L diesel
- Caterpillar — C7, C9, 3126, 3208
- Navistar / International — DT466, T444E
- Applications — pick-ups, medium-duty trucks, generators, marine & agricultural engines
What to look and listen for
Any of these can point to a HEUI-side fault — bring the vehicle in for bench diagnosis rather than guessing.
Hard starting or long cranking
Low oil rail pressure or a leaking injector can delay or prevent the injection event on start-up.
Rough idle or misfire
One or more cylinders not firing correctly often traces back to a single failing injector.
Excessive white or blue smoke
Unburnt fuel or oil passing through a worn injector shows up as visible exhaust smoke.
Loss of power under load
Reduced or inconsistent fuel delivery is felt most under acceleration or towing load.
Milky or diluted engine oil
Fuel leaking into the oil rail through a failed injector can contaminate the engine oil.
Fault codes for cylinder contribution
ECM-logged codes flagging an individual cylinder's fuel contribution usually point to that injector.
Fault confirmed on the bench before any parts are ordered
Every HEUI injector goes through the same repeatable sequence, so you only pay for what's actually needed.
Intake & visual inspection
Injectors are cleaned, logged and checked for external damage, oil rail seal condition and carbon build-up before any testing begins.
HEUI bench testing
Each unit is tested under simulated oil pressure and ECM signal to check spray pattern, poppet valve response and internal leakage.
Rebuild with OEM parts
Faulty internals — poppet valves, plunger assemblies, seals and o-rings — are replaced to the original manufacturer's specification.
Calibration & final test
The rebuilt injector is re-tested and calibrated for correct fuel delivery and timing before it's approved for refitting.
Free pickup & drop-off
We collect your vehicle or unit, complete the repair, and return it to you anywhere in Doha at no extra cost.