The injector fuel supply system and its errors P0172 and P0171

Administrator posted this 26 March 2019

The injector fuel supply system began to be used in cars in the 80s of the last century. Before that, the down-draft carburetor was responsible for the fuel supply to the cylinders. For today, all modern cars are equipped with injectors, according to Euro5 standards.

So, the injector is responsible for supplying the air-fuel mixture to the engine cylinder. The injector has an electronic type of nozzle control. According to the data reads of sensors (modern injectors have up to 8), the frequency and quantity of fuel-air mixture supply are monitored.

Based on the foregoing, injection of the fuel delivery system divided into: mono injection and control injection or direct injection for each injector.

Firstly, let us consider the features of the injector system. For example, it has a very complex structure, and therefore the repair and diagnosis are complicated.

Air intake and fuel mixing takes place through the throttle unit (inlet pipe assy is regulated by the gas pedal).

Fuel tank → Fuel pump → fuel drive (and drain fuel drive) → fuel pressure control→ fuel rail → injector nozzles air filter → throttle valve → intake manifold → engine cylinder - this is a simplified example of how the fuel supply in the car works, in addition to the functionality of the injector system spacer ring, gravity valve, back-pressure valve are also important.

Initially, the injection system worked on the mono injection system, it was advanced of the down-draft carburetor functionality, but under control via the ECU. However, the mono injection for cars is not applied on up-to-day models.

Distribution injection also has several variations, therefore, more common in modern cars. For example:

  • Direct fuel supply
  • Simultaneous supply of fuel
  • Pairwise-parallel fuel supply
  • Phased synchronized fuel supply

Taking into account the complexity of the system, it is necessary to pay attention to the maintenance of the system and quality fuel starting from the 95th, although today the injector system is reliable and of high quality.

Errors P0172 and P0171

Signs of error P0172-Rich mixture (lack of air)

  • First of all, it is an active signal " Check engine»
  • Claps and shots from the silencer when it comes out black or gray smoke
  • Increased fuel consumption
  • Failures in the dynamics of the car
  • Black soot on the plugs (norm brown)
  • The car won't start

In the initial stages, it will be easy and relatively inexpensive to fix the problem.

Signs of error P0171 - poor mixture (not enough fuel)

  • First of all, it is an active signal " Check engine»
  • When driving the car stalls
  • Violation of the dynamics of the car
  • Unstable "flapping" exhaust
  • The light color of soot on the plugs

The problem may lie in the malfunction of one of the injector sensors, or even a violation of the throttle valve, which only needs to be cleaned.

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