Fuel system, injectors and EGR

The fuel system — from tank to combustion

The fuel system in a modern car is a high-precision system. Fuel is pumped from the tank through a filter to a high-pressure pump (on diesel and direct-injection petrol engines), and from there to the injectors which spray the fuel into the combustion chamber with extreme accuracy. The EGR valve recirculates a small portion of the exhaust back to the intake to reduce NOx emissions. We repair and maintain all parts of the system — from simple filter changes to full injector overhaul.

Diesel injectors

Modern diesel injectors are either electromagnetic or piezoelectric and operate at pressures above 2,000 bar. They must spray fuel in several micro-pulses per combustion event to ensure quiet, clean burning. When an injector fails you typically notice rough idle first, smoke from the exhaust (black = too much fuel, white = incomplete combustion, blue = oil) and reduced power. The check-engine light is usually on, and a fault code points to which cylinder has the issue. We test injectors on a flow bench or directly in the car and can often clean them if the wear isn't too far gone — otherwise they are replaced.

Petrol injectors

Petrol injectors (multi-point or direct) are simpler than diesel, but they can also clog or drip after many years. Symptoms are almost identical: rough idle, check engine, reduced power, higher fuel consumption. Direct-injection petrol engines (FSI, TSI, GDI etc.) are more prone to soot deposits on the valves because the injector sits inside the cylinder — we can clean the valves with chemical or mechanical methods. Multi-point injectors are usually cleaned by adding additive to the tank or by ultrasonic cleaning after removal.

The EGR valve — necessary but problematic

EGR (Exhaust Gas Recirculation) sends a small portion of the exhaust back to the intake. This lowers combustion temperature and therefore NOx emissions. The issue is that soot particles from the exhaust, combined with oil vapours from the intake, form a tar-like deposit that clogs the valve and intake passages over time. Symptoms of a defective EGR are check-engine light, rough idle, smoke under acceleration and power loss. We clean the EGR valve in an ultrasonic bath or replace it as needed — in many cases we combine cleaning with intake cleaning to remove soot from the whole area.

Price and clean vs replace

An original diesel injector typically costs NOK 5,000–12,000 each, and the car has 4–6 of them. Ultrasonic cleaning of an injector costs NOK 800–1,500 per unit and can save injectors that aren't too worn. EGR cleaning is typically NOK 2,500–4,500 incl. labour, while replacement is NOK 4,000–10,000. We always perform a thorough diagnosis before recommending action — replacing all injectors when only one is defective is rarely economical.

Book your repair online or call us on 41 17 32 24.