5 signs your petrol injectors need cleaning
Rough idle, misfires, poor MPG? Here are the five clearest signs your petrol fuel injectors are clogged — and what ultrasonic cleaning and flow testing can do about it.
Fuel injectors spray a precise, atomised mist of fuel into your engine. Over time, heat bakes fuel deposits into lacquer and carbon inside the injector, disrupting that spray. The result is an engine that runs rough and drinks fuel. Here are the five clearest signs it’s time to have your injectors cleaned and flow-tested.
1. Rough or lumpy idle
If the engine shakes or hunts at idle, one or more injectors may be delivering an uneven spray. Because idle uses very little fuel, even a small restriction shows up clearly.
2. Misfires and hesitation
A blocked injector can lean out a cylinder, causing a misfire under load or a flat spot when you accelerate. You may feel a stumble or see a misfire code.
3. Worse fuel economy
When the spray pattern degrades, fuel isn’t burned efficiently and your MPG drops. Many owners notice a real difference at the pump after a clean.
4. Failed emissions / high hydrocarbons
Poor atomisation means unburnt fuel, which pushes up emissions. Injector cleaning is often the cheapest route to passing a test.
5. Hard starting after standing
Cars left standing — classics, project cars, seasonal vehicles — often suffer as fuel dries to varnish inside the injectors.
What cleaning actually does
Chemical fuel additives rarely touch baked-on deposits. Ultrasonic injector cleaning drives cavitation through the injector’s internal passages to lift lacquer and carbon, and every injector is flow-, leak- and spray-tested before and after — so you get measured proof of the improvement, with new seals and o-rings fitted as standard.
Not sure if it’s your injectors? Request a free quote and tell us the symptoms.